Nucleotide Sequence of the Bacillus licheniformis Homologue of the Sporulation Locus spoIIA of Bacillus subtilis

Abstract

The spoIIA locus of Bacillus licheniformis was cloned into the phage vector phi 105J9; selection was based on the ability of the clone to complement mutations in both the first and the last of the spoIIA genes of B. subtilis. The B. licheniformis DNA was subcloned into M13 and sequenced; it includes three genes of identical lengths to those of B. subtilis. The average interspecies difference in nucleotide sequence is 24%; C occurs at the third position of codons 55% more often in the B. licheniformis than in the B. subtilis sequence. The average difference in predicted amino acid sequence is 11%, but the distribution of these differences is far from random, and there are several long stretches of amino acid sequence that are identical in the two organisms. The distribution of non-conservative amino acid changes between the species is also strikingly non-random; no such changes are found in those regions in which missense mutations are known in B. subtilis. Each species has an open reading frame 5' of the spoIIAA gene, but the predicted amino acid sequence, and the distribution of differences between the two species in both nucleotides and predicted amino acids, suggest that these open reading frames are not expressed. Both species have regions 3' of the open reading frames which resemble rho-independent terminators of transcription, but that in B. licheniformis is longer and could form a more elaborate secondary structure than that in B. subtilis.