The N- and C-Terminal Portions of the Agrobacterium VirB1 Protein Independently Enhance Tumorigenesis
AUTOR(ES)
Llosa, Matxalen
FONTE
American Society for Microbiology
RESUMO
Genetic transformation of plants by Agrobacterium tumefaciens is mediated by a virulence (vir)-specific type IV secretion apparatus assembled from 11 VirB proteins and VirD4. VirB1, targeted to the periplasm by an N-terminal signal peptide, is processed to yield VirB1*, comprising the C-terminal 73 amino acids. The N-terminal segment, which shares homology with chicken egg white lysozyme as well as lytic transglycosylases, may provide local lysis of the peptidoglycan cell wall to create channels for transporter assembly. Synthesis of VirB1* followed by its secretion to the exterior of the cell suggests that VirB1* may also have a role in virulence. In the present study, we provide evidence for the dual roles of VirB1 in tumorigenesis as well as the requirements for processing and secretion of VirB1*. Complementation of a virB1 deletion strain with constructs expressing either the N-terminal lysozyme-homologous region or VirB1* results in tumors intermediate in size between those induced by a wild-type strain and a virB1 deletion strain, suggesting that each domain has a unique role in tumorigenesis. The secretion of VirB1* translationally fused to the signal peptide indicates that processing and secretion are not coupled. When expressed independently of all other vir genes, VirB1 was processed and VirB1* was secreted. When restricted to the cytoplasm by deletion of the signal peptide, VirB1 was neither processed nor secreted and did not restore virulence to the virB1 deletion strain. Thus, factors that mediate processing of VirB1 and secretion of VirB1* are localized in the periplasm or outer membrane and are not subject to vir regulation.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=101919Documentos Relacionados
- VirB1, a component of the T-complex transfer machinery of Agrobacterium tumefaciens, is processed to a C-terminal secreted product, VirB1.
- The N- and C-Terminal Domains of the NS1 Protein of Influenza B Virus Can Independently Inhibit IRF-3 and Beta Interferon Promoter Activation
- Differential Requirements for VirB1 and VirB2 during Brucella abortus Infection
- The signal response of IkappaB alpha is regulated by transferable N- and C-terminal domains.
- Signaling by N- and C-terminal sequences of parathyroid hormone-related protein in hippocampal neurons.