ATP-dependent helicase SGS1

UniProtKB accession:  P35187

Grouped By:  Matching UniProtKB accession

UniProtKB description:  ATP-dependent 3'-5' DNA helicase able to unwind duplex DNA or DNA:RNA heteroduplex (PubMed:8878475, PubMed:9545297). Unwinds G-quadruplex DNA; unwinding occurs in the 3'-5' direction, requires a 3' single-stranded end of at least 7 nucleotides (PubMed:10198430). Helicase activity is higher on G-quadruplex substrates than on duplex DNA substrates (PubMed:10198430). Assayed with a catalytic fragment (residues 400-1268) (PubMed:10198430). Telomeres and rDNA are notably G-rich; formation of G-quadruplex DNA would block DNA replication and transcription (PubMed:10198430). Acts as an integral component of the S-phase checkpoint response, which arrests cells due to DNA damage or blocked fork progression during DNA replication (PubMed:10640278). Can create a deleterious topological substrate that TOP3 preferentially resolves. The TOP3-SGS1 protein complex may function as a eukaryotic reverse gyrase introducing positive supercoils into extrachromosomal ribosomal DNA rings (PubMed:7969174). Together with topoisomerase II has a role in chromosomal segregation (PubMed:7736577). Maintains rDNA structure where it has a role in re-starting stalled replication forks (PubMed:12228808).