| DNA pol III theta subunit | |||||||
|---|---|---|---|---|---|---|---|
| Identifiers | |||||||
| Organism | |||||||
| Symbol | holE | ||||||
| Entrez | 947471 | ||||||
| RefSeq (Prot) | NP_416356.1 | ||||||
| UniProt | P0ABS8 | ||||||
| Other data | |||||||
| EC number | 2.7.7.7 | ||||||
| Chromosome | genome: 1.92 - 1.92 Mb | ||||||
| |||||||
| DNA polymerase III, theta subunit | |||||||||
|---|---|---|---|---|---|---|---|---|---|
 structure of the e. coli pol iii epsilon-hot proofreading complex | |||||||||
| Identifiers | |||||||||
| Symbol | DNA_pol3_theta | ||||||||
| Pfam | PF06440 | ||||||||
| InterPro | IPR009052 | ||||||||
| SCOP2 | 1du2 / SCOPe / SUPFAM | ||||||||
| |||||||||
In E. coli and other bacteria, holE is a gene that encodes the theta subunit of DNA polymerase III. [1]
In molecular biology, RNA polymerase, is an enzyme that synthesizes RNA from a DNA template.
A DNA polymerase is a member of a family of enzymes that catalyze the synthesis of DNA molecules from nucleoside triphosphates, the molecular precursors of DNA. These enzymes are essential for DNA replication and usually work in groups to create two identical DNA duplexes from a single original DNA duplex. During this process, DNA polymerase "reads" the existing DNA strands to create two new strands that match the existing ones. These enzymes catalyze the chemical reaction
DNA polymerase I is an enzyme that participates in the process of prokaryotic DNA replication. Discovered by Arthur Kornberg in 1956, it was the first known DNA polymerase. It was initially characterized in E. coli and is ubiquitous in prokaryotes. In E. coli and many other bacteria, the gene that encodes Pol I is known as polA. The E. coli form of the enzyme is composed of 928 amino acids, and is an example of a processive enzyme—it can sequentially catalyze multiple polymerisations without releasing the single-stranded template. The physiological function of Pol I is mainly to repair any damage with DNA, but it also serves to connect Okazaki fragments by deleting RNA primers and replacing the strand with DNA.
DNA polymerase III holoenzyme is the primary enzyme complex involved in prokaryotic DNA replication. It was discovered by Thomas Kornberg and Malcolm Gefter in 1970. The complex has high processivity and, specifically referring to the replication of the E.coli genome, works in conjunction with four other DNA polymerases. Being the primary holoenzyme involved in replication activity, the DNA Pol III holoenzyme also has proofreading capabilities that corrects replication mistakes by means of exonuclease activity reading 3'→5' and synthesizing 5'→3'. DNA Pol III is a component of the replisome, which is located at the replication fork.
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.
RNA polymerase II is a multiprotein complex that transcribes DNA into precursors of messenger RNA (mRNA) and most small nuclear RNA (snRNA) and microRNA. It is one of the three RNAP enzymes found in the nucleus of eukaryotic cells. A 550 kDa complex of 12 subunits, RNAP II is the most studied type of RNA polymerase. A wide range of transcription factors are required for it to bind to upstream gene promoters and begin transcription.
DNA polymerase II is a prokaryotic DNA-Dependent DNA polymerase encoded by the PolB gene.
Genomic deoxyribonucleic acid is chromosomal DNA, in contrast to extra-chromosomal DNAs like plasmids. It is also then abbreviated as gDNA. Most organisms have the same genomic DNA in every cell; however, only certain genes are active in each cell to allow for cell function and differentiation within the body.
DnaE, the gene product of dnaE, is the catalytic α subunit of DNA polymerase III, acting as a DNA polymerase. This enzyme is only found in prokaryotes.
DNA polymerase subunit gamma is an enzyme that in humans is encoded by the POLG gene. Mitochondrial DNA polymerase is heterotrimeric, consisting of a homodimer of accessory subunits plus a catalytic subunit. The protein encoded by this gene is the catalytic subunit of mitochondrial DNA polymerase. Defects in this gene are a cause of progressive external ophthalmoplegia with mitochondrial DNA deletions 1 (PEOA1), sensory ataxic neuropathy dysarthria and ophthalmoparesis (SANDO), Alpers-Huttenlocher syndrome (AHS), and mitochondrial neurogastrointestinal encephalopathy syndrome (MNGIE).
DNA polymerase theta is an enzyme that in humans is encoded by the POLQ gene. This polymerase plays a key role in one of the three major double strand break repair pathways: theta-mediated end joining. Most double-strand breaks are repaired by non-homologous end joining (NHEJ) or homology directed repair (HDR). However, in some contexts, NHEJ and HR are insufficient and TMEJ is the only solution to repair the break. TMEJ is often described as alternative NHEJ, but differs in that it lacks a requirement for the Ku heterodimer, and it can only act on resected DNA ends. Following annealing of short regions on the DNA overhangs, DNA polymerase theta catalyzes template-dependent DNA synthesis across the broken ends, stabilizing the paired structure.
Zinc finger protein 143 is a protein that in humans is encoded by the ZNF143 gene.
DNA polymerase eta, is a protein that in humans is encoded by the POLH gene.
Microhomology-mediated end joining (MMEJ), also known as alternative nonhomologous end-joining (Alt-NHEJ) is one of the pathways for repairing double-strand breaks in DNA. As reviewed by McVey and Lee, the foremost distinguishing property of MMEJ is the use of microhomologous sequences during the alignment of broken ends before joining, thereby resulting in deletions flanking the original break. MMEJ is frequently associated with chromosome abnormalities such as deletions, translocations, inversions and other complex rearrangements.
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.
In molecular biology, the δ (delta) subunit of DNA polymerase III is encoded by the holA gene in E. coli and other bacteria. Along with the γ, δ', χ, and ψ subunits that make up the core polymerase, and the β accessory proteins, the δ subunit is responsible for the high speed and processivity of polIII.
In E. coli and other bacteria, holB is a gene that encodes the delta prime subunit of DNA polymerase III.
In E. coli and other bacteria, holC is a gene that encodes the chi subunit of DNA polymerase III.
In E. coli and other bacteria, holD is a gene that encodes the psi subunit of DNA polymerase III.
Riboviria is a realm of viruses that includes all viruses that use an RNA-dependent polymerase for replication. It includes RNA viruses that encode an RNA-dependent RNA polymerase; and, it includes reverse-transcribing viruses that encode an RNA-dependent DNA polymerase. RNA-dependent RNA polymerase (RdRp), also called RNA replicase, produces RNA from RNA. RNA-dependent DNA polymerase (RdDp), also called reverse transcriptase (RT), produces DNA from RNA. These enzymes are essential for replicating the viral genome and transcribing viral genes into messenger RNA (mRNA) for translation of viral proteins.
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