Use of phage display technology to identify proteins that interact with LipL32, the major outer membrane protein of pathogenic Leptospira

Abstract

Leptospirosis is one of the most common zoonotic diseases worldwide. The causative agent of leptospirosis is pathogenic spirochetal bacteria named Leptospira interrogans. Leptospirosis presents broad spectrum of clinical features. However, pathogenesis remains unclear. The initial step of infection requires host-pathogen interaction. Outer membrane components including outer membrane proteins (OMPs) may play a key role in host-microbe interactions. LipL32 is the major OMP that is conserved among pathogenic leptospires, constitutively expressed, immunogenic, and capable of binding to extracellular matrix of mammalian cell. To identify the host proteins that interact with LipL32, phage display technology was employed in our study. Recombinant LipL32 was produced and used as a target molecule for biopanning with random heptapeptide phage library (Ph.D.-7). Then, 52 randomly selected plaques from the third round of panning were sequenced. The result showed 6 peptide sequence patterns. The most frequent peptide sequence is WHWTYYW. From database search, putative proteins that potentially bind to LipL32 include scavenger receptor class F, chloride channel assembly 2, laminin α-5, coronin 2A, proataglandin E receptor 1 and glycoprotein VI. However, the interactions of LipL32 with these host proteins and their roles in the pathogenesis of leptospirosis require further investigation.