Structural characterization of a novel subfamily of leucine-rich repeat proteins from the human pathogen Leptospira interrogans

Abstract

Pathogenic Leptospira spp. are the agents of leptospirosis, an emerging zoonotic disease. Analyses of Leptospira genomes have shown that the pathogenic leptospires (but not the saprophytes) possess a large number of genes encoding proteins containing leucine-rich repeat (LRR) domains. In other pathogenic bacteria, proteins with LRR domains have been shown to be involved in mediating host-cell attachment and invasion, but their functions remain unknown in Leptospira. To gain insight into the potential function of leptospiral LRR proteins, the crystal structures of four LRR proteins that represent a novel subfamily with consecutive stretches of a 23-amino-acid LRR repeat motif have been solved. The four proteins analyzed adopt the characteristic α/β-solenoid horseshoe fold. The exposed residues of the inner concave surfaces of the solenoid, which constitute a putative functional binding site, are not conserved. The various leptospiral LRR proteins could therefore recognize distinct structural motifs of different host proteins and thus serve separate and complementary functions in the physiology of these bacteria.

An extracellular Leptospira interrogans leucine‐rich repeat protein binds human E‐ and VE‐cadherins

“…Bioinformatic analyses of LRR protein sequences predicted extracellular localization for the majority of these proteins (Miras et al, ), and some of these predictions have been confirmed experimentally in a previous study quantifying Leptospira exoproteins (Eshghi et al, ). In that study, LIC10831 was characterized as enriched in the culture medium, suggesting active export.…”

“…Our previous study on the structure of several leptospiral LRR proteins suggested a similarity in structure and binding pocket of LIC10831 to InlA from L. monocytogenes (Miras et al, ), a well‐studied human epithelial cadherin (hE‐Cad)‐binding protein (Bierne et al, ; Wollert, Heinz, & Schubert, ). Due to this similarity, we decided to investigate whether LIC10831 is also capable of interacting with this host protein.…”

“…Structural characterization of rLIC10831 identified an interaction of the zinc cation with rLIC10831 (Miras et al, ), prompting us to hypothesise that zinc might alter the binding capacity of LIC10831 for hE‐Cad. In SPR experiments, inclusion of zinc increased the R max in a concentration‐dependent manner (Figure a) and reduced the K D of rLIC10831 binding to rhE‐Cad approximately threefold to 0.8 μM at the highest Zn concentration tested (500 μM).…”

DIALS: implementation and evaluation of a new integration package

“…Crystals of the leucine-rich repeat (LRR) protein from L. interrogans containing residues 30-377 were kindly provided by Ahmed Haouz (Institut Pasteur) and William Shepard (Synchrotron SOLEIL). Details of the crystal preparation have been published elsewhere (Miras et al, 2015).…”

Pathogenic <i>Leptospira</i>: Advances in understanding the molecular pathogenesis and virulence

“…Earlier investigations (Evangelista and Coburn, 2010;Chaemchuen et al, 2011;Domingos et al, 2012) and more recent studies Gomard et al, 2016;Vieira and Nascimento, 2016) have described antigens that mediate host-pathogen interactions among Leptospira species. Recent genome analyses studies indicated that the leptospira characterized as pathogenic possess a number of genes that coded for proteins containing leucine-rich repeat (LRR) domains (Nitipan et al, 2013;Miras et al, 2015), presumed to be important in structural motifs of different host proteins (Miras et al, 2015). Interestingly, these characteristics were not observed in saprophytes.…”