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Microb Pathog. 2012 Apr;52(4):227-38. doi: 10.1016/j.micpath.2012.01.004. Epub 2012 Jan 15.

The Mycobacterium avium ESX-5 PPE protein, PPE25-MAV, interacts with an ESAT-6 family Protein, MAV_2921, and localizes to the bacterial surface.

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  • 1Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA.


Previous research has demonstrated that inactivation of the Mycobacterium avium gene, PPE25-MAV (MAV_2928), leads to a significant attenuation of virulence in both in vitro and in vivo models. PPE25-MAV encodes for a PPE family protein, a family from which many members have been implicated in both bacterial virulence and host immune recognition. Recent research has shown that many PPE family proteins are exported by a specialized Type VII secretion system in mycobacteria. In this context, the mechanisms of PPE25-MAV in M. avium pathogenesis were investigated. A mycobacterial 2-hybrid system was used to perform a directed search for M. avium proteins that interact directly with PPE25-MAV. An interaction was observed between PPE25-MAV and the ESAT-6 family protein, MAV_2921, and was further defined by 2-hybrid analysis of truncated PPE25-MAV, and confirmed by co-immunoprecipitation. Localization of the PPE25-MAV protein was analyzed in Mycobacterium smegmatis expressing the recombinant protein and a significant percentage of PPE25-MAV was shown to be exposed at the bacterial surface by surface biotinylation and trypsin protection assays. Finally, transcriptional analysis of PPE25-MAV and its associated operon suggested that nutrient limitation, a condition which occurs in the phagosome, plays a role in regulating expression of the PPE25-MAV gene.

Copyright © 2012 Elsevier Ltd. All rights reserved.

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