UvrABC endonuclease
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193531127
2008-02-23T18:43:37Z
199.8.26.10
Changed "and" to "an" to fix error.
'''UvrABC endonuclease''' is a multienzyme complex in [[E.coli]] bacteria involved in [[DNA repair]] mechanism 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 12 nucleotides where a genetic mutation has occurred followed by a DNA polymerase replacing these aberrant nucleotides with the correct nucleotides and completing the [[DNA repair]]. This enzyme complex is able to repair many different types of damage, including [[cyclobutyl dimer]] formation.
==Mechanism:==
# Two UvrA proteins form a dimer and they both have ATPase/GTPase activity.
# The UvrA [[dimer]] binds with UvrB and forms a [[trimer]] which 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]].
# The UvrB part of the trimer attaches to the double helix at the damaged site.
# The UvrA dimer leaves and an UvrC protein comes in and binds to the UvrB [[monomer]] and hence froms a new UvrBC dimer.
# This dimer is responsible for [[cleaving]] the nucleotides either side of the DNA damage. UvrB cleaves a [[phosphodiester bond]] 5 nucleotides downstream of the DNA damage, and the UvrC cleaves a [[phosphodiester bond]] 8 nucleotides upstream of the DNA damage and created 12 nucleotide excised segment.
# [[DNA helicase]] II (sometimes called UvrD) then comes in and removes the excised segment by removing the base pairing. The UvrB still remain in place even though UvrC has disassociated at this stage, as UvrB may be involved in the preventing of the [[reannealing]] of the [[excised DNA]].
#[[DNA polymerase I]] comes in and fills in the correct nucleotides sequence and the last phosphodiester bond is completed by DNA ligase.
==See also==
*[[DNA repair]]
*[[endonuclease]]
*[[Nucleotide excision repair]]
*[[DNA]]
==External links==
* {{MeshName|uvrABC+endonuclease}}
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