RT Journal
A1 Koren, Amnon
A1 Soifer, Ilya
A1 Barkai, Naama
T1 MRC1-dependent scaling of the budding yeast DNA replication timing program
JF Genome Research 
JO Genome Research 
YR 2010 
FD June 01 
VO 20 
IS 6 
SP 781 
OP 790 
DO 10.1101/gr.102764.109 
UL http://genome.cshlp.org/content/20/6/781.abstract 
AB We describe the DNA replication timing programs of 14 yeast mutants with an extended S phase identified by a novel genome-wide screen. These mutants are associated with the DNA replication machinery, cell-cycle control, and dNTP synthesis and affect different parts of S phase. In 13 of the mutants, origin activation time scales with the duration of S phase. A limited number of origins become inactive in these strains, with inactive origins characterized by small replicons and distributed throughout S phase. In sharp contrast, cells deleted of MRC1, a gene implicated in replication fork stabilization and in the replication checkpoint pathway, maintained wild-type firing times despite over twofold lengthening of S phase. Numerous dormant origins were activated in this mutant. Our data suggest that most perturbations that lengthen S phase affect the entire program of replication timing, rather than a specific subset of origins, maintaining the relative order of origin firing time and delaying firing with relative proportions. Mrc1 emerges as a regulator of this robustness of the replication program.