dnaQ is the gene encoding the ε subunit of DNA polymerase III in Escherichia coli. The ε subunit is one of three core proteins in the DNA polymerase complex. It functions as a 3’→5’ DNA directed proofreading exonuclease that removes incorrectly incorporated bases during replication. dnaQ may also be referred to as mutD.
Prokaryotic translation is the process by which messenger RNA is translated into proteins in prokaryotes.
The gene rpoS encodes the sigma factor sigma-38, a 37.8 kD protein in Escherichia coli. Sigma factors are proteins that regulate transcription in bacteria. Sigma factors can be activated in response to different environmental conditions. rpoS is transcribed in late exponential phase, and RpoS is the primary regulator of stationary phase genes. RpoS is a central regulator of the general stress response and operates in both a retroactive and a proactive manner: it not only allows the cell to survive environmental challenges, but it also prepares the cell for subsequent stresses (cross-protection). The transcriptional regulator CsgD is central to biofilm formation, controlling the expression of the curli structural and export proteins, and the diguanylate cyclase, adrA, which indirectly activates cellulose production. The rpoS gene most likely originated in the gammaproteobacteria.
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.
The C0343 RNA is a bacterial non-coding RNA of 74 nucleotides in length that is found between the ydaN and dbpA genes in the genomes of Escherichia coli and Shigella flexneri, Salmonella enterica and Salmonella typhimurium. This ncRNA was originally identified in E.coli using high-density oligonucleotide probe arrays (microarray). The function of this ncRNA is unknown.
The C0465 RNA is a bacterial non-coding RNA of 78 nucleotides in length that is found between the tar and cheW genes in the genomes of Escherichia coli and Shigella flexneri. This ncRNA was originally identified in E.coli using high-density oligonucleotide probe arrays (microarray). The function of this ncRNA is unknown.
The C0719 RNA is a bacterial non-coding RNA of 222 nucleotides in length that is found between the yghK and glcB genes in the genomes of Escherichia coli and Shigella flexneri. This non-coding RNA was originally identified in E.coli using high-density oligonucleotide probe arrays (microarray.) The function of this ncRNA is unknown.
The 245 nucleotide sRNA of Escherichia coli, CsrC, was discovered using a genetic screen for factors that regulate glycogen biosynthesis. CsrC RNA binds multiple copies of CsrA, a protein that post-transcriptionally regulates central carbon flux, biofilm formation and motility in E. coli. CsrC antagonises the regulatory effects of CsrA, presumably by sequestering this protein. The discovery of CsrC is intriguing, in that a similar sRNA, CsrB, performs essentially the same function. Both sRNAs possess similar imperfect repeat sequences, primarily localised in the loops of predicted hairpins, which may serve as CsrA binding elements. Transcription of csrC increases as the culture approaches the stationary phase of growth and is indirectly activated by CsrA via the response regulator UvrY [1]. This RNA was also discovered in E. coli during a large scale screen [2]. The gene called SraK, was highly abundant in stationary phase, but low levels could be detected in exponentially growing cells as well [2].
The gcvB RNA gene encodes a small non-coding RNA involved in the regulation of a number of amino acid transport systems as well as amino acid biosynthetic genes. The GcvB gene is found in enteric bacteria such as Escherichia coli. GcvB regulates genes by acting as an antisense binding partner of the mRNAs for each regulated gene. This binding is dependent on binding to a protein called Hfq. Transcription of the GcvB RNA is activated by the adjacent GcvA gene and repressed by the GcvR gene. A deletion of GcvB RNA from Y. pestis changed colony shape as well as reducing growth. It has been shown by gene deletion that GcvB is a regulator of acid resistance in E. coli. GcvB enhances the ability of the bacterium to survive low pH by upregulating the levels of the alternate sigma factor RpoS. A polymeric form of GcvB has recently been identified. Interaction of GcvB with small RNA SroC triggers the degradation of GcvB by RNase E, lifting the GcvB-mediated mRNA repression of its target genes.
The IS102 RNA is a non-coding RNA that is found in bacteria such as Shigella flexneri and Escherichia coli. The RNA is 208 nucleotides in length and found between the yeeP and flu genes. This RNA was identified in a computational screen of E. coli. The function of this RNA is unknown.
The IS128 RNA is a non-coding RNA found in bacteria such as Escherichia coli and Shigella flexneri. The RNA is 209 nucleotides in length. It is found between the sseA and sseB genes. The IS128 RNA was initially identified in a computational screen of the E. coli genome. The function of this RNA is unknown.
The MicC non-coding RNA is located between the ompN and ydbK genes in E. coli. This Hfq-associated RNA is thought to be a regulator of the expression level of the OmpC porin protein, with a 5' region of 22 nucleotides potentially forming an antisense interaction with the ompC mRNA. Along with MicF RNA this family may act in conjunction with EnvZ-OmpR two-component system to control the OmpF/OmpC protein ratio in response to a variety of environmental stimuli. The expression of micC was shown to be increased in the presence of beta-lactam antibiotics.
Sib RNA refers to a group of related non-coding RNA. They were originally named QUAD RNA after they were discovered as four repeat elements in Escherichia coli intergenic regions. The family was later renamed Sib when it was discovered that the number of repeats is variable in other species and in other E. coli strains.
RyhB RNA is a 90 nucleotide RNA that down-regulates a set of iron-storage and iron-using proteins when iron is limiting; it is itself negatively regulated by the ferric uptake repressor protein, Fur.
Spot 42 RNA is a regulatory non-coding bacterial small RNA encoded by the spf gene. Spf is found in gammaproteobacteria and the majority of experimental work on Spot42 has been performed in Escherichia coli and recently in Aliivibrio salmonicida. In the cell Spot42 plays essential roles as a regulator in carbohydrate metabolism and uptake, and its expression is activated by glucose, and inhibited by the cAMP-CRP complex.
GlmZ is a small non-coding RNA (ncRNA). It is the functional product of a gene which is not translated into protein.
The gal operon is a prokaryotic operon, which encodes enzymes necessary for galactose metabolism. The operon contains two operators, OE and OI. The former is just before the promoter, and the latter is just after the galE gene.
Escherichia coli contains a number of small RNAs located in intergenic regions of its genome. The presence of at least 55 of these has been verified experimentally. 275 potential sRNA-encoding loci were identified computationally using the QRNA program. These loci will include false positives, so the number of sRNA genes in E. coli is likely to be less than 275. A computational screen based on promoter sequences recognised by the sigma factor sigma 70 and on Rho-independent terminators predicted 24 putative sRNA genes, 14 of these were verified experimentally by northern blotting. The experimentally verified sRNAs included the well characterised sRNAs RprA and RyhB. Many of the sRNAs identified in this screen, including RprA, RyhB, SraB and SraL, are only expressed in the stationary phase of bacterial cell growth. A screen for sRNA genes based on homology to Salmonella and Klebsiella identified 59 candidate sRNA genes. From this set of candidate genes, microarray analysis and northern blotting confirmed the existence of 17 previously undescribed sRNAs, many of which bind to the chaperone protein Hfq and regulate the translation of RpoS. UptR sRNA transcribed from the uptR gene is implicated in suppressing extracytoplasmic toxicity by reducing the amount of membrane-bound toxic hybrid protein.
The gene rpoE encodes the sigma factor sigma-24, a protein in Escherichia coli and other species of bacteria. Depending on the bacterial species, this gene may be referred to as sigE.
