Trichophyton rubrum LysM proteins bind to fungal cell wall chitin and to the N-linked oligosaccharides present on human skin glycoproteins

The Trichophyton rubrum genome contains six proteins containing two or more lysin M (LysM) domains. We have characterized two of these proteins, LysM1 and LysM2, and demonstrated that these proteins have the capacity to bind two substrates, chitin and N-linked oligosaccharides associated with human skin glycoproteins. We have characterized the individual LysM domains in LysM1, and shown that the protein contains two functional LysM domains. Each of these domains can bind to chitin, to N-linked oligosaccharides in human skin glycoproteins, and to N-linked oligosaccharides on fungal glycoproteins. We hypothesize that LysM proteins could provide the pathogen with three important functions. First, the T. rubrum LysM proteins could shield host cell wall chitin from the human immune system. Second, the LysM proteins could shield the pathogen’s glycoproteins from host degradation and immune surveillance. Third, the LysM proteins could help facilitate pathogen adhesion to human skin.