The virulence region of the Ti plasmid mediates the transfer of T DNA and its integration into the plant genome.
- Vir region is organised into 8 operons, vir A to H
- And has approximately 25 genes.
- Vir region mediates the transfer of T-DNA to the plant genome.
Vir genes
|
Function
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Vir A
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Encodes acetosyringone receptor protein, also activates vir G by phosphprylation leading to constitutive expression of all genes.
|
Vir B
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Encodes membrane protein, involved in conjugal tube formation through which T-DNA is transport.
|
Vir C
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Encodes helicase enzyme; unwinding of T-DNA
|
Vir D
|
Topoisomerase activity; vir D2 is an endonucleases
|
Vir E
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Single strand binding protein (SSBP);binds to T-DNA during transfer
|
Vir F
|
Activity not known
|
Vir G
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Master controller DNA binding protein; VirA activates vir G by phosphorylation, vir G dimerises and activates constitutive expression of all vir operons
|
Vir H
|
Activity not known
|
All vir genes works in harmony to effect a successful T-DNA transfer into the plant genome.