F sex factor of Escherichia coli K-12 codes for a single-stranded DNA binding protein.
In Escherichia coli K-12 strains that carry the mutation ssb-1 in the gene for single-stranded DNA binding protein, the presence of the F sex factor partially reverses the temperature-sensitive growth phenotype caused by the mutation. The region of F (EcoRI fragment 3) responsible for this compensation has been identified and subcloned onto pBR322. A BamHI cleavage site has been found to intersect the essential coding region for this F function. By using this site, mutational blocks in the function have been constructed and used to identify a protein product (Mr approximately 22,000, slightly larger than the E. coli K-12 single-stranded DNA binding protein) which is correlated with the ssb-1-complementing activity. Labeled extracts from maxicells were used to show that this protein binds tightly to single-stranded DNA. The gene on F that codes for this protein is denoted ssf and is located at approximately 55.2 kilobases on the standard map of F, in the region transferred very early during bacterial conjugation.
D002352:Carrier Proteins / Q000235:genetics*; D004262:DNA Restriction Enzymes; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development; D005144:F Factor; D005838:Genotype; D010957:Plasmids; D013045:Species Specificity; D013696:Temperature
D002352:Carrier Proteins; D004262:DNA Restriction Enzymes