Radiation sensitivity of a mutant of Escherichia coli K-12 associated with DNA replication: Evidence for a new repair function

1976 ◽  
Vol 143 (3) ◽  
pp. 327-332 ◽  
Author(s):  
Brahm S. Srivastava
Keyword(s):  
Escherichia Coli ◽  
Dna Replication ◽  
Radiation Sensitivity ◽  
K 12

scholarly journals Differential Suppression of priA2::kan Phenotypes in Escherichia coli K-12 by Mutations in priA, lexA, and dnaC

Genetics ◽  
1996 ◽  
Vol 143 (1) ◽  
pp. 5-13 ◽  
Author(s):  
Steven J Sandler ◽  
Hardeep S Samra ◽  
Alvin J Clark
Keyword(s):  
Escherichia Coli ◽  
Dna Replication ◽  
Mutant Allele ◽  
Wild Type ◽  
Suppressor Mutations ◽  
Dnab Helicase ◽  
K 12 ◽  
Extragenic Suppressors ◽  
Assembly Activity

Abstract First identified as an essential component of the ϕX174 in vitro DNA replication system, PriA has ATPase, helicase, translocase, and primosome-assembly activities. priA1::kan strains of Escherichia coli are sensitive to UV irradiation, deficient in homologous recombination following transduction, and filamentous. priA2::kan strains have eightfold higher levels of uninduced SOS expression than wild type. We show that (1) priA1::kan strains have eightfold higher levels of uninduced SOS expression, (2) priA2::kan strains are UVS and Rec−, (3) lexA3 suppresses the high basal levels of SOS expression of a priA2::kan strain, and (4) plasmid-encoded priA300 (K230R), a mutant allele retaining only the primosome-assembly activity of priA+, restores both UVR and Rec+ phenotypes to a priA2::kan strain. Finally, we have isolated 17 independent UVR Rec+ revertants of priA2::kan strains that carry extragenic suppressors. All 17 map in the C-terminal half of the dnaC gene. DnaC loads the DnaB helicase onto DNA as a prelude for primosome assembly and DNA replication. We conclude that priA's primosome-assembly activity is essential for DNA repair and recombination and that the dnaC suppressor mutations allow these processes to occur in the absence of priA.

scholarly journals dnaC mutations suppress defects in DNA replication- and recombination-associated functions in priB and priC double mutants in Escherichia coli K-12

1999 ◽  
Vol 34 (1) ◽  
pp. 91-101 ◽  
Author(s):  
Steven J. Sandler ◽  
Kenneth J. Marians ◽  
Kenton H. Zavitz ◽  
Jaime Coutu ◽  
Michelle A. Parent ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Dna Replication ◽  
Associated Functions ◽  
K 12

scholarly journals Mode of initiation of constitutive stable DNA replication in RNase H-defective mutants of Escherichia coli K-12.

1987 ◽  
Vol 169 (6) ◽  
pp. 2650-2658 ◽  
Author(s):  
K von Meyenburg ◽  
E Boye ◽  
K Skarstad ◽  
L Koppes ◽  
T Kogoma
Keyword(s):  
Escherichia Coli ◽  
Dna Replication ◽  
Rnase H ◽  
Stable Dna Replication ◽  
K 12

scholarly journals Multiple Genetic Pathways for Restarting DNA Replication Forks in Escherichia coli K-12

Genetics ◽  
2000 ◽  
Vol 155 (2) ◽  
pp. 487-497
Author(s):  
Steven J Sandler
Keyword(s):  
Escherichia Coli ◽  
Dna Replication ◽  
Double Mutant ◽  
Synthetic Lethality ◽  
Replication Forks ◽  
Viability Assay ◽  
Replication Restart ◽  
K 12 ◽  
Redundant Functions

Abstract In Escherichia coli, the primosome assembly proteins, PriA, PriB, PriC, DnaT, DnaC, DnaB, and DnaG, are thought to help to restart DNA replication forks at recombinational intermediates. Redundant functions between priB and priC and synthetic lethality between priA2::kan and rep3 mutations raise the possibility that there may be multiple pathways for restarting replication forks in vivo. Herein, it is shown that priA2::kan causes synthetic lethality when placed in combination with either Δrep::kan or priC303:kan. These determinations were made using a nonselective P1 transduction-based viability assay. Two different priA2::kan suppressors (both dnaC alleles) were tested for their ability to rescue the priA-priC and priA-rep double mutant lethality. Only dnaC809,820 (and not dnaC809) could rescue the lethality in each case. Additionally, it was shown that the absence of the 3′-5′ helicase activity of both PriA and Rep is not the critical missing function that causes the synthetic lethality in the rep-priA double mutant. One model proposes that replication restart at recombinational intermediates occurs by both PriA-dependent and PriA-independent pathways. The PriA-dependent pathways require at least priA and priB or priC, and the PriA-independent pathway requires at least priC and rep. It is further hypothesized that the dnaC809 suppression of priA2::kan requires priC and rep, whereas dnaC809,820 suppression of priA2::kan does not.

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