Journal
JOURNAL OF MOLECULAR BIOLOGY
Volume 425, Issue 23, Pages 4802-4819Publisher
ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jmb.2013.08.021
Keywords
single stranded DNA binding protein; SSB; DNA replication; DNA repair; DNA binding
Categories
Funding
- National Institutes of Health [GM30498]
- National Science Foundation
- Div Of Molecular and Cellular Bioscience
- Direct For Biological Sciences [1329285] Funding Source: National Science Foundation
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Escherichia coli single-stranded DNA binding protein (SSB) plays essential roles in DNA replication, recombination and repair. SSB functions as a homotetramer with each subunit possessing a DNA binding domain (OB-fold) and an intrinsically disordered C-terminus, of which the last nine amino acids provide the site for interaction with at least a dozen other proteins that function in DNA metabolism. To examine how many C-termini are needed for SSB function, we engineered covalently linked forms of SSB that possess only one or two C-termini within a four-OB-fold tetramer. Whereas E. coli expressing SSB with only two tails can survive, expression of a single-tailed SSB is dominant lethal. E. coli expressing only the two-tailed SSB recovers faster from exposure to DNA damaging agents but accumulates more mutations. A single-tailed SSB shows defects in coupled leading and lagging strand DNA replication and does not support replication restart in vitro. These deficiencies in vitro provide a plausible explanation for the lethality observed in vivo. These results indicate that a single SSB tetramer must interact simultaneously with multiple protein partners during some essential roles in genome maintenance. (C) 2013 Elsevier Ltd. All rights reserved.
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