EXCHANGE OF PRECURSOR-SPECIFIC ELEMENTS BETWEEN PRO-SIGMA(E) AND PRO-SIGMA(K) OF BACILLUS-SUBTILIS

sigma(E) and sigma(K) are sporulation-specific sigma factors of Bacill us subtilis that are synthesized as inactive proproteins. Pro-sigma(E) and pro-sigma(K) are activated by the removal of 27 and 20 amino acid s, respectively, from their amino termini. To explore the properties o f the precursor-specific sequences, we exchanged the coding elements f or these domains in the sigma(E) and sigma(K) structural genes and det ermined the properties of the resulting chimeric proteins in B. subtil is. The pro-sigma(E)-sigma(K) chimera accumulated and was cleaved into active sigma(K), while the pro-sigma(K)-sigma(E) fusion protein faile d to accumulate and is likely unstable in B. subtilis. A fusion of the sigE ''pro'' sequence to an unrelated protein (bovine rhodanese) also formed a protein that was cleaved by the pro-sigma(E) processing appa ratus. The data suggest that the sigma(E) pro sequence contains suffic ient information for pro-sigma(E) processing as well as a unique quali ty needed for sigma(E) accumulation.