Fenyk, S. and de San Eustaquio Campillo, A. and Pohl, E. and Hussey, P.J. and Cann, M.J. (2012) 'A nucleotide phosphatase activity in the nucleotide binding domain of an orphan resistance protein from rice.', Journal of biological chemistry., 287 (6). pp. 4023-4032.
Plant resistance proteins (R-proteins) are key components of the plant immune system activated in response to a plethora of different pathogens. R-proteins are P-loop NTPase superfamily members, and current models describe their main function as ATPases in defense signaling pathways. Here we show that a subset of R-proteins have evolved a new function to combat pathogen infection. This subset of R-proteins possesses a nucleotide phosphatase activity in the nucleotide-binding domain. Related R-proteins that fall in the same phylogenetic clade all show the same nucleotide phosphatase activity indicating a conserved function within at least a subset of R-proteins. R-protein nucleotide phosphatases catalyze the production of nucleoside from nucleotide with the nucleotide monophosphate as the preferred substrate. Mutation of conserved catalytic residues substantially reduced activity consistent with the biochemistry of P-loop NTPases. Kinetic analysis, analytical gel filtration, and chemical cross-linking demonstrated that the nucleotide-binding domain was active as a multimer. Nuclear magnetic resonance and nucleotide analogues identified the terminal phosphate bond as the target of a reaction that utilized a metal-mediated nucleophilic attack by water on the phosphoester. In conclusion, we have identified a group of R-proteins with a unique function. This biochemical activity appears to have co-evolved with plants in signaling pathways designed to resist pathogen attack.
|Keywords:||Nucleoside, Nucleotide, Phosphatase, Plant Biochemistry, Recombinant Protein Expression, Resistance Protein.|
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|Publisher Web site:||http://dx.doi.org/10.1074/jbc.M111.314450|
|Publisher statement:||Full-text available under a Creative Commons Attribution Non-Commercial License.|
|Record Created:||01 Jun 2012 17:35|
|Last Modified:||06 Jun 2012 10:07|
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