Structural and functional characterization of the chitin binding domain from the human macrophage chitotriosidase

Chitin is an important structural component of cell walls and exoskeletons of numerous organisms. Chitin binding proteins are closely related to those structures. They are associated to chitin stability, remodelling, recognition, metabolism and tens of biological functions. ChBD, the chitin binding domain of the human chitotriosidase (HCHT) attracted our attention due to a considerable lack of information regarding this domain. Based on literature, CBMs are known to influence significantly the behaviour of their cognate catalytic domains. We wanted to verify if it was the case for ChBD and to determine in which manner this phenomenon could occur. We investigated the biochemical function of ChBD by chitin binding studies. We analysed the structure of the CBM and defined a binding mechanism in accordance to previous publications and our experimental data. A phylogenetic analysis was used to determine the evolution path of HCHT and its constitutive domains. Altogether, our results make the link between chitin, innate immunity, ChBD and HTCH appearance.Caractérisation structurale et fonctionnelle du domaine de fixation à la chitine de la chitotriosidase de macrophage humai