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An essential role for Orc6 in DNA replication through maintenance of pre‐replicative complexes
Author(s) -
Semple Jeffrey W,
DaSilva Lance F,
Jervis Eric J,
AhKee Jennifer,
AlAttar Hyder,
Kummer Lutz,
Heikkila John J,
Pasero Philippe,
Duncker Bernard P
Publication year - 2006
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7601391
Subject(s) - biology , origin recognition complex , microbiology and biotechnology , dna replication , cytokinesis , control of chromosome duplication , pre replication complex , cell cycle , mitosis , dna replication factor cdt1 , cell division , chromatin , eukaryotic dna replication , origin of replication , licensing factor , dna , s phase , genetics , cell
The heterohexameric origin recognition complex (ORC) acts as a scaffold for the G 1 phase assembly of pre‐replicative complexes (pre‐RC). Only the Orc1‐5 subunits appear to be required for origin binding in budding yeast, yet Orc6 is an essential protein for cell proliferation. Imaging of Orc6‐YFP in live cells revealed a punctate pattern consistent with the organization of replication origins into subnuclear foci. Orc6 was not detected at the site of division between mother and daughter cells, in contrast to observations for metazoans, and is not required for mitosis or cytokinesis. An essential role for Orc6 in DNA replication was identified by depleting it at specific cell cycle stages. Interestingly, Orc6 was required for entry into S phase after pre‐RC formation, in contrast to previous models suggesting ORC is dispensable at this point in the cell cycle. When Orc6 was depleted in late G 1 , Mcm2 and Mcm10 were displaced from chromatin, cells failed to progress through S phase, and DNA combing analysis following bromodeoxyuridine incorporation revealed that the efficiency of replication origin firing was severely compromised.