Secretome differences between the taxonomically related but clinically differing mycobacterial species Mycobacterium abscessus and M. chelonae

DOI: 10.5584/jiomics.v2i2.98

Abstract

Rapidly growing non-tuberculous mycobacteria (NTM) are significant human pathogens which show high inter-species differences in clinical characteristics (virulence, host immune response) during infection even within a given NTM complex. Understanding the differences between the secreted proteomes of the member species for an NTM complex may reveal the basis of their differential virulence and host pathogenesis potential including host immune reactions.  In this study, major secreted proteins of the two taxonomically close but clinically differing member species M. abscessus and M. chelonae of the M. chelonae-M. abscessus(MCA) complex were compared using an approach based on 2-dimensional gel electrophoresis (2-DE) and MALDI-TOF analyses. The two secretomes showed dramatic differences. Of the 73 major secreted proteins identified, majority were expressed in a species-specific manner, including 37 in M. chelonae and 32 in M. abscessus. Interestingly, 9 of these differentially expressed proteins were orphan proteins showing homology to either hypothetical proteins or those with no defined function. The other 60 distinctly expressed proteins were homologs of those associated with various bacterial cellular functions and virulence, namely cell wall synthesis or lipid metabolism, metabolic and respiratory pathways, stress response and signal transduction, gene regulation, and immune response. This information on species-specific secreted proteins would help understand the critical virulence factors and host pathogenesis mechanisms in these mycobacterial species and provide the basis for developing better therapeutic strategies. These proteins may also serve as potential targets for species-specific diagnosis as an additional outcome. To our knowledge, this is the first attempt to characterize the secretome of M. chelonae (for which the genome sequence is not yet available) and the secretome differences between M. abscessus and M. chelonae