Suppression of tif-mediated induction of SOS functions in Escherichia coli by an altered dnaB protein

D’Ari, Richard; George, Jacqueline; Huisman, Olivier

doi:10.1128/jb.140.2.381-387.1979

Cited by 18 publications

(5 citation statements)

References 21 publications

(29 reference statements)

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“…These proteins may be able to bind the transient ssDNA in an undamaged cell, such as at replication forks. In support of this, the coprotease activity of RecA441 protein can be suppressed by the dnaB252 mutation, in which initiation of replication is inhibited, thereby eliminating replication forks and hence the available ssDNA (45). As is seen with RecA441 and RecA730 proteins, the data in this study suggest that the constitutive coprotease activity of RecA P67W protein can be credited to an enhanced ability to displace SSB protein.…”

Section: Discussionsupporting

confidence: 66%

Biochemical Basis of the Constitutive Coprotease Activity of RecA P67W Protein

Mirshad

Kowalczykowski

2003

Biochemistry

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The mutation of Pro67 to Trp (P67W) in the Escherichia coli RecA protein results in reduced recombination and constitutive coprotease phenotypes. We examined the biochemical properties of this mutant in an effort to understand these altered behaviors. We find that RecA P67W protein can access single-stranded DNA (ssDNA) binding sites within regions of secondary structure more effectively than wild-type protein, and binding to duplex DNA is both faster and more extensive as well. This mutant is also more effective than wild-type RecA protein in displacing SSB protein from ssDNA. An enhancement in SSB protein displacement has been shown previously for RecA441, RecA730, and RecA803 proteins, and similarly, this improved ability to displace SSB protein for RecA P67W protein correlates with an increased rate of association with ssDNA. As for the aforementioned mutant RecA proteins, we expect that this enhanced activity will allow RecA P67W protein to bind ssDNA naturally occurring in undamaged cells and to constitutively induce the SOS response. The DNA strand exchange activity of RecA P67W protein is also altered. Although the rate of duplex DNA uptake into joint molecules is increased compared to that of wild-type RecA protein, the resolution to the nicked circular dsDNA product is reduced. We suggest that either a limited amount of DNA strand reinvasion or a defect in DNA heteroduplex extension is responsible for the impaired recombination ability of this mutant protein.

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Section: Discussionsupporting

confidence: 66%

Biochemical Basis of the Constitutive Coprotease Activity of RecA P67W Protein

Mirshad

Kowalczykowski

2003

Biochemistry

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“…Bagdasarian et al (2) postulated that R100 may code for a dnaB analog capable of interfer-ing with activation of tif-J protein. The dnaB252 mutation has a similar effect on tif-J (8). In the case of R100, interference with tif-l activation was independent of the drd-l mutation, whereas in our case, dnaB analog gene expression was dependent upon drd-1.…”

Section: 6supporting

confidence: 44%

dnaB analog function associated with plasmid R100drd-1

Potter¹,

Iyer²

1983

J Bacteriol

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Plasmid R100 and a number of its derivatives were able to suppress the temperature sensitivity of strains carrying different alleles of the dnaB gene of Escherichia coli K-12. R1O0drd-J and pAR132 were able to rescue a strain carrying the dnaB266(Am) mutation in the absence of any known amber suppressors. This was taken as evidence for the existence of an R1OOdrd-J dnaB analog function. The R1OOdrd-J dnaB analog was different from those of bacteriophages P1 and P7 in that it was able to support the growth of bacteriophage lambda in a dnaB266(Am) background. The dnaB analog was also shown to be thermosensitive. The structural gene for this protein lies within the EcoRI fragment D of R1OOdrd-1.

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“…It has been suggested that the RecA441 protein becomes activated by binding to regions of singlestranded DNA such as those at the replicating fork that are found in uninduced cells (282). The observation that the initiation-defective dnaB252 allele suppresses RecA441-mediated induction raises the possibility that the RecA protein might be directly involved in the replication complex in processes leading to its activation (65).…”

Section: Walkermentioning

confidence: 99%