Skip Navigation



MBE Advance Access published online on December 1, 2004
Molecular Biology and Evolution, doi:10.1093/molbev/msi061
Molecular Biology and Evolution © Society for Molecular Biology and Evolution 2004; all rights reserved
This Article
Right arrow Advance Access manuscript (PDF) Freely available
Right arrow Correction to PDF
Right arrow All Versions of this Article:
22/3/758    most recent
msi061v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
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 Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Dale, C.
Right arrow Articles by Pontes, M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Dale, C.
Right arrow Articles by Pontes, M.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

Accepted November 25, 2004

Research Article

Degenerative Evolution and Functional Diversification of Type-III Secretion Systems in the Insect Endosymbiont Sodalis glossinidius

Colin Dale 1*, Tait Jones 1, and Mauricio Pontes 1

1 Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, UT, 84112

* To whom correspondence should be addressed.
Colin Dale, E-mail: dale{at}biology.utah.edu


  Abstract

Sodalis glossinidius, a maternally transmitted endosymbiont of tsetse flies, maintains two phylogenetically distinct type-III secretion systems encoded by chromosomal symbiosis regions designated SSR-1 and SSR-2. Although both symbiosis regions are closely related to extant pathogenicity islands with similar gene inventories, SSR-2 has undergone novel degenerative adaptations in the transition to mutualism. Notably, SSR- 2 lacks homologs of genes found in SSR-1 that encode secreted effector proteins known to facilitate the host cell cytoskeletal rearrangements necessary for bacterial entry and uptake into eukaryotic cells. Also, as a result of relaxed selection, SSR-2 has undergone inactivation of genes encoding components of the type-III secretion system needle substructure. In the current study, we used quantitative PCR to determine the expression profiles of ysaV (SSR-1) and invA (SSR-2) transcripts when S. glossinidius infects an insect cell line, and we used an invasion assay to characterize the phenotype of a S. glossinidius mutant that lacks the ability to produce an OrgA protein that is required for function of the SSR-2 secretome. Whereas SSR-1 is required for bacterial invasion of host cells and ysaV is expressed when bacteria contact host cells, SSR-2 is required for bacterial proliferation following entry and invA is only expressed in the intracellular stage of infection. These results demonstrate that degenerative genetic adaptations in SSR-2 have promoted functional diversification of the Sodalis SSR-2 type-III secretion system.

Keywords: adaptive evolution; type-III secretion system; symbiosis; neofunctionalization.
Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?


This article has been cited by other articles:


Home page
 Nucleic Acids ResHome page
N. Yabuta, H. Onda, M. Watanabe, N. Yoshioka, I. Nagamori, T. Funatsu, S. Toji, K. Tamai, and H. Nojima
Isolation and characterization of the TIGA genes, whose transcripts are induced by growth arrest
Nucleic Acids Res., October 18, 2006; 34(17): 4878 - 4892.
[Abstract] [Full Text] [PDF]

Home page
 Appl. Environ. Microbiol.Home page
C. Dale, M. Beeton, C. Harbison, T. Jones, and M. Pontes
Isolation, Pure Culture, and Characterization of "Candidatus Arsenophonus arthropodicus," an Intracellular Secondary Endosymbiont from the Hippoboscid Louse Fly Pseudolynchia canariensis
Appl. Envir. Microbiol., April 1, 2006; 72(4): 2997 - 3004.
[Abstract] [Full Text] [PDF]

Home page
 Genome ResHome page
H. Toh, B. L. Weiss, S. A.H. Perkin, A. Yamashita, K. Oshima, M. Hattori, and S. Aksoy
Massive genome erosion and functional adaptations provide insights into the symbiotic lifestyle of Sodalis glossinidius in the tsetse host
Genome Res., February 1, 2006; 16(2): 149 - 156.
[Abstract] [Full Text] [PDF]

Home page
 Proc. Natl. Acad. Sci. USAHome page
N. A. Moran, P. H. Degnan, S. R. Santos, H. E. Dunbar, and H. Ochman
Inaugural Article: The players in a mutualistic symbiosis: Insects, bacteria, viruses, and virulence genes
PNAS, November 22, 2005; 102(47): 16919 - 16926.
[Abstract] [Full Text] [PDF]

Home page
 PhysiologyHome page
P. Troisfontaines and G. R. Cornelis
Type III Secretion: More Systems Than You Think
Physiology, October 1, 2005; 20(5): 326 - 339.
[Abstract] [Full Text] [PDF]


Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.