Document Detail


Agrobacterium type IV secretion system and its substrates form helical arrays around the circumference of virulence-induced cells.
MedLine Citation:
PMID:  20133577     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The genetic transformation of plant cells by Agrobacterium tumefaciens results from the transfer of DNA and proteins via a specific virulence (vir) -induced type IV secretion system (T4SS). To better understand T4SS function, we analyzed the localization of its structural components and substrates by deconvolution fluorescence microscopy. GFP fusions to T4SS proteins with cytoplasmic tails, VirB8 and VirD4, or cytoplasmic T4SS substrate proteins, VirD2, VirE2, and VirF, localize in a helical pattern of fluorescent foci around the perimeter of the bacterial cell. All fusion proteins were expressed at native levels of vir induction. Importantly, most fusion proteins are functional and do not exhibit dominant-negative effects on DNA transfer to plant cells. Further, GFP-VirB8 complements a virB8 deletion strain. We also detect native VirB8 localization as a helical array of foci by immunofluorescence microscopy. T4SS foci likely use an existing helical scaffold during their assembly. Indeed, the bacterial cytoskeletal component MinD colocalizes with GFP-VirB8. Helical arrays of foci are found at all times investigated between 12 and 48 h post vir induction at 19 degrees C. These data lead to a model with multiple T4SSs around the bacterial cell that likely facilitate host cell attachment and DNA transfer. In support, we find multiple T pili around vir-induced bacterial cells.
Authors:
Julieta Aguilar; John Zupan; Todd A Cameron; Patricia C Zambryski
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2010-02-02
Journal Detail:
Title:  Proceedings of the National Academy of Sciences of the United States of America     Volume:  107     ISSN:  1091-6490     ISO Abbreviation:  Proc. Natl. Acad. Sci. U.S.A.     Publication Date:  2010 Feb 
Date Detail:
Created Date:  2010-02-25     Completed Date:  2010-04-05     Revised Date:  2010-09-28    
Medline Journal Info:
Nlm Unique ID:  7505876     Medline TA:  Proc Natl Acad Sci U S A     Country:  United States    
Other Details:
Languages:  eng     Pagination:  3758-63     Citation Subset:  IM    
Affiliation:
Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
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MeSH Terms
Descriptor/Qualifier:
Bacterial Proteins / metabolism*
Cytoplasm / metabolism
DNA-Binding Proteins / metabolism*
Fimbriae, Bacterial / metabolism,  ultrastructure
Green Fluorescent Proteins / metabolism
Ion Channels / metabolism*
Microscopy, Fluorescence
Recombinant Fusion Proteins / metabolism
Rhizobium radiobacter / metabolism*,  pathogenicity*,  ultrastructure
Virulence
Chemical
Reg. No./Substance:
0/Bacterial Proteins; 0/DNA-Binding Proteins; 0/Ion Channels; 0/Recombinant Fusion Proteins; 0/virE2 protein, Agrobacterium; 147336-22-9/Green Fluorescent Proteins
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