Primary Citation of Related Structures: 4PSB, 4Q0K
PubMed Abstract:
Pathogenesis-related proteins of class 10 (PR-10) are a family of plant proteins with the same fold characterized by a large hydrophobic cavity that allows them to bind various ligands, such as phytohormones. A subfamily with only ~20% sequence identity but with a conserved canonical PR-10 fold have previously been recognized as Cytokinin-Specific Binding Proteins (CSBPs), although structurally the binding mode of trans-zeatin (a cytokinin phytohormone) was found to be quite diversified ...
Pathogenesis-related proteins of class 10 (PR-10) are a family of plant proteins with the same fold characterized by a large hydrophobic cavity that allows them to bind various ligands, such as phytohormones. A subfamily with only ~20% sequence identity but with a conserved canonical PR-10 fold have previously been recognized as Cytokinin-Specific Binding Proteins (CSBPs), although structurally the binding mode of trans-zeatin (a cytokinin phytohormone) was found to be quite diversified. Here, it is shown that two CSBP orthologues from Medicago truncatula and Vigna radiata bind gibberellic acid (GA3), which is an entirely different phytohormone, in a conserved and highly specific manner. In both cases a single GA3 molecule is found in the internal cavity of the protein. The structural data derived from high-resolution crystal structures are corroborated by isothermal titration calorimetry (ITC), which reveals a much stronger interaction with GA3 than with trans-zeatin and pH dependence of the binding profile. As a conclusion, it is postulated that the CSBP subfamily of plant PR-10 proteins should be more properly linked with general phytohormone-binding properties and termed phytohormone-binding proteins (PhBP).
Related Citations:
Crystal structure of Vigna radiata cytokinin-specific binding protein in complex with zeatin. Pasternak, O., Bujacz, G.D., Fujimoto, Y., Hashimoto, Y., Jelen, F., Otlewski, J., Sikorski, M.M., Jaskolski, M. (2006) Plant Cell 18: 2622
Crystal structures of two homologous pathogenesis-related proteins from yellow lupine. Biesiadka, J., Bujacz, G., Sikorski, M.M., Jaskolski, M. (2002) J Mol Biol 319: 1223
The landscape of cytokinin binding by a plant nodulin. Ruszkowski, M., Szpotkowski, K., Sikorski, M., Jaskolski, M. (2013) Acta Crystallogr D Biol Crystallogr 69: 2365
Lupinus luteus pathogenesis-related protein as a reservoir for cytokinin. Fernandes, H., Pasternak, O., Bujacz, G., Bujacz, A., Sikorski, M.M., Jaskolski, M. (2008) J Mol Biol 378: 1040
Structural and functional aspects of PR-10 proteins. Fernandes, H., Michalska, K., Sikorski, M., Jaskolski, M. (2013) FEBS J 280: 1169
Organizational Affiliation:
Center for Biocrystallographic Research, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Poland.
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