Specific basic patch‐dependent multimerization of Saccharomyces cerevisiae ORC on single‐stranded DNA promotes ATP hydrolysis

• Published in: Genes to cells : devoted to molecular & cellular mechanisms Vol. 24; no. 9; pp. 608 - 618
• Main Authors: Kawakami, Hironori, Muraoka, Ryuya, Ohashi, Eiji, Kawabata, Kenta, Kanamoto, Shota, Chichibu, Takeaki, Tsurimoto, Toshiki, Katayama, Tsutomu
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01.09.2019
• Subjects: AAA+; Adenine; Adenosine triphosphatase; Adenosine Triphosphate - metabolism; ATPase; Deoxyribonucleic acid; DNA; DNA biosynthesis; DNA helicase; DNA Replication; DNA, Single-Stranded - metabolism; Gene loci; Genomics; Heredity; Hydrolysis; intrinsically disordered region; Nucleotides; origin recognition complex; Origin Recognition Complex - metabolism; Protein Binding; Protein Multimerization; Replication initiation; Replication Origin; Replication origins; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins - metabolism; single‐stranded DNA; origin recognition complex; DNA replication; single-stranded DNA; AAA+; ATPase; intrinsically disordered region; protein multimerization
• ISSN: 1356-9597; 1365-2443
• DOI: 10.1111/gtc.12710

Replication initiation at specific genomic loci dictates precise duplication and inheritance of genetic information. In eukaryotic cells, ATP‐bound origin recognition complexes (ORCs) stably bind to double‐stranded (ds) DNA origins to recruit the replicative helicase onto the origin DNA. To achieve these processes, an essential region of the origin DNA must be recognized by the eukaryotic origin sensor (EOS) basic patch within the disordered domain of the largest ORC subunit, Orc1. Although ORC also binds single‐stranded (ss) DNA in an EOS‐independent manner, it is unknown whether EOS regulates ORC on ssDNA. We found that, in budding yeast, ORC multimerizes on ssDNA in vitro independently of adenine nucleotides. We also found that the ORC multimers form in an EOS‐dependent manner and stimulate the ORC ATPase activity. An analysis of genomics data supported the idea that ORC‐ssDNA binding occurs in vivo at specific genomic loci outside of replication origins. These results suggest that EOS function is differentiated by ORC‐bound ssDNA, which promotes ORC self‐assembly and ATP hydrolysis. These mechanisms could modulate ORC activity at specific genomic loci and could be conserved among eukaryotes. ORC homomultimerizes on ssDNA. The EOS basic patch, originally identified as the origin DNA sensor, acquires a novel role in ORC multimerization on ssDNA, which could modulate ORC activity at specific genomic loci and could be highly conserved among eukaryotes.