Secretory protein Rv1987, a ‘probable chitinase’ fromMycobacterium tuberculosisis a novel chitin and cellulose binding protein lacking enzymatic function

Bacterial chitinases serve to hydrolyse chitin as food source or as defence mechanism. Given that chitin is not produced by mammals, it is intriguing thatMycobacterium tuberculosis, an exclusively human pathogen harbours Rv1987, a probable chitinase and secretes it. Interestingly genes annotated as chitinases are widely distributed amongMycobacterium tuberculosiscomplex species, clinical isolates and other human pathogensM. abscessusandM. ulcerans. However, Mycobacterial chitinases are not characterized and hence the functions remain unknown. In the present study, we show that Rv1987 is a chitin and cellulose binding protein lacking enzymatic activity in contrary to its current annotation. Further, we show Rv1987 has moon lighting functions inM. tuberculosispathobiology signifying roles of bacterial cellulose binding clusters in infections.