Cargando…
Crystal structure of Spa40, the specificity switch for the Shigella flexneri type III secretion system
The pathogenic bacterium Shigella flexneri uses a type III secretion system to inject virulence factors from the bacterial cytosol directly into host cells. The machinery that identifies secretion substrates and controls the export of extracellular components and effector proteins consists of severa...
Autores principales: | , , , , , |
---|---|
Formato: | Texto |
Lenguaje: | English |
Publicado: |
Blackwell Publishing Ltd
2008
|
Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2615192/ https://www.ncbi.nlm.nih.gov/pubmed/18485071 http://dx.doi.org/10.1111/j.1365-2958.2008.06293.x |
_version_ | 1782163292428435456 |
---|---|
author | Deane, Janet E Graham, Stephen C Mitchell, Edward P Flot, David Johnson, Steven Lea, Susan M |
author_facet | Deane, Janet E Graham, Stephen C Mitchell, Edward P Flot, David Johnson, Steven Lea, Susan M |
author_sort | Deane, Janet E |
collection | PubMed |
description | The pathogenic bacterium Shigella flexneri uses a type III secretion system to inject virulence factors from the bacterial cytosol directly into host cells. The machinery that identifies secretion substrates and controls the export of extracellular components and effector proteins consists of several inner-membrane and cytoplasmic proteins. One of the inner membrane components, Spa40, belongs to a family of proteins proposed to regulate the switching of substrate specificity of the export apparatus. We show that Spa40 is cleaved within the strictly conserved amino acid sequence NPTH and substitution of the proposed autocatalytic residue abolishes cleavage. Here we also report the crystal structure of the cytoplasmic complex Spa40(C) and compare it with the recent structures of the homologues from Escherichia coli and Salmonella typhimurium. These structures reveal the tight association of the cleaved fragments and show that the conserved NPTH sequence lies on a loop which, when cleaved, swings away from the catalytic N257 residue, resulting in different surface features in this region. This structural rearrangement suggests a mechanism by which non-cleaving forms of these proteins interfere with correct substrate switching of the apparatus. |
format | Text |
id | pubmed-2615192 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2008 |
publisher | Blackwell Publishing Ltd |
record_format | MEDLINE/PubMed |
spelling | pubmed-26151922009-01-12 Crystal structure of Spa40, the specificity switch for the Shigella flexneri type III secretion system Deane, Janet E Graham, Stephen C Mitchell, Edward P Flot, David Johnson, Steven Lea, Susan M Mol Microbiol Research Articles The pathogenic bacterium Shigella flexneri uses a type III secretion system to inject virulence factors from the bacterial cytosol directly into host cells. The machinery that identifies secretion substrates and controls the export of extracellular components and effector proteins consists of several inner-membrane and cytoplasmic proteins. One of the inner membrane components, Spa40, belongs to a family of proteins proposed to regulate the switching of substrate specificity of the export apparatus. We show that Spa40 is cleaved within the strictly conserved amino acid sequence NPTH and substitution of the proposed autocatalytic residue abolishes cleavage. Here we also report the crystal structure of the cytoplasmic complex Spa40(C) and compare it with the recent structures of the homologues from Escherichia coli and Salmonella typhimurium. These structures reveal the tight association of the cleaved fragments and show that the conserved NPTH sequence lies on a loop which, when cleaved, swings away from the catalytic N257 residue, resulting in different surface features in this region. This structural rearrangement suggests a mechanism by which non-cleaving forms of these proteins interfere with correct substrate switching of the apparatus. Blackwell Publishing Ltd 2008-07 2008-05-29 /pmc/articles/PMC2615192/ /pubmed/18485071 http://dx.doi.org/10.1111/j.1365-2958.2008.06293.x Text en © 2008 The Authors Journal compilation © 2008 Blackwell Publishing Ltd |
spellingShingle | Research Articles Deane, Janet E Graham, Stephen C Mitchell, Edward P Flot, David Johnson, Steven Lea, Susan M Crystal structure of Spa40, the specificity switch for the Shigella flexneri type III secretion system |
title | Crystal structure of Spa40, the specificity switch for the Shigella flexneri type III secretion system |
title_full | Crystal structure of Spa40, the specificity switch for the Shigella flexneri type III secretion system |
title_fullStr | Crystal structure of Spa40, the specificity switch for the Shigella flexneri type III secretion system |
title_full_unstemmed | Crystal structure of Spa40, the specificity switch for the Shigella flexneri type III secretion system |
title_short | Crystal structure of Spa40, the specificity switch for the Shigella flexneri type III secretion system |
title_sort | crystal structure of spa40, the specificity switch for the shigella flexneri type iii secretion system |
topic | Research Articles |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2615192/ https://www.ncbi.nlm.nih.gov/pubmed/18485071 http://dx.doi.org/10.1111/j.1365-2958.2008.06293.x |
work_keys_str_mv | AT deanejanete crystalstructureofspa40thespecificityswitchfortheshigellaflexneritypeiiisecretionsystem AT grahamstephenc crystalstructureofspa40thespecificityswitchfortheshigellaflexneritypeiiisecretionsystem AT mitchelledwardp crystalstructureofspa40thespecificityswitchfortheshigellaflexneritypeiiisecretionsystem AT flotdavid crystalstructureofspa40thespecificityswitchfortheshigellaflexneritypeiiisecretionsystem AT johnsonsteven crystalstructureofspa40thespecificityswitchfortheshigellaflexneritypeiiisecretionsystem AT leasusanm crystalstructureofspa40thespecificityswitchfortheshigellaflexneritypeiiisecretionsystem |