Sunday, August 10, 2008
P61

The Effect of Cobalt on Cell Envelope Components of Rhodococcus sp DAP 96253

Trudy M. Tucker1, Sidney A. Crow1, and George E. Pierce2. (1) Biology, Georgia State University, 24 Peachtree Center Avenue, 402 Kell Hall, Atlanta, GA 30341, (2) Department of Biology, Georgia State University, 24 Peachtree Center Ave, Atlanta, GA 30303

 Rhodococcus sp. possess a unique cell envelope composed of mycolic acids. Rhodococcus sp. DAP 96253 is capable of transforming nitriles to their corresponding amides through the enzyme Nitrile Hydratase (NHase). NHase from Rhodococcus DAP 96253 is a soluble cobalt-serine protease, that is significantly induced by the presence of cobalt in growth media.The purpose of this study was to investigate the effect of cobalt on certain cell envelope components such as mycolic acids and proteins.

 Changes in mycolic acids were investigated by examining HPLC profiles. Antibiotic susceptibility tests (measuring zones of inhibition for vancomycin) and proteomic studies were also conducted.

Components of the rhodococcal cell envelope such as mycolic acids proteins and were affected by addition of cobalt in growth media of Rhodococcus. The supplementation of cobalt in growth media resulted in significant changes in the mycolic profiles, with a 200% increase in mycolic acids content. Antibiotic susceptibility tests with Rhodococcus sp. DAP 96253 showed that the presence of cobalt, in the growth media resulted in a three-fold increase in antibiotic sensitivity to vancomycin. Proteomic studies showed that supplementation of cobalt resulted in increased levels of outer membrane protein found in metal transport and other proteins involved mycolic acid synthesis.

This work showed that cobalt not only impacts NHase activity but also mycolic acid synthesis, and transport of other compounds into the cell.


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