אסיף מאגר המחקר החקלאי

Structural and biochemical studies identify tobacco SABP2 as a methyl salicylate esterase and implicate it in plant innate immunity

Year:

2005

Source of publication :

Authors :

Volume :

102

Co-Authors:

Forouhar, F., Department of Biological Sciences, NE Structural Genomics Consortium, Columbia University, New York, NY 10027, United States
Yang, Y., Dept. Molec., Cell., Devmtl. Biol., University of Michigan, Ann Arbor, MI 48109, United States
Kumar, D., Boyce Thompson Inst. for Plant Res., Tower Road, Ithaca, NY 14853, United States
Chen, Y., Department of Biological Sciences, NE Structural Genomics Consortium, Columbia University, New York, NY 10027, United States
Fridman, E., Dept. Molec., Cell., Devmtl. Biol., University of Michigan, Ann Arbor, MI 48109, United States
Park, S.W., Boyce Thompson Inst. for Plant Res., Tower Road, Ithaca, NY 14853, United States
Chiang, Y., Dept. of Molec. Biol. and Biochem., Rutgers University, Robert Wood Johnson Medical School, Piscataway, NJ 08854, United States, Department of Biochemistry, Robert Wood Johnson Medical School, Piscataway, NJ 08854, United States
Acton, T.B., Dept. of Molec. Biol. and Biochem., Rutgers University, Robert Wood Johnson Medical School, Piscataway, NJ 08854, United States, Department of Biochemistry, Robert Wood Johnson Medical School, Piscataway, NJ 08854, United States
Montelione, G.T., Dept. of Molec. Biol. and Biochem., Rutgers University, Robert Wood Johnson Medical School, Piscataway, NJ 08854, United States, Department of Biochemistry, Robert Wood Johnson Medical School, Piscataway, NJ 08854, United States
Pichersky, E., Dept. Molec., Cell., Devmtl. Biol., University of Michigan, Ann Arbor, MI 48109, United States
Klessig, D.F., Boyce Thompson Inst. for Plant Res., Tower Road, Ithaca, NY 14853, United States
Tong, L., Department of Biological Sciences, NE Structural Genomics Consortium, Columbia University, New York, NY 10027, United States

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Abstract:

Salicylic acid (SA) is a critical signal for the activation of plant defense responses against pathogen infections. We recently identified SA-binding protein 2 (SABP2) from tobacco as a protein that displays high affinity for SA and plays a crucial role in the activation of systemic acquired resistance to plant pathogens. Here we report the crystal structures of SABP2, alone and in complex with SA at up to 2.1-Å resolution. The structures confirm that SABP2 is a member of the α/β hydrolase superfamily of enzymes, with Ser-81, His-238, and Asp-210 as the catalytic triad. SA is bound in the active site and is completely shielded from the solvent, consistent with the high affinity of this compound for SABP2. Our biochemical studies reveal that SABP2 has strong esterase activity with methyl salicylate as the substrate, and that SA is a potent product inhibitor of this catalysis. Modeling of SABP2 with MeSA in the active site is consistent with all these biochemical observations. Our results suggest that SABP2 may be required to convert MeSA to SA as part of the signal transduction pathways that activate systemic acquired resistance and perhaps local defense responses as well.

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