Interaction of human mannose-binding lectin (MBL) with Yersinia enterocolitica lipopolysaccharide

Abstract

tThe lipopolysaccharide (LPS) is involved in the interaction between Gram-negative pathogenic bacteriaand host. Mannose-binding lectin (MBL), complement-activating soluble pattern-recognition receptortargets microbial glycoconjugates, including LPS. We studied its interactions with a set of Yersinia ente-rocolitica O:3 LPS mutants. The wild-type strain LPS consists of lipid A (LA) substituted with an inner coreoligosaccharide (IC) which in turn is substituted either with the O-specific polysaccharide (OPS) or theouter core hexasaccharide (OC), and sometimes also with the enterobacterial common antigen (ECA). TheLPS mutants produced truncated LPS, missing OPS, OC or both, or, in addition, different IC constituentsor ECA. MBL bound to LA-IC, LA-IC-OPS and LA-IC-ECA but not LA-IC-OC structures. Moreover, LA-IC sub-stitution with both OPS and ECA prevented the lectin binding. Sequential truncation of the IC heptosesdemonstrated that the MBL targets the IC heptose region. Furthermore, microbial growth temperatureinfluenced MBL binding; binding was stronger to bacteria grown at room temperature (22◦C) than to bac-teria grown at 37◦C. In conclusion, our results demonstrate that MBL can interact with Y. enterocoliticaLPS, however, the in vivo significance of that interaction remains to be elucidated.