Substrate induction of conjugative activity of Agrobacterium tumefaciens Ti plasmids

Nature ◽  
1978 ◽  
Vol 271 (5645) ◽  
pp. 570-572 ◽  
Author(s):  
A. PETIT ◽  
J. TEMPE ◽  
A. KERR ◽  
M. HOLSTERS ◽  
M. VAN MONTAGU ◽  
...  
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Ti Plasmids ◽  
Substrate Induction

scholarly journals The Presence and Characterization of a virF Gene on Agrobacterium vitis Ti Plasmids

1998 ◽  
Vol 11 (5) ◽  
pp. 429-433 ◽  
Author(s):  
B. Schrammeijer ◽  
J. Hemelaar ◽  
P. J. J. Hooykaas
Keyword(s):  
Amino Acids ◽  
Agrobacterium Tumefaciens ◽  
Molecular Mass ◽  
Promoter Region ◽  
Consensus Sequence ◽  
Tumor Formation ◽  
Nicotiana Glauca ◽  
Agrobacterium Vitis ◽  
Ti Plasmids

Octopine and nopaline strains of Agrobacterium tumefaciens differ in their ability to induce tumors on Nicotiana glauca. The presence of a virF locus on the octopine Ti plasmid makes N. glauca a host plant for these strains, indicating that the VirF protein is a host-range determinant. Here we show the presence of a virF locus not only on the Agrobacterium vitis octopine/cucumopine plasmids pTiAg57 and pTiTm4, but also on the nopaline Ti plas-mids pTiAT1, pTiAT66a, and pTiAT66b. On the octopine Ti plasmids from A. tumefaciens the virF gene is located between the virE locus and the left border of the T-region. In contrast, the virF gene on Ti plasmids of A. vitis is located at the very left end of the vir-region near the virA locus. The virF gene of pTiAg57 has been sequenced and codes for a protein of 202 amino acids with a molecular mass of 22,280 Da. Comparison showed that the virF gene from A. vitis strain Ag57 is almost identical to that from A. tumefaciens octopine strains. The transcription of the pTiAg57 virF is inducible by the plant phenolic compound acetosyringone through the presence of a vir-box consensus sequence in its promoter region. The VirF protein from pTiAg57 can complement octopine A. tumefaciens strains deleted for virF as shown by tumor formation on N. glauca.

scholarly journals Transsexuality in the Rhizosphere: Quorum Sensing Reversibly Converts Agrobacterium tumefaciens from Phenotypically Female to Male

2009 ◽  
Vol 191 (10) ◽  
pp. 3375-3383 ◽  
Author(s):  
Hongbaek Cho ◽  
Uelinton M. Pinto ◽  
Stephen C. Winans
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Quorum Sensing ◽  
Host Cell ◽  
Ti Plasmid ◽  
Conjugative Plasmids ◽  
Acylhomoserine Lactone ◽  
Ti Plasmids ◽  
Quorum Sensing Signals

ABSTRACT Conjugative plasmids generally encode proteins that block the conjugative entry of identical or similar plasmids into the host cell, a phenomenon known as entry exclusion. Here, we demonstrate that two Ti plasmids of Agrobacterium tumefaciens encode robust entry exclusion functions. Two proteins, TrbJ and TrbK, can each mediate entry exclusion and act synergistically. The trbJ and trbK genes are included within the trb operon, which is tightly regulated by the quorum-sensing regulator TraR and the cognate acylhomoserine lactone. In the absence of quorum-sensing signals, these proteins are not significantly expressed, and cells lacking TrbJ and TrbK are efficient Ti plasmid recipients. In the presence of these signals, these strains block the entry of Ti plasmids and instead become efficient conjugal donors.

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