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SUBCELLULAR LOCALIZATION OF RICKETTSIAL INVASION PROTEIN, INVA

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  • 1 Department of Microbiology and Immunology, School of Medicine, University of Maryland, Baltimore, Maryland
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To understand further the molecular basis of rickettsial host cell invasion, Rickettsia prowazekii invasion gene homolog (invA) has been characterized. Our previous experiments have shown that InvA is an Ap5A pyrophosphatase, a member of the Nudix hydrolase family, which is up-regulated during the internalization, early growth phase, and exit steps during rickettsial mammalian cell infection. In addition to the molecular characterization, subcellular localization of InvA was investigated. InvA-specific antibodies were raised in mice and used for immunoelectron microscopy. The generated antibodies were shown to recognize InvA and by immunogold labeling showed InvA in the cytoplasm of rickettsiae. A cytoplasmic location for InvA would allow for a rapid response to any internal substance and efficient functioning in hydrolysis of toxic metabolic by-products that are accumulated in the rickettsial cytoplasm during host cell invasion. Protecting bacteria from a hazardous environment could enhance their viability and allow them to remain metabolically active, which is a necessary step for the rickettsial obligate intracellular lifestyle.

Author Notes

Reprint requests: Abdu F. Azad, Department of Microbiology and Immunology, School of Medicine, University of Maryland, 655 West Baltimore Street, Baltimore, MD 21201, Telephone: 410-706-3335, Fax: 410-706-0282, E-mail: aazad@umaryland.edu
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