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Identification and characterization of the single-stranded DNA-binding protein of bacteriophage P1.

ABSTRACT: The genome of bacteriophage P1 harbors a gene coding for a 162-amino-acid protein which shows 66% amino acid sequence identity to the Escherichia coli single-stranded DNA-binding protein (SSB). The expression of the P1 gene is tightly regulated by P1 immunity proteins. It is completely repressed during lysogenic growth and only weakly expressed during lytic growth, as assayed by an ssb-P1/lacZ fusion construct. When cloned on an intermediate-copy-number plasmid, the P1 gene is able to suppress the temperature-sensitive defect of an E. coli ssb mutant, indicating that the two proteins are functionally interchangeable. Many bacteriophages and conjugative plasmids do not rely on the SSB protein provided by their host organism but code for their own SSB proteins. However, the close relationship between SSB-P1 and the SSB protein of the P1 host, E. coli, raises questions about the functional significance of the phage protein.

SUBMITTER: Lehnherr H

PROVIDER: S-EPMC103783 | biostudies-literature | 1999 Oct

REPOSITORIES: biostudies-literature

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Identification and characterization of the single-stranded DNA-binding protein of bacteriophage P1.

Lehnherr H H Bendtsen J D JD Preuss F F Ilyina T V TV

Journal of bacteriology 19991001 20

The genome of bacteriophage P1 harbors a gene coding for a 162-amino-acid protein which shows 66% amino acid sequence identity to the Escherichia coli single-stranded DNA-binding protein (SSB). The expression of the P1 gene is tightly regulated by P1 immunity proteins. It is completely repressed during lysogenic growth and only weakly expressed during lytic growth, as assayed by an ssb-P1/lacZ fusion construct. When cloned on an intermediate-copy-number plasmid, the P1 gene is able to suppress t ...[more]

PMID: 10515938

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Project description:Deinococcus radiodurans R1 is one of the most radiation-resistant organisms known and is able to repair an unusually large amount of DNA damage without induced mutation. Single-stranded DNA-binding (SSB) protein is an essential protein in all organisms and is involved in DNA replication, recombination and repair. The published genomic sequence from Deinococcus radiodurans includes a putative single-stranded DNA-binding protein gene (ssb; DR0100) requiring a translational frameshift for synthesis of a complete SSB protein. The apparently tripartite gene has inspired considerable speculation in the literature about potentially novel frameshifting or RNA editing mechanisms. Immediately upstream of the ssb gene is another gene (DR0099) given an ssb-like annotation, but left unexplored.A segment of the Deinococcus radiodurans strain R1 genome encompassing the ssb gene has been re-sequenced, and two errors involving omitted guanine nucleotides have been documented. The corrected sequence incorporates both of the open reading frames designated DR0099 and DR0100 into one contiguous ssb open reading frame (ORF). The corrected gene requires no translational frameshifts and contains two predicted oligonucleotide/oligosaccharide-binding (OB) folds. The protein has been purified and its sequence is closely related to the Thermus thermophilus and Thermus aquaticus SSB proteins. Like the Thermus SSB proteins, the SSBDr functions as a homodimer. The Deinococcus radiodurans SSB homodimer stimulates Deinococcus radiodurans RecA protein and Escherichia coli RecA protein-promoted DNA three-strand exchange reactions with at least the same efficiency as the Escherichia coli SSB homotetramer.The correct Deinococcus radiodurans ssb gene is a contiguous open reading frame that codes for the largest bacterial SSB monomer identified to date. The Deinococcus radiodurans SSB protein includes two OB folds per monomer and functions as a homodimer. The Deinococcus radiodurans SSB protein efficiently stimulates Deinococcus radiodurans RecA and also Escherichia coli RecA protein-promoted DNA strand exchange reactions. The identification and purification of Deinococcus radiodurans SSB protein not only allows for greater understanding of the SSB protein family but provides an essential yet previously missing player in the current efforts to understand the extraordinary DNA repair capacity of Deinococcus radiodurans.

Dataset Information

Identification and characterization of the single-stranded DNA-binding protein of bacteriophage P1.

Publications

Identification and characterization of the single-stranded DNA-binding protein of bacteriophage P1.

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