Mycobacterial glycoproteins: a novel subset of vaccine candidates

Over the last two decades significant research efforts and resources have been devoted to identifying mycobacterial proteins of value to diagnostic assays and vaccine formulations. These scientific endeavors were often preceded by first identifying a target population of proteins, for example cytoplasmic, cell envelope, or extracellular. However, many of these endeavors have overlooked the posttranslational modifications (PTM) to which these protein subsets may be targets of. Consequently, we may be missing essential molecular information relevant to the function and antigenicity of these effector molecules, and in turn the pathobiology of these bugs. Moreover, heterologous expression of mycobacterial proteins in hosts lacking homologous PTM systems negates any functional and/or antigenic role the PTM may impart. Functional and pathogenic roles of PTMs, such as protein glycosylation, have been reported for other Gram-positive bacteria, especially in reference to mucosal pathogens (reviewed by Szymanski and Wren, 2005). Our objective in this piece is to shed light on the lack of PTM studies so that current and future researchers hunting for diagnostic and vaccine candidates shall: (i) be made aware of PTMs of mycobacterial proteins, and (ii) come to understand their growing importance to both pathobiology and