Identification and biochemical analysis of a novel pectate lyase 3 gene in Bursaphelenchus xylophilus

A novel pectate lyase 3 (Bx-PEL3) gene from the stage-specifically expressed sequence tag library of Bursaphelenchus xylophilus was cloned. Bx-PEL1 and Bx-PEL2 were relatively predominant to Bx-PEL3 in quantitative real-time PCR analysis. The variation of expression level among Bx-PELs according to different life stages suggests that each Bx-PEL may play different biochemical roles in pathogenesis. Recombinant Bx-PEL3 showed activity against polygalacturonic acid and its optimized physical conditions for pH and Ca2+ concentrations were 9.0 and 0.5 mM, respectively. Homology modeling revealed that Bx-PELs were structurally similar to PEL from the Bacillus strain KSM P-15 and shared essential residues for calcium binding and catalytic activity. Bx-PEL3 was expressed near the esophageal gland as shown in other Bx-PELs, indicating that Bx-PEL3 may be involved in the degradation of the cell wall after secretion from the stylet. Our data suggest that the novel PEL3 gene is a putative pathogenic factor which is biochemically functional. (C) Korean Society of Applied Entomology, Taiwan Entomological Society and Malaysian Plant Protection Society, 2013. Published by Elsevier B.V. All rights reserved.