Mapping and Properties of the gam and sot Genes of Phage Mu: Their Possible Roles in Recombination

Akroyd, J.; Barton, Barry; Lund, Peter; Smith, Sarah; Sultana, Kazi Zakia; Symonds, N.

doi:10.1101/sqb.1984.049.01.030

Cited by 11 publications

(9 citation statements)

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“…However, we found that the Gam gene of Mu phage encodes a protein with homology to Ku. Previous work has indicated that Mu Gam facilitates Mu replication (Goosen et al ., 1982) and that Gam can bind non‐specifically to DNA and protect linear Mu phage DNA from digestion with nuclease (Akroyd et al ., 1984; Akroyd & Symonds, 1986; Abraham & Symonds, 1990). As described here, our further analysis of Gam indicates that it is indeed a functional counterpart of eukaryotic Ku.…”

Section: Introductionmentioning

confidence: 99%

The Gam protein of bacteriophage Mu is an orthologue of eukaryotic Ku

et al. 2003

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Section: Introductionmentioning

confidence: 99%

The Gam protein of bacteriophage Mu is an orthologue of eukaryotic Ku

et al. 2003

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show abstract

“…1) which contains the Mu gam gene cloned on a 1.58 kb EcoRI fragment downstream from the A promoter, controlled by the temperature sensitive Xcl857 repressor, was used to produce high levels of the gam protein for purification. The construction of pJA21 has been described previously (15). The presence of pJA21 in thermo-induced E. coli cells greatly enhances the frequency with which Mu transfects these cells, and cell-extracts have been shown to contain a potent exonuclease inhibitor, indicating that the gam and sot gene products are expressed effectively by pJA21 (15).…”

Section: Isolation Of Pgammentioning

confidence: 99%

“…The gam and sot phenotypes are both related to protection of DNA from exonuclease attack. Cloning experiments by Akroyd et al (15) suggest that the gam and sot phenotypes are both manifestations of the same polypeptide of MW approximately 20,000 encoded by one small fragment of DNA of 1.6 kb. We have previously shown that the Mu gam gene product is a non-specific DNA binding protein that interacts with linear double-stranded DNA, preventing nucleolytic breakdown (15).…”

Section: Introductionmentioning

confidence: 99%

“…Cloning experiments by Akroyd et al (15) suggest that the gam and sot phenotypes are both manifestations of the same polypeptide of MW approximately 20,000 encoded by one small fragment of DNA of 1.6 kb. We have previously shown that the Mu gam gene product is a non-specific DNA binding protein that interacts with linear double-stranded DNA, preventing nucleolytic breakdown (15). In addition to stimulating transfection with linear Mu DNA, over-production of the gai and sot gene products in a recipient bacterium also stimulates the transformation frequency of a variety of linear plasmid DNA's (15).…”

Section: Introductionmentioning

confidence: 99%

“…We have previously shown that the Mu gam gene product is a non-specific DNA binding protein that interacts with linear double-stranded DNA, preventing nucleolytic breakdown (15). In addition to stimulating transfection with linear Mu DNA, over-production of the gai and sot gene products in a recipient bacterium also stimulates the transformation frequency of a variety of linear plasmid DNA's (15). Delayed lysis and elevated lysogenization frequencies are exhibited by gam-deficient viruses, indicating the significance of pgaim in phage development and transposition (15).…”

Section: Introductionmentioning

confidence: 99%

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Purification of thegamgene-product of bacteriophage Mu and determination of the nucleotide sequence of thegamgene

Akroyd¹,

Clayson

Higgins

1986

Nucl Acids Res

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The gam gene of bacteriophage Mu encodes a protein which protects linear double stranded DNA from exonuclease degradation in vitro and in vivo. We purified the Mu gam gene product to apparent homogeneity from cells in which it is over-produced from a plasmid clone. The purified protein is a dimer of identical subunits of 18.9 kd. It can aggregate DNA into large, rapidly sedimenting complexes and is a potent exonuclease inhibitor when bound to DNA. The N-terminal amino acid sequence of the purified protein was determined by automated degradation and the nucleotide sequence of the Mu gam gene is presented to accurately map its position in the Mu genome.

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Evidence that the normal route of replication-allowed Red-mediated recombination involves double-chain ends.

Thaler

Stahl

1987

The EMBO Journal

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Recombination mediated by the Red pathway of bacteriophage lambda is focused towards sites of double‐chain cuts. Double‐chain ends created either by type II restriction enzymes acting at unmodified recognition sites or by lambda's packaging enzyme, terminase, acting at cos are utilized in a manner similar to the double‐chain break repair pathway of recombination in yeast. When lambda is allowed to recombine during replicative growth, spontaneous recombination is approximately evenly distributed along the chromosome. It has been proposed that replication‐allowed recombination also is initiated by double‐chain ends. In order to test this hypothesis we ask if the in vivo expression of the Mu gam protein is inhibitory to Red recombination. Mu gam has been shown in vitro to bind to linearized duplex DNA and to shield bound DNA from exonucleases. The expression of Mu gam is found to be inhibitory to Red recombination whether replication is blocked or allowed. As a control we ask if Mu gam inhibits Int‐mediated recombination. It has been well documented that the Int pathway of recombination does not involve any double‐chain breaks and, consistent with this, the Int pathway is not inhibited by Mu gam. We suggest that the in vivo expression of Mu gam or other similar activities may be a generally useful way to determine if those processes that respond to an artificially introduced double‐chain cut normally involve double‐chain ends.

show abstract

Mapping and Properties of the gam and sot Genes of Phage Mu: Their Possible Roles in Recombination

Cited by 11 publications

References 0 publications

The Gam protein of bacteriophage Mu is an orthologue of eukaryotic Ku

The Gam protein of bacteriophage Mu is an orthologue of eukaryotic Ku

Purification of thegamgene-product of bacteriophage Mu and determination of the nucleotide sequence of thegamgene

Evidence that the normal route of replication-allowed Red-mediated recombination involves double-chain ends.

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