Sgs1, also known as slow growth suppressor 1, is a DNA

helicase Helicases are a class of enzymes thought to be vital to all organisms. Their main function is to unpack an organism's genetic material. Helicases are motor proteins that move directionally along a nucleic acid phosphodiester backbone, separatin ...

protein found in ''

Saccharomyces cerevisiae ''Saccharomyces cerevisiae'' () (brewer's yeast or baker's yeast) is a species of yeast (single-celled fungus microorganisms). The species has been instrumental in winemaking, baking, and brewing since ancient times. It is believed to have been o ...

''. It is a

homolog In biology, homology is similarity due to shared ancestry between a pair of structures or genes in different taxa. A common example of homologous structures is the forelimbs of vertebrates, where the wings of bats and birds, the arms of prima ...

of the bacterial

RecQ RecQ helicase is a family of helicase enzymes initially found in ''Escherichia coli'' that has been shown to be important in genome maintenance. They function through catalyzing the reaction ATP + H2O → ADP + P and thus driving the unwind ...

helicase. Like the other members of the RecQ helicase family, Sgs1 is important for

DNA repair DNA repair is a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. In human cells, both normal metabolic activities and environmental factors such as radiation can cause DNA dam ...

. In particular, Sgs1 collaborates with other proteins to repair double-strand breaks during

homologous recombination Homologous recombination is a type of genetic recombination in which genetic information is exchanged between two similar or identical molecules of double-stranded or single-stranded nucleic acids (usually DNA as in cellular organisms but may ...

in eukaryotes.

Meiosis

The Sgs1(

BLM BLM most commonly refers to: * Black Lives Matter, an international anti-racism movement and organization * Bureau of Land Management, a U.S. federal government agency BLM may also refer to: Organizations * BLM (law firm), United Kingdom and ...

) helicase is an

ortholog Sequence homology is the biological homology between DNA, RNA, or protein sequences, defined in terms of shared ancestry in the evolutionary history of life. Two segments of DNA can have shared ancestry because of three phenomena: either a spec ...

of the human

Bloom syndrome protein Bloom syndrome protein is a protein that in humans is encoded by the ''BLM'' gene and is not expressed in Bloom syndrome. The Bloom syndrome gene product is related to the RecQ subset of DExH box-containing DNA helicases and has both DNA-stimula ...

. It appears to be a central regulator of most of the recombination events that occur during ''S. cerevisiae''

meiosis Meiosis (; , since it is a reductional division) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, such as sperm or egg cells. It involves two rounds of division that ultimately resu ...

. During normal

Sgs1(BLM) is responsible for directing recombination towards the alternate formation of either early non-crossover recombinants (NCOs) or

Holliday junction A Holliday junction is a branched nucleic acid structure that contains four double-stranded arms joined. These arms may adopt one of several conformations depending on buffer salt concentrations and the sequence of nucleobases closest to the ju ...

joint molecules, the latter being subsequently resolved as crossovers (COs) (see Figure). The several roles of Sgs1 in meiotic recombination were reviewed by Klein and Symington. Primarily, Sgs1 displaces the strand invasion intermediate that initiates recombination, thus facilitating NCO recombination (see

Homologous recombination Homologous recombination is a type of genetic recombination in which genetic information is exchanged between two similar or identical molecules of double-stranded or single-stranded nucleic acids (usually DNA as in cellular organisms but may ...

and

). Sgs1 also has a role in a pathway leading to CO recombinants. Sgs1 together with

EXO1 Exonuclease 1 is an enzyme that in humans is encoded by the ''EXO1'' gene. This gene encodes a protein with 5' to 3' exonuclease activity as well as RNase activity (endonuclease activity cleaving RNA on DNA/RNA hybrid). It is similar to the Saccha ...

and

MLH1 DNA mismatch repair protein Mlh1 or MutL protein homolog 1 is a protein that in humans is encoded by the MLH1 gene located on chromosome 3. It is a gene commonly associated with hereditary nonpolyposis colorectal cancer. Orthologs of human MLH1 h ...

MLH3 DNA mismatch repair protein Mlh3 is a protein that in humans is encoded by the ''MLH3'' gene. Function This gene is a member of the MutL-homolog (MLH) family of DNA mismatch repair (MMR) genes. MLH genes are implicated in maintaining genomic in ...

heterodimer (MutL gamma) define a joint molecule resolution pathway that produces the majority of crossovers in budding yeast, and by inference, in mammals.

References

{{Reflist DNA repair