Identification of host surface proteins that interact with lipl32, the major outer membrane protein of pathogenic leptospira

Abstract

Leptospirosis is a zoonotic disease that causes public health problems worldwide. Pathogenic Leptospira interrogans is a causative agent of leptospirosis. However, pathogenesis of leptospirosis remains unclear. Surface-exposed outer membrane proteins (OMPs) are important for initial step of interactions between pathogenic Leptospira and host cells. LipL32 is the most abundant surface-exposed protein of pathogenic Leptospira, is highly conserved in all pathogenic leptospires but is absent in non-pathogenic Leptospira. It is expressed at high level in leptospires during acute lethal infection and is highly immunogenic. This study aimed to identify host proteins that interact with LipL32. Using far western blot, peroxiredoxin was identified by liquid chromatography–mass spectrometry as a putative protein that interacts with LipL32. In addition, phage display screening was performed by using recombinant LipL32 as a target molecule for biopanning with T7 select® cDNA liver phage display library. Phages with the hightest affinity to LipL32 displayed protein sequence that matched ATPsynthase. However, bacterial pull-down assay was unsuccessful to identify specific host proteins that bound to wild-type Leptospira but not to lipL32- mutants. Therefore, binding of LipL32 to peroxiredoxin and ATPsynthase may play a role in pathogenesis of leptospirosis. However, further studies are required to confirm true interactions between these proteins and LipL32.