PA3092 is an Escherichia coli mutant that forms filaments at 43°C in the presence of cyclic AMP (cAMP). The mutation responsible for this phenotype is called fic-l We cloned fic-l from PA3092 by selection for the neighboring argD gene. Thefic-1 gene product had a relative molecular mass of 21 kilodaltons by the maxicell method. A strain with the fic gene completely deleted was constructed by replacing fic with a kanamycin resistance gene. In one of thefic-deleted strains derived from PA3092, cAMP did not induce cell filamentation at 43°C, but it did in the same strain harboring a plasmid containing thefic-1 gene. These results indicate that thefic-l gene product is necessary for the induction of cell filamentation by cAMP but is dispensable to the cell. We also found that high levels of NaCl suppressed the cell filamentation induced by cAMP.

No abstract