This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Rahman, M. S.
Right arrow Articles by Azad, A. F.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Rahman, M. S.
Right arrow Articles by Azad, A. F.

 Previous Article  |  Next Article 

Journal of Bacteriology, January 2007, p. 336-341, Vol. 189, No. 2
0021-9193/07/$08.00+0     doi:10.1128/JB.01397-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

The lspA Gene, Encoding the Type II Signal Peptidase of Rickettsia typhi: Transcriptional and Functional Analysis{triangledown}

M. Sayeedur Rahman,* Shane M. Ceraul, Sheila M. Dreher-Lesnick, Magda S. Beier, and Abdu F. Azad

Department of Microbiology and Immunology, University of Maryland School of Medicine, 660 West Redwood Street, Baltimore, Maryland 21201

Received 31 August 2006/ Accepted 27 October 2006

Lipoprotein processing by the type II signal peptidase (SPase II) is known to be critical for intracellular growth and virulence for many bacteria, but its role in rickettsiae is unknown. Here, we describe the analysis of lspA, encoding a putative SPase II, an essential component of lipoprotein processing in gram-negative bacteria, from Rickettsia typhi. Alignment of deduced amino acid sequences shows the presence of highly conserved residues and domains that are essential for SPase II activity in lipoprotein processing. The transcription of lspA, lgt (encoding prolipoprotein transferase), and lepB (encoding type I signal peptidase), monitored by real-time quantitative reverse transcription-PCR, reveals a differential expression pattern during various stages of rickettsial intracellular growth. The higher transcriptional level of all three genes at the preinfection time point indicates that only live and metabolically active rickettsiae are capable of infection and inducing host cell phagocytosis. lspA and lgt, which are involved in lipoprotein processing, show similar levels of expression. However, lepB, which is involved in nonlipoprotein secretion, shows a higher level of expression, suggesting that LepB is the major signal peptidase for protein secretion and supporting our in silico prediction that out of 89 secretory proteins, only 14 are lipoproteins. Overexpression of R. typhi lspA in Escherichia coli confers increased globomycin resistance, indicating its function as SPase II. In genetic complementation, recombinant lspA from R. typhi significantly restores the growth of temperature-sensitive E. coli Y815 at the nonpermissive temperature, supporting its biological activity as SPase II in prolipoprotein processing.

* Corresponding author. Mailing address: Department of Microbiology and Immunology, University of Maryland School of Medicine, 660 West Redwood Street, Room HH 324, Baltimore, MD 21201. Phone: (410) 706-3337. Fax: (410) 706-0282. E-mail: mrahm001{at}umaryland.edu.

{triangledown} Published ahead of print on 10 November 2006.

Journal of Bacteriology, January 2007, p. 336-341, Vol. 189, No. 2
0021-9193/07/$08.00+0     doi:10.1128/JB.01397-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Ammerman, N. C., Rahman, M. S., Azad, A. F. (2008). Characterization of Sec-Translocon-Dependent Extracytoplasmic Proteins of Rickettsia typhi. J. Bacteriol. 190: 6234-6242 [Abstract] [Full Text]  
  • Huang, H., Lin, M., Wang, X., Kikuchi, T., Mottaz, H., Norbeck, A., Rikihisa, Y. (2008). Proteomic Analysis of and Immune Responses to Ehrlichia chaffeensis Lipoproteins. Infect. Immun. 76: 3405-3414 [Abstract] [Full Text]  


Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»