Genetic mapping of the Escherichia coli gene for the stringent starvation protein and its dispensability for normal cell growth.

To determine its map position, the sSP gene was cloned into plasmid pBR322 and the recombinant plasmid was integrated into the chromosome of a polA mutant at the site of the sSP gene by homologous recombination. The chromosomal location of Ampr was then determined by P1 phage-mediated transduction. Thus, the sSP gene was mapped between gltB and glnF at min 69.5 on the Escherichia coli chromosome. Strains were constructed in which the sSP gene was brought under the control of the lac regulatory system. This indicated that the stringent starvation protein (SSP) is dispensable for growth, at least under normal culture conditions.