Wg. Zhu et al., The C terminus of AvrXa10 can be replaced by the transcriptional activation domain of VP16 from the herpes simplex virus, PL CELL, 11(9), 1999, pp. 1665-1674
The avirulence gene avrXa10 of Xanthomonas oryzae pv oryzae directs the eli
citation of resistance in a gene-for-gene manner in rice lines carrying the
resistance gene Xa10. We have localized a transcriptional activator domain
in the C terminus of AvrXa10 by using amino acid replacement mutagenesis.
One mutant, with replacements at three hydrophobic amino acid residues in t
he C-terminal domain, was defective for transcriptional activation in yeast
and avirulence activity in rice. The activation domain from the herpes vir
us protein VP16 restored the ability of the bacteria expressing the hybrid
protein to elicit a resistance reaction. Elicitation was specific for Xa10,
and the reaction had the hallmarks of the response to AvrXa10. The results
indicate that a domain with the properties of a transcriptional activator
plays a critical role in AvrXa10 function. The results also indicate that t
he protein has the potential to interact with the plant transcriptional pro
gram, although a role for the domain in the stability or conformation of th
e protein in the plant cannot be excluded. In a broader sense, the transcri
ptional activation domain of avrXa10 may represent a prokaryotic version of
the acidic transcriptional activation domain, which heretofore has been fo
und exclusively in eukaryotes.