This Article Full Text Full Text (PDF) Supplemental material Other Versions of this Article: JB.01261-06v1 189/3/844    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Kitada, S. Articles by Ito, A. Search for Related Content PubMed PubMed Citation Articles by Kitada, S. Articles by Ito, A.

 Previous Article  |  Next Article 

Journal of Bacteriology, February 2007, p. 844-850, Vol. 189, No. 3
0021-9193/07/$08.00+0     doi:10.1128/JB.01261-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

A Protein from a Parasitic Microorganism, Rickettsia prowazekii, Can Cleave the Signal Sequences of Proteins Targeting Mitochondria ^,

Department of Chemistry, Faculty of Science, Kyushu University, Fukuoka 812-8581, Japan,¹ Department of Virology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima 770-8503, Japan²

Received 10 August 2006/ Accepted 19 November 2006

The obligate intracellular parasitic bacteria rickettsiae are more closely related to mitochondria than any other microbes investigated to date. A rickettsial putative peptidase (RPP) was found to resemble the and ß subunits of mitochondrial processing peptidase (MPP), which cleaves the transport signal sequences of mitochondrial preproteins. RPP showed completely conserved zinc-binding and catalytic residues compared with ß-MPP but barely contained any of the glycine-rich loop region characteristic of -MPP. When the biochemical activity of RPP purified from a recombinant source was analyzed, RPP specifically hydrolyzed basic peptides and presequence peptides with frequent cleavage at their MPP-processing sites. Moreover, RPP appeared to activate yeast ß-MPP so that it processed preproteins with shorter presequences. Thus, RPP behaves as a bifunctional protein that could act as a basic peptide peptidase and a somewhat regulatory protein for other protein activities in rickettsiae. These are the first biological and enzymological studies to report that a protein from a parasitic microorganism can cleave the signal sequences of proteins targeted to mitochondria.

Published ahead of print on 8 December 2006.

Supplemental material for this article may be found at http://jb.asm.org/.