The origin recognition complex interacts with a subset of metabolic genes tightly linked to origins of replication.
The origin recognition complex (ORC) marks chromosomal sites as replication origins and is essential for replication initiation. In yeast, ORC also binds to DNA elements called silencers, where its primary function is to recruit silent information regulator (SIR) proteins to establish transcriptional silencing. Indeed, silencers function poorly as chromosomal origins. Several genetic, molecular, and biochemical studies of HMR-E have led to a model proposing that when ORC becomes limiting in the cell (such as in the orc2-1 mutant) only sites that bind ORC tightly (such as HMR-E) remain fully occupied by ORC, while lower affinity sites, including many origins, lose ORC occupancy. Since HMR-E possessed a unique non-replication function, we reasoned that other tight sites might reveal novel functions for ORC on chromosomes. Therefore, we comprehensively determined ORC "affinity" genome-wide by performing an ORC ChIP-on-chip in ORC2 and orc2-1 strains. Here we describe a novel group of orc2-1-resistant ORC-interacting chromosomal sites (ORF-ORC sites) that did not function as replication origins or silencers. Instead, ORF-ORC sites were comprised of protein-coding regions of highly transcribed metabolic genes. In contrast to the ORC-silencer paradigm, transcriptional activation promoted ORC association with these genes. Remarkably, ORF-ORC genes were enriched in proximity to origins of replication and, in several instances, were transcriptionally regulated by these origins. Taken together, these results suggest a surprising connection among ORC, replication origins, and cellular metabolism.
Shor
Erika
E
Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin, United States of America.
Warren
Christopher L
CL
Tietjen
Joshua
J
Hou
Zhonggang
Z
Müller
Ulrika
U
Alborelli
Ilaria
I
Gohard
Florence H
FH
Yemm
Adrian I
AI
Borisov
Lev
L
Broach
James R
JR
Weinreich
Michael
M
Nieduszynski
Conrad A
CA
Ansari
Aseem Z
AZ
Fox
Catherine A
CA
D001665:Binding Sites; D047369:Chromatin Immunoprecipitation; D015825:Chromosomes, Fungal / Q000235:genetics; D015966:Gene Expression Regulation, Fungal; D053858:Metabolic Networks and Pathways / Q000235:genetics*; D016366:Open Reading Frames / Q000235:genetics; D051738:Origin Recognition Complex / Q000378:metabolism*; D011485:Protein Binding; D018741:Replication Origin / Q000235:genetics*; D015203:Reproducibility of Results; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D017384:Sequence Deletion; D037941:Silencer Elements, Transcriptional / Q000235:genetics; D014158:Transcription, Genetic
D051738:Origin Recognition Complex; D029701:Saccharomyces cerevisiae Proteins