Sgs1: Difference between revisions

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'''Sgs1''', also known as '''slow growth suppressor 1''',<ref>{{cite journal | title=The yeast type I topoisomerase Top3 interacts with Sgs1, a DNA helicase homolog: a potential eukaryotic reverse gyrase | last=Gangloff | first=S et al | journal=Molecular and Cellular Biology |date=December 1994 | volume=14 | issue=12 | pagepages=8391–8398 | pmc=359378 | pmid=7969174|display-authors=etal | doi=10.1128/mcb.14.12.8391 }}</ref> is a DNA [[helicase]] protein found in ''[[Saccharomyces cerevisiae]]''. It is a [[Homology (biology)#Homology of sequences in genetics|homolog]] of the bacterial [[RecQ]] helicase. Like the other members of the RecQ helicase family, Sgs1 is important for [[DNA repair]]. In particular, Sgs1 collaborates with other proteins to repair double-strand breaks during [[Homologous recombination#In eukaryotes|homologous recombination]] in eukaryotes.<ref>{{cite journal | title=Sae2, Exo1 and Sgs1 collaborate in DNA double-strand break processing | last1=Mimitou | first1=EP | last2=Symington | first2=LS | date=9 October 2008| volume=455 | issue=7214 | pages=770–774 | doi=10.1038/nature07312 | pmid=18806779| pmc=3818707 | journal=Nature | bibcode=2008Natur.455..770M }}</ref>

The Sgs1([[Bloom syndrome protein|BLM]]) helicase is an [[Homology (biology)#Orthology|ortholog]] of the human [[Bloom syndrome protein]]. It appears to be a central regulator of most of the [[Genetic recombination|recombination]] events that occur during ''S. cerevisiae'' [[meiosis]].<ref name=De>{{vcite2cite journal |vauthors=De Muyt A, Jessop L, Kolar E, Sourirajan A, Chen J, Dayani Y, Lichten M |title=BLM helicase ortholog Sgs1 is a central regulator of meiotic recombination intermediate metabolism |journal=Mol. Cell |volume=46 |issue=1 |pages=43–53 |year=2012 |pmid=22500736 |pmc=3328772 |doi=10.1016/j.molcel.2012.02.020 |url=}}</ref> During normal [[meiosis]] Sgs1(BLM) is responsible for directing recombination towards the alternate formation of either early non-crossover recombinants (NCOs) or [[Holliday junction]] joint molecules, the latter being subsequently resolved as crossovers (COs) (see Figure).<ref name=De /> The several roles of Sgs1 in meiotic recombination were reviewed by Klein and Symington.<ref name="pmid22500794">{{vcite2cite journal |vauthors=Klein HL, Symington LS |title=Sgs1--the maestro of recombination |journal=Cell |volume=149 |issue=2 |pages=257–9 |year=2012 |pmid=22500794 |doi=10.1016/j.cell.2012.03.020 |urldoi-access=free }}</ref> Primarily, Sgs1 displaces the strand invasion intermediate that initiates recombination, thus facilitating NCO recombination (see [[Homologous recombination]] and [[Bloom syndrome protein]]).

Sgs1 also has a role in a pathway leading to CO recombinants. Sgs1 together with [[EXO1]] and [[MLH1]]-[[MLH3]] heterodimer (MutL gamma) define a joint molecule resolution pathway that produces the majority of crossovers in budding yeast, and by inference, in mammals.<ref name="pmid22500800">{{vcite2cite journal |vauthors=Zakharyevich K, Tang S, Ma Y, Hunter N |title=Delineation of joint molecule resolution pathways in meiosis identifies a crossover-specific resolvase |journal=Cell |volume=149 |issue=2 |pages=334–47 |year=2012 |pmid=22500800 |pmc=3377385 |doi=10.1016/j.cell.2012.03.023 |url=}}</ref>