Comparative modelling of LysB from the mycobacterial bacteriophage Ardmore.

Abstract

Given their potential as specific and natural biocontrol agents, bacteriophages and their associated proteins have become the focus of renewed attention over the last decade. The aim of this study was to use a comparative modelling approach to generate a predicted 3D structure for LysB; a 332 amino acid lipolytic enzyme encoded by the mycobacteriophage Ardmore. The GXSXG pentapeptide, characteristic of lipolytic enzymes, was located at amino acid position 166-170. The three absolutely conserved residues among mycobacteriophage LysB proteins were also identified in Ardmore LysB as Ser-168, Gly-203 and Pro-205. CATH analysis of Ardmore LysB revealed a mainly Beta classification, Beta Barrel architecture and a topology similar to maltoporin. This is unlike the α/β hydrolase structure reported for the D29 LysB protein and, in fact appears in only 3 other sequenced LysB homologues to date. A search for conserved motifs within the amino acid sequence of LysB revealed the presence of both a cutinase motif and a PE-PPE motif. This study presents an in silico 3D predictive model of Ardmore lysin and confirms the high diversity of mycobacteriophages LysB proteins both at the sequence (2D) and structural (predicted 3D) levels.