Structural basis of capsule biosynthesis polymerization in the human pathogenic bacteria Enterococcus faecium

Capsule polysaccharides (CPS) and wall teichoic acid (WTA) are the most important surface glycans in Gram-negative and Gram-positive bacteria, essential for survival during host colonization. CPS present a wide variety of antigens key for the development of glycoconjugate vaccines against pathogenic bacteria. On the other hand, WTA are the most abundant cell wall element in bacteria and are defined by the presence of glycerol- or ribitol-phosphate, expressed by antimicrobial-resistant ESKAPE pathogens such as Enterococcus faecium. Our group described that E. faecium serotypes synthesize different polymers on their cell wall which, in turn, depicts a chance of developing new specific vaccines against the pathogen. Cps8D is the first WTA type II capsule polymerase identified in Gram-positive bacteria and its molecular mechanism for polymer synthesis remains unclear. The present research aims at the structural study of the Enterococcus faecium LCT-EF90 capsule polymerase Cps8D.