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Cell cycle‐specific changes in nucleoprotein complexes at a chromosomal replication origin.
Author(s) -
Cassler M. R.,
Grimwade J. E.,
Leonard A. C.
Publication year - 1995
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 - 10.1002/j.1460-2075.1995.tb00271.x
Subject(s) - biology , nucleoprotein , cell cycle , genetics , microbiology and biotechnology , dna replication , replication (statistics) , cell , dna , virology
Initiation of DNA synthesis is triggered by the binding of proteins to replication origins. However, little is known about the order in which specific proteins associate with origin sites during the cell cycle. We show that in cycling cells there are at least two different nucleoprotein complexes at oriC. A factor for inversion stimulation (FIS)‐bound nucleoprotein complex, present throughout the majority of the cell cycle, switches to an integration host factor (IHF)‐bound form as cells initiate DNA replication. Coincident with binding of IHF, initiator DnaA binds to its previously unoccupied R3 site. In stationary phase, a third nucleoprotein complex forms. FIS is absent and inactive oriC forms a nucleoprotein structure containing IHF that is not observed in cycling cells. We propose that interplay between FIS and IHF aids assembly of initiation nucleoprotein complexes during the cell cycle and blocks initiation at inappropriate times. This exchange of components at replication origins is reminiscent of switching between pre‐ and post‐replicative chromatin states at yeast ARS1.