Viability and preliminary in vivo characterization of site directed mutants of Escherichia coli single‐stranded DNA‐binding protein

Site‐directed mutations involving selected amino acids of Escherichia coli single‐stranded DNA‐binding protein (SSB) were tested for their in vivo functionality when introduced into a chromosomal ssb deletion strain on a plasmid. All mutants complemented the ssb deletion for viability when present on a pSC101 derivative. The generation time with ssbW54S doubled in comparison to the ssb* control, and both the ssbW54S‐ and ssbH55K‐containing strains exhibited temperature sensitivity. ssbH55K, ssbW54S, ssbW88T, and ssbH55Y ssb‐1 strains displayed reduced survival to ultraviolet irradiation, while ssbW40T and ssbF60L strains were comparable to the ssb⁺ control strain. This study represents the first investigation of the in vivo properties of ssb mutations constructed for in vitro analysis of DNA binding by SSB.