Induction of mycobacterial proteins during phagocytosis and heat shock: a time interval analysis

Abstract: Mycobacterium tuberculosis survives macro-phage bactericidal activities by mechanisms that may in-dude induction of stress proteins. We sought to determine whether the synthesis of any mycobacterial proteins is in-creased during phagocytosis and whether any of these proteins are also up-regulated during heat shock. Protein synthesis by M. tuberculosis H37Ra during phagocytosis by the mouse macrophage cell line IC-21, and during heat shock at 45 and 48#{176}C, was monitored at various time in-tervals using 35S-labeled methionine/cysteine and so-dium dodecyl sulfate-polyacrylamide gel electrophoresis. Our data suggest the existence of certain common dc-ments in the stress response of mycobacteria to the three stress stimuli. This apparent similarity was best charac-terized by the up-regulation of a 25-kDa protein after cx-posure to each of the stress conditions. Furthermore, this 25-kDa protein and a 37-kDa protein that was also syn-thesized during phagocytosis appeared to be extracellular because they were preferentially solubilized when in-fected macrophages were lysed with 0.5 % NP-40.J. Leu