UvrABC endonuclease

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UvrABC system protein A
Identifiers
Organism Escherichia coli (strain K12)
SymboluvrA
Entrez 948559
RefSeq (Prot) NP_418482.1
UniProt P0A698
Other data
EC number 3.6.1.3
Chromosome genomic: 4.27 - 4.27 Mb
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Structures Swiss-model
Domains InterPro
UvrABC system protein B
Identifiers
Organism Escherichia coli (strain K12)
SymboluvrB
Entrez 945385
RefSeq (Prot) NP_415300.1
UniProt P0A8F8
Other data
Chromosome genomic: 0.81 - 0.82 Mb
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Structures Swiss-model
Domains InterPro
UvrABC system protein C
Identifiers
Organism Escherichia coli (strain K12)
SymboluvrC
Entrez 947203
RefSeq (Prot) NP_416423.4
UniProt P0A8G0
Other data
Chromosome genomic: 1.99 - 1.99 Mb
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Structures Swiss-model
Domains InterPro

UvrABC endonuclease is a multienzyme complex in bacteria involved in DNA repair by nucleotide excision repair, and it is, therefore, sometimes called an excinuclease. This UvrABC repair process, sometimes called the short-patch process, involves the removal of twelve nucleotides where a DNA damage has occurred followed by a DNA polymerase, replacing these aberrant nucleotides with the correct nucleotides and completing the DNA repair. The subunits for this enzyme are encoded in the uvrA, uvrB, and uvrC genes. This enzyme complex is able to repair many different types of damage, including cyclobutyl dimer formation. [1]

Contents

Mechanism

  1. Two UvrA proteins form a homodimer (UvrA2) and they both have ATPase/GTPase activity.
  2. Two UvrB proteins form a homodimer (UvrB2).
  3. The UvrA homodimer binds with a UvrB homodimer (UvrA2B2) [2] and forms a complex that is able to detect DNA damage. The UvrA dimer functions as the unit responsible for the detection of DNA damage, probably through a mechanism of detecting distortions in the DNA double helix.
  4. Upon binding of the UvrA2B2 complex to a putative damaged site, the DNA wraps around UvrB [3]
  5. The UvrA dimer leaves and a UvrC protein comes in and binds to the UvrB and, hence, forms a new UvrBC complex.
  6. UvrC is responsible for cleaving the nucleotides either side of the DNA damage. [4] It cleaves a phosphodiester bond four nucleotides downstream of the DNA damage, and cleaves a phosphodiester bond eight nucleotides upstream of the DNA damage and creates a twelve nucleotide excised segment.
  7. DNA helicase II (sometimes called UvrD) then comes in and removes the excised segment by removing the base pairing. The UvrB still remains in place even though UvrC has disassociated at this stage, as UvrB may be involved to prevent the reannealing of the excised DNA.
  8. DNA polymerase I comes in and fills in the correct nucleotides sequence, kicking off UvrB in the process, and the last phosphodiester bond is completed by DNA ligase.

Although most of the studies on the UvrABC endonuclease were carried out with the gram negative bacterium Escherichia coli , similar studies have also been reported for the archaeal bacterium Halobacterium sp. NRC-1. [5] Investigation of DNA repair in this archaeal halobacterium is important for understanding the diversity and evolution of DNA repair systems generally. In Halobacterium sp. NRC-1, homologs of the E. coli bacterial nucleotide excision repair genes uvrA, uvrB and uvrC are required tor the removal of UV damages (in the absence of photoreactivating light). [5]

See also

References

  1. ↑ Grossman L, Yeung AT (1990). "The UvrABC endonuclease system of Escherichia coli--a view from Baltimore". Mutation Research. 236 (2–3): 213–221. doi:10.1016/0921-8777(90)90006-q. PMID   2144612.
  2. ↑ Verhoeven EE, Wyman C, Moolenaar GF, Goosen N (August 2002). "The presence of two UvrB subunits in the UvrAB complex ensures damage detection in both DNA strands". The EMBO Journal. 21 (15): 4196–4205. doi:10.1093/emboj/cdf396. PMC   126143 . PMID   12145219.
  3. ↑ "uvrB – UvrABC system protein B – Escherichia coli (strain K12) – uvrB gene & protein". www.uniprot.org. Retrieved 28 February 2016.
  4. ↑ Verhoeven EE, van Kesteren M, Moolenaar GF, Visse R, Goosen N (February 2000). "Catalytic sites for 3' and 5' incision of Escherichia coli nucleotide excision repair are both located in UvrC". The Journal of Biological Chemistry. 275 (7): 5120–5123. doi: 10.1074/jbc.275.7.5120 . hdl: 1887/49954 . PMID   10671556.
  5. 1 2 Crowley DJ, Boubriak I, Berquist BR, Clark M, Richard E, Sullivan L, DasSarma S, McCready S. The uvrA, uvrB and uvrC genes are required for repair of ultraviolet light induced DNA photoproducts in Halobacterium sp. NRC-1. Saline Syst. 2006 Sep 13;2:11. doi: 10.1186/1746-1448-2-11. PMID 16970815; PMCID: PMC1590041.


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