DnaA

Last updated
Chromosomal replication initiator protein dnaA
Identifiers
Organism Escherichia coli
(str. K-12 substr. MG1655)
SymbolDnaA
Entrez 948217
RefSeq (Prot) NP_418157.1
UniProt P03004
Other data
Chromosome genome: 3.88 - 3.88 Mb
Search for
Structures Swiss-model
Domains InterPro
Bac_DnaA_C
PDB 1j1v EBI.jpg
crystal structure of dnaa domainiv complexed with dnaabox dna
Identifiers
SymbolBac_DnaA_C
Pfam PF08299
Pfam clan CL0123
InterPro IPR013159
SCOP2 1j1v / SCOPe / SUPFAM
Available protein structures:
Pfam   structures / ECOD  
PDB RCSB PDB; PDBe; PDBj
PDBsum structure summary

DnaA is a protein that activates initiation of DNA replication in bacteria. [1] Based on the Replicon Model, a positively active initiator molecule contacts with a particular spot on a circular chromosome called the replicator to start DNA replication. [2] It is a replication initiation factor which promotes the unwinding of DNA at oriC. [1] The DnaA proteins found in all bacteria engage with the DnaA boxes to start chromosomal replication. The onset of the initiation phase of DNA replication is determined by the concentration of DnaA. [1] DnaA accumulates during growth and then triggers the initiation of replication. [1] Replication begins with active DnaA binding to 9-mer (9-bp) repeats upstream of oriC. [1] Binding of DnaA leads to strand separation at the 13-mer repeats. [1] This binding causes the DNA to loop in preparation for melting open by the helicase DnaB. [1]

Contents

Bac_DnaA
PDB 2hcb EBI.jpg
structure of amppcp-bound dnaa from aquifex aeolicus
Identifiers
SymbolBac_DnaA
Pfam PF00308
Pfam clan CL0023
InterPro IPR013317
PROSITE PDOC00771
SCOP2 1j1v / SCOPe / SUPFAM
Available protein structures:
Pfam   structures / ECOD  
PDB RCSB PDB; PDBe; PDBj
PDBsum structure summary

Function

DnaA consists mainly in two different forms, the active ATP-form and the inactive ADP. [1] [3] The level of active DnaA within a cell is low immediately after a cell has divided. [1] Although the active form of DnaA requires ATP, the formation of the oriC/DnaA complex and subsequent DNA unwinding does not require ATP hydrolysis. [4]

The oriC site in E. coli has three A T rich 13 base pair regions (DUEs) followed by four 9 bp regions with the sequence TTAT(C or A)CA(C or A)A. [5] DnaA molecules bind to the 9 bp regions, which wrap around the proteins causing the DNA at the AT-rich region to unwind. [6] There are currently 11 DnaA binding sites identified within oriC, to which DnaA binds with differential affinity. [6] When DNA replication is about to commence, DnaA occupies all of the high and low affinity binding sites. The denatured AT-rich region allows for the recruitment of DnaB (helicase), which complexes with DnaC (helicase loader). DnaC helps the helicase to bind to and to properly accommodate the ssDNA at the 13 bp region; this is accomplished by ATP hydrolysis, after which DnaC is released. Single-strand binding proteins (SSBs) stabilize the single DNA strands in order to maintain the replication bubble. DnaB is a 5'→3' helicase, so it travels on the lagging strand. It associates with DnaG (a primase) to form the only primer for the leading strand and to add RNA primers on the lagging strand. The interaction between DnaG and DnaB is necessary to control the longitude of Okazaki fragments on the lagging strand. DNA polymerase III is then able to start DNA replication.

DnaA is made up of four domains: the first is the N-terminal that associates with regulatory proteins, the second is a helical linker region, the third domain is a AAA+ region that binds to ATP, and the fourth domain is the C-terminal DNA binding region. [7] DnaA contains two conserved regions: the first is located in the central part of the protein and corresponds to the ATP-binding domain, the second is located in the C-terminal half and is involved in DNA-binding. [8]

DnaA mutants

The first strains to have the dnaA gene mutated were the temperature-sensitive K-12 strains CRT46 and CRT83, with the corresponding strain numbers beingdnaA46 and dnaA83. In contrary to dnaA mutants, the PC2 strain has a mutation in the dnaC gene, which codes for the loading factor for the DNA helicase dnaB. [9]

Synthesis

DnaA has the ability to bind its own promoter. When DnaA binds to its own promoter it blocks RNA polymerase from binding the promoter and inhibits initiation of transcription. In this way, DnaA is able to regulate its own expression. [3] [10] This process is called autoregulation. [11]

Regulation

Each cell division cycle triggers a new round of chromosome replication with the accumulation of DnaA, the initiator protein, on the OriC region of DNA. [12] It is crucial to regulate DnaA-ATP monomer interactions with oriC during helicase loading and unwinding of origin DNA for precise timing. DnaA recognition sites in Escherichia coli are arranged in OriC to facilitate staged pre-replication complex assembling, with DnaA interacting with low affinity sites as it oligomerizes to fill the gaps between high affinity sites as it oligomerizes. There may be numerous gap-filling strategies to link OriC functions to bacterial lifestyles in nature, which may account for the wide variability of OriC DnaA recognition site patterns. [4] The two forms of DnaA, the active ATP- and ADP-form are regulated. The ATP-form is converted to the ADP-form through either Regulatory inactivation of DnaA (RIDA), [13] which in turn consists of the Hda protein and the β sliding clamp (DnaN) [14] and datA-dependent DnaA-ATP hydrolysis. [15] The ADP-form is converted to the ATP-form by DnaA-reactivating sequences 1 and 2 (DARS1 and DARS2). [16]

Regulation of DnaA binding to DNA at OriC

Since DNA replication must occur irreversibly and only once per cycle, the binding behavior of DnaA complexes to OriC is a highly regulated, and therefore dependent on many other cellular mechanisms. [17] [18] While all OriC sites are bound at replication initiation, there are three high-affinity binding sites–R1, R2, and R4–that are typically occupied by DnaA for the majority of the cell cycle, thus making their binding somewhat less dependent of other events happening within the cell at a given point in time. [4] [19]  By contrast, the lower affinity sites are typically only bound to DnaA complexes right before replication begins. [6] There are currently eight identified sites with lower DnaA/OriC binding affinity: R5 (or R5M), I1, I2, I3 and R3, tau2, C1, C2 and C3. [20] Between the R1 and R2 high affinity sites exist the R5M, tau2, I1, and I2 low affinity sites, and C3, C2, 13, and C1 exist between the R2 and R4 sites. [6] The I sites, tau2, C2, and C3 sites preferentially bind with and are more efficient at binding to DnaA in its ATP-bound active form (DnaA-ATP) prior to DNA strand separation, whereas the R1-R5 sites and C1 site have not demonstrated a preference for binding with DnaA-ATP over DnaA-ADP. [21] OriC binding with active DnaA-ATP complexes at the lower affinity I sites, as well as the tau2, C2, and C3, sites is required for the strand separation process to initiate in a time regulated manner, meaning DnaA-ATP cannot be substituted with inactive DnaA-ADP complexes to initiate replication properly and with sufficient regulation. [6] Recent studies suggest that while OriC sites bound entirely to DnaA-ADP complexes are capable of preparing the cell for DNA replication, they struggle to maintain the healthy and consistent replication frequency regulation cells continuing OriC sites bound to DnaA-ATP complexes achieve, perhaps explaining why some sites bind preferentially to the active DnaA conformation over the inactive conformation. [6] [21] Two other proteins, an integration host factor (IHF) protein and a DnaA initiator associating (DiaA) protein, help facilitate the binding of DnaA-ATP complexes to the OriC sites and set the stage for replication initiation to occur. [17] [22] [23]

IHF plays a key functional role positively regulating the binding of DnaA complexes to the lower affinity OriC sites as the cell prepares for replication, essentially evening the playing field between the high and low affinity OriC sites in terms of their ability to bind with DnaA complexes. [24] Cooperative binding is thought to be a mechanism in which the high-affinity sites supply the lower-affinity sites within their vicinity with DnaA-ATP complexes in the moments leading up to replication initiation. [6] While DnaA can saturate all OriC binding sites in systems lacking IHF, a much higher concentration of DnaA is needed in the cellular environment for this to be achieved. [24] However, in these situations, cells also experience a loss of synchronization in their replication initiation timing, indicating how important IHF is for maintaining consistent regulation of this process in cells and preventing a lag in the initiation of replication. [6] [24] When IHF is present in a cellular system, IHF enhances DnaA binding to low affinity OriC sites without any need for increasing the baseline concentration of DnaA present, further highlighting its importance in maintaining replication initiation timing. [6] [24]

Conformationally, IHF assists in promoting the process of DnaA-ATP complexes binding to the low affinity OriC binding sites at the right time by binding to a different site on OriC ahead of replication initiation, causing DNA it to bend in such a way that facilitates efficient binding with DnaA-ATP complexes. [19] [18] Prior to IHF binding to OriC, a different protein, factor for inversion stimulation (FIS) protein, is bound to DNA for the majority of the cell cycle (with the exception of the events leading up to replication initiation), inhibiting the binding of IHF to DNA. [19] [18] [25] Consequently, the binding of DnaA complexes to the lower affinity OriC sites is also inhibited, thus, preventing the chromosomal replication process from starting prematurely and thereby demonstrating how FIS positively regulates the maintenance of a consistent cell cycle progression via inhibition. [6] [19] [18] [25] As FIS binding to OriC weakens, IHF begins to bind to OriC, therefore increasing the low affinity sites’ ability to bind to DnaA-ATP complexes, concurrent with IHF binding. [18] The switch from FIS binding to IHF binding to DNA is hypothesized to be brought about by the generation of more DnaA-ATP complexes, promoted by the existence of the high affinity sites bound to DnaA while FIS is concurrently bound to DNA, which are then recruited to the high affinity region and build up, exerting a conformational stress on bound FIS (especially by accumulation at the R2 site, as it is closest to the FIS binding site), thereby deteriorating its binding ability with DNA. [6] [18] As a result, IHF can take advantage of the weakened state of FIS binding so that it can then bind to its own respective OriC site, causing DNA to bend and essentially align the accumulated DnaA-ATP complexes better with the low affinity binding sites, thus aiding in the facilitation of their binding with DnaA-ATP. [18] In the absence of the switch-like behavior that occurs with the transition from FIS to IHF binding to DNA, cells are unable to maintain a control over the sequence of events that ensure replication initiation happens both irreversibly and only once per cell cycle. [6]

DiaA positively regulates the replication initiation timeline by facilitating the binding of DnaA-ATP complexes on OriC sites. [22] [26] DiaA binds to DnaA in its tetrameric form (consisting of four DiaA protomers (individual proteins) bound to one another), specifically to the first domain of DnaA–in the same region where another protein, replicative DNA helicase (DnaB), is presumed to bind with DnaA. [17] [26] Due to its tetrameric structure, DiaA has the ability to bind to multiple DnaA-ATP complexes at a time, as each protamer within the homotetramer consists of an DnaA-ATP binding site. [26] This beneficial characteristic of DiaA tetramers can aid in promoting the cooperative binding behavior of transferring DnaA-ATP molecules to different sites on the OriC region of DNA as the cell prepares to undergo chromosomal replication. [26] DiaA also negatively regulates the chromosomal replication process by inhibiting the binding of the DnaB protein, whose presence and function is required for chromosomal replication, from binding to DnaA-ATP complexes assembled on OriC, therefore helping to preserve the inflexible regulation sequence of events needed for a controlled replication process and prevents asynchronous initiation within the overall cycle cycle. [17] [26] Thus, taken together, IHF and DiaA, along with the proteins they interact with in their respective binding mechanisms, are very both important for helping DnaA-ATP complexes bind to all the identified binding sites on OriC, including the low affinity sites, within a timely manner that ensures replication initiation occurs irreversibly and only a single time during the cell cycle. [23]

Once replication initiation has occurred and DNA has undergone strand separation successfully, a different process commences to make sure DnaA-ATP cannot bind directly to DNA again with a protein that negatively regulates replication initiation–the locus of datA–SeqA. [17] [19] When DNA unwinds post-initiation, new replication forks are generated, a process that subsequently leads to the unbinding of DnaA complexes from the OriC sites. [6] [27] DNA’s GATC sites within OriC and at the region where the dnaA promoter exists become hemimethylated, and therefore experience a reduced ability to function and express the same way as they would while methylated. [6] [27] SeqA is able to physically prevent replication from starting up again prematurely by binding to the hemimethylated GATA sites on OriC–many of which somewhat overlap with a couple of the low affinity binding DnaA binding sites, as well as IHF’s binding site on OriC–essentially shielding IHF and DnaA from binding to OriC. [6] [27] However, the high affinity OriC DnaA complex binding sites are not blocked by SeqA binding to DNA, thus explaining how DnaA stays bound to the three high affinity sites throughout the majority of the cycle cycle duration. [6] When GATC sites are bound to SeqA while hemimethylated, they are limited in their ability to synthesize new DnaA proteins as well, thus causing DnaA concentration within the cell to decline post initiation. [6] Thus, with these sites blocked by SeqA, DnaA-ATP binding to some of the lower affinity sites is not possible for a combination of reasons. [6] [17] In studies performed with strains lacking the ability to produce SeqA, cells were unable to synchronously initiate replication once per cycle, mirroring the effects of what happens when cells lack IHF. [19] [27] Since the binding of the low affinity sites on OriC are basically the key event that kick start replication initiation and DNA’s unraveling, SeqA’s blocking of DnaA-ATP complex binding during the majority of the cell cycle is vital for keep cells healthy by maintaining a consistent cycle. [27]

DnaA protein structure

There are four disciplines within the DnaA protein. An initial comparison of Escherichia coli and Bacillus subtilis proteins led to the discovery of a sphere structure, which revealed a relatively conserved N-terminus and a largely conserved large C-terminus separated by a region that was mostly variable. [28] As an example, the Enterobacterial proteins have nearly identical N- and C-terminal sequences, however they are characterized by numerous amino acid adjustments, elisions, and insertions in the variable regions. [29] There is an AAA+ family ATPase motif and an independent DNA binding sphere in the C-terminal region. It was determined by NMR that Escherichia coli sphere IV had a crystal-clear structure when complexed with a DnaA- box. As a result, it was confirmed that the DNA list is intermediated by a combination of a helix-turn-helix motif and an introductory circle. When bound to ATP, but not to ADP, DnaA forms a super-helical structure with four monomers per turn. The structure of sphere I has been determined from three additional bacterial species and Escherichia coli by NMR. [30]

Autoregulation of DnaA protein synthesis

DnaA protein structure PDB 1pji EBI.jpg
DnaA protein structure

The research on dnaA(Ts) mutants provided the first proof that the dnaA gene is autoregulated. DnaA protein is still produced at non-permissive temperatures where it is inactive, but in some mutants it can be made active again by returning to a temperature that is conducive to development. [29] This reversible initiation capacity—which was larger than anticipated given the mass gain of the culture—could be seen in the absence of protein synthesis at the permissive temperature and suggested that the DnaA protein synthesis was derepressed at the high growth temperature. These results prompted a thorough investigation of the dnaA46 mutant under permissive, intermediate, and non-permissive development conditions. [31] The study's findings revealed that as growth temperature increased, the DnaA46 protein's activity decreased, leading to progressively decreasing DNA and origin concentrations at intermediate temperatures. An increase in initiation capacity was seen concurrently with a decrease in DnaA protein activity. Hansen and Rasmussen (1977) argued that the DnaA protein had a positive effect in replication initiation aing transcripts entering the dnaA gene were found as a result of sequencing the dnaA promoter region and the dnaA gene. [31] The DnaA promoter region has nine GATC sites within 225 base pairs, and a sequence that is similar to nd a negative role in its own synthesis based on these observations. Two promoters providrepetitions (DnaA-boxes) in the oriC region was found between the two promoters. According to several studies, the DnaA protein negatively regulates both promoters. In these research, it was discovered that the dnaA transcription was upregulated by 4- to 5-fold at non-permissive temperatures in dnaATs mutants and repressed by the same amount when DnaA protein was overproduced. The autoregulation of the dnaA gene requires the DnaA-box. [32] The sequence of the dnaA2p promoter region has some intriguing characteristics that can be seen more clearly. This promoter contains two GATC sites, one in the 10 sequence and the other in the 35 sequence, and both in vivo and in vitro, methylation increases transcription from this promoter by a factor of two. In addition, DnaA protein binds to regions upstream of the dnaA2p promoter with a high affinity. [11]

See also

Related Research Articles

<span class="mw-page-title-main">DNA replication</span> Biological process

In molecular biology, DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule. DNA replication occurs in all living organisms acting as the most essential part of biological inheritance. This is essential for cell division during growth and repair of damaged tissues, while it also ensures that each of the new cells receives its own copy of the DNA. The cell possesses the distinctive property of division, which makes replication of DNA essential.

<span class="mw-page-title-main">Lambda phage</span> Bacteriophage that infects Escherichia coli

Enterobacteria phage λ is a bacterial virus, or bacteriophage, that infects the bacterial species Escherichia coli. It was discovered by Esther Lederberg in 1950. The wild type of this virus has a temperate life cycle that allows it to either reside within the genome of its host through lysogeny or enter into a lytic phase, during which it kills and lyses the cell to produce offspring. Lambda strains, mutated at specific sites, are unable to lysogenize cells; instead, they grow and enter the lytic cycle after superinfecting an already lysogenized cell.

dnaB helicase

DnaB helicase is an enzyme in bacteria which opens the replication fork during DNA replication. Although the mechanism by which DnaB both couples ATP hydrolysis to translocation along DNA and denatures the duplex is unknown, a change in the quaternary structure of the protein involving dimerisation of the N-terminal domain has been observed and may occur during the enzymatic cycle. Initially when DnaB binds to dnaA, it is associated with dnaC, a negative regulator. After DnaC dissociates, DnaB binds dnaG.

<span class="mw-page-title-main">Origin of replication</span> Sequence in a genome

The origin of replication is a particular sequence in a genome at which replication is initiated. Propagation of the genetic material between generations requires timely and accurate duplication of DNA by semiconservative replication prior to cell division to ensure each daughter cell receives the full complement of chromosomes. This can either involve the replication of DNA in living organisms such as prokaryotes and eukaryotes, or that of DNA or RNA in viruses, such as double-stranded RNA viruses. Synthesis of daughter strands starts at discrete sites, termed replication origins, and proceeds in a bidirectional manner until all genomic DNA is replicated. Despite the fundamental nature of these events, organisms have evolved surprisingly divergent strategies that control replication onset. Although the specific replication origin organization structure and recognition varies from species to species, some common characteristics are shared.

<span class="mw-page-title-main">Pre-replication complex</span>

A pre-replication complex (pre-RC) is a protein complex that forms at the origin of replication during the initiation step of DNA replication. Formation of the pre-RC is required for DNA replication to occur. Complete and faithful replication of the genome ensures that each daughter cell will carry the same genetic information as the parent cell. Accordingly, formation of the pre-RC is a very important part of the cell cycle.

<span class="mw-page-title-main">RuvABC</span> Protein complex

RuvABC is a complex of three proteins that mediate branch migration and resolve the Holliday junction created during homologous recombination in bacteria. As such, RuvABC is critical to bacterial DNA repair.

<span class="mw-page-title-main">Nucleoid</span> Region within a prokaryotic cell containing genetic material

The nucleoid is an irregularly shaped region within the prokaryotic cell that contains all or most of the genetic material. The chromosome of a typical prokaryote is circular, and its length is very large compared to the cell dimensions, so it needs to be compacted in order to fit. In contrast to the nucleus of a eukaryotic cell, it is not surrounded by a nuclear membrane. Instead, the nucleoid forms by condensation and functional arrangement with the help of chromosomal architectural proteins and RNA molecules as well as DNA supercoiling. The length of a genome widely varies and a cell may contain multiple copies of it.

DNA gyrase, or simply gyrase, is an enzyme within the class of topoisomerase and is a subclass of Type II topoisomerases that reduces topological strain in an ATP dependent manner while double-stranded DNA is being unwound by elongating RNA-polymerase or by helicase in front of the progressing replication fork. It is the only known enzyme to actively contribute negative supercoiling to DNA, while it also is capable of relaxing positive supercoils. It does so by looping the template to form a crossing, then cutting one of the double helices and passing the other through it before releasing the break, changing the linking number by two in each enzymatic step. This process occurs in bacteria, whose single circular DNA is cut by DNA gyrase and the two ends are then twisted around each other to form supercoils. Gyrase is also found in eukaryotic plastids: it has been found in the apicoplast of the malarial parasite Plasmodium falciparum and in chloroplasts of several plants. Bacterial DNA gyrase is the target of many antibiotics, including nalidixic acid, novobiocin, albicidin, and ciprofloxacin.

<span class="mw-page-title-main">T7 phage</span> Species of virus

Bacteriophage T7 is a bacteriophage, a virus that infects bacteria. It infects most strains of Escherichia coli and relies on these hosts to propagate. Bacteriophage T7 has a lytic life cycle, meaning that it destroys the cell it infects. It also possesses several properties that make it an ideal phage for experimentation: its purification and concentration have produced consistent values in chemical analyses; it can be rendered noninfectious by exposure to UV light; and it can be used in phage display to clone RNA binding proteins.

<span class="mw-page-title-main">DNA unwinding element</span> Initiation site for the opening of the DNA double helix

A DNA unwinding element is the initiation site for the opening of the double helix structure of the DNA at the origin of replication for DNA synthesis. It is A-T rich and denatures easily due to its low helical stability, which allows the single-strand region to be recognized by origin recognition complex.

In molecular biology, origin recognition complex (ORC) is a multi-subunit DNA binding complex that binds in all eukaryotes and archaea in an ATP-dependent manner to origins of replication. The subunits of this complex are encoded by the ORC1, ORC2, ORC3, ORC4, ORC5 and ORC6 genes. ORC is a central component for eukaryotic DNA replication, and remains bound to chromatin at replication origins throughout the cell cycle.

<span class="mw-page-title-main">Prokaryotic DNA replication</span> DNA Replication in prokaryotes

Prokaryotic DNA Replication is the process by which a prokaryote duplicates its DNA into another copy that is passed on to daughter cells. Although it is often studied in the model organism E. coli, other bacteria show many similarities. Replication is bi-directional and originates at a single origin of replication (OriC). It consists of three steps: Initiation, elongation, and termination.

<span class="mw-page-title-main">Eukaryotic DNA replication</span> DNA replication in eukaryotic organisms

Eukaryotic DNA replication is a conserved mechanism that restricts DNA replication to once per cell cycle. Eukaryotic DNA replication of chromosomal DNA is central for the duplication of a cell and is necessary for the maintenance of the eukaryotic genome.

fis E. coli gene

fis is an E. coli gene encoding the Fis protein. The regulation of this gene is more complex than most other genes in the E. coli genome, as Fis is an important protein which regulates expression of other genes. It is supposed that fis is regulated by H-NS, IHF and CRP. It also regulates its own expression (autoregulation). Fis is one of the most abundant DNA binding proteins in Escherichia coli under nutrient-rich growth conditions.

<span class="mw-page-title-main">Replication terminator Tus family</span>

Tus, also known as terminus utilization substance, is a protein that binds to terminator sequences and acts as a counter-helicase when it comes in contact with an advancing helicase. The bound Tus protein effectively halts DNA polymerase movement. Tus helps end DNA replication in prokaryotes.

<span class="mw-page-title-main">Circular chromosome</span> Type of chromosome

A circular chromosome is a chromosome in bacteria, archaea, mitochondria, and chloroplasts, in the form of a molecule of circular DNA, unlike the linear chromosome of most eukaryotes.

<span class="mw-page-title-main">SeqA protein</span>

In molecular biology the SeqA protein is found in bacteria and archaea. The function of this protein is highly important in DNA replication. The protein negatively regulates the initiation of DNA replication at the origin of replication, in Escherichia coli, OriC. Additionally the protein plays a further role in sequestration. The importance of this protein is vital, without its help in DNA replication, cell division and other crucial processes could not occur. This protein domain is thought to be part of a much larger protein complex which includes other proteins such as SeqB.

<span class="mw-page-title-main">Bacterial DNA binding protein</span>

In molecular biology, bacterial DNA binding proteins are a family of small, usually basic proteins of about 90 residues that bind DNA and are known as histone-like proteins. Since bacterial binding proteins have a diversity of functions, it has been difficult to develop a common function for all of them. They are commonly referred to as histone-like and have many similar traits with the eukaryotic histone proteins. Eukaryotic histones package DNA to help it to fit in the nucleus, and they are known to be the most conserved proteins in nature. Examples include the HU protein in Escherichia coli, a dimer of closely related alpha and beta chains and in other bacteria can be a dimer of identical chains. HU-type proteins have been found in a variety of bacteria and archaea, and are also encoded in the chloroplast genome of some algae. The integration host factor (IHF), a dimer of closely related chains which is suggested to function in genetic recombination as well as in translational and transcriptional control is found in Enterobacteria and viral proteins including the African swine fever virus protein A104R.

The gua operon is responsible for regulating the synthesis of guanosine mono phosphate (GMP), a purine nucleotide, from inosine monophosphate. It consists of two structural genes guaB (encodes for IMP dehydrogenase or and guaA apart from the promoter and operator region.

<span class="mw-page-title-main">GrpE</span> InterPro Family

GrpE is a bacterial nucleotide exchange factor that is important for regulation of protein folding machinery, as well as the heat shock response. It is a heat-inducible protein and during stress it prevents unfolded proteins from accumulating in the cytoplasm. Accumulation of unfolded proteins in the cytoplasm can lead to cell death.

References

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  13. ↑ Katayama T, Kubota T, Kurokawa K, Crooke E, Sekimizu K (July 1998). "The initiator function of DnaA protein is negatively regulated by the sliding clamp of the E. coli chromosomal replicase". Cell. 94 (1): 61–71. doi: 10.1016/S0092-8674(00)81222-2 . PMID   9674428. S2CID   15215988.
  14. ↑ Kato J, Katayama T (August 2001). "Hda, a novel DnaA-related protein, regulates the replication cycle in Escherichia coli". The EMBO Journal. 20 (15): 4253–4262. doi:10.1093/emboj/20.15.4253. PMC   149159 . PMID   11483528.
  15. ↑ Kasho K, Katayama T (January 2013). "DnaA binding locus datA promotes DnaA-ATP hydrolysis to enable cell cycle-coordinated replication initiation". Proceedings of the National Academy of Sciences of the United States of America. 110 (3): 936–941. Bibcode:2013PNAS..110..936K. doi: 10.1073/pnas.1212070110 . PMC   3549119 . PMID   23277577.
  16. ↑ Fujimitsu K, Senriuchi T, Katayama T (May 2009). "Specific genomic sequences of E. coli promote replicational initiation by directly reactivating ADP-DnaA". Genes & Development. 23 (10): 1221–1233. doi:10.1101/gad.1775809. PMC   2685538 . PMID   19401329.
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