TOXIC PHOSPHOLIPASES-D OF CORYNEBACTERIUM-PSEUDOTUBERCULOSIS, C-ULCERANS AND ARCANOBACTERIUM-HAEMOLYTICUM - CLONING AND SEQUENCE HOMOLOGY

The genes encoding toxic phospholipases D (PLD) from Corynebacterium p seudotuberculosis (Cp)biovar equi and C. ulcerans (Cu) have been clone d and sequenced. The deduced proteins are 307 amino acids (aa) in leng th and include a putative signal sequences of 26-aa. A molecular mass of 31.2 and 31.0 kDa and pi values of 8.84 and 6.73 are predicted for the secreted (mature) proteins from Cp and Cu, respectively. Compariso n of the deduced primary structure of the two proteins to those of the PLD produced by Cp biovar ovis and Arcanobacterium haemolyticum (Ah) revealed that the four enzymes share 64-97% identity. The aa sequences of this group of proteins were unique when compared to the sequences of other phospholipases in GenBank and were found to share only small regions of homology with other proteins, including two conserved domai ns of glyceraldehyde-3-phosphate dehydrogenase (G3PD). The similarity of PLD from Cp biovar equi, Cu and Ah to the PLD of Cp biovar ovis sug gests that these enzymes may act as virulence determinants.