Sequence comparison of outer membrane phospholipases A: implications for structure and for the catalytic mechanism.

In this study, the nucleotide sequence of the Enterobacter agglomerans pldA gene encoding outer membrane phospholipase A (OMPLA; EC 3.1.1.32) was determined. Five other OMPLA amino acid sequences have previously been described, and screening of data bases of whole genome sequencing projects revealed the presence of proteins with homology to OMPLA in Helicobacter pylori, Campylobacter jejuni, Yersinia pestis, Neisseria menigitidis and Neisseria gonorrhoeae. Comparison of these eleven OMPLA amino acid sequences revealed that 30 amino acid residues are completely conserved. Implications of the sequence comparison for the catalytic mechanism of OMPLA are discussed. The presence of proteins homologous to OMPLA even in non-enterobacterial Gram-negative bacteria indicates an important physiological role of this enzyme.