Identification of Active-Site Histidine Residues of a Self-Incompatibility Ribonuclease from a Wild Tomato

DOI PDF 被引用文献4件
  • S. Parry
    Plant Cell Biology Research Centre, School of Botany, University of Melbourne, Parkville, Victoria 3052, Australia
  • E. Newbigin
    Plant Cell Biology Research Centre, School of Botany, University of Melbourne, Parkville, Victoria 3052, Australia
  • G. Currie
    Plant Cell Biology Research Centre, School of Botany, University of Melbourne, Parkville, Victoria 3052, Australia
  • A. Bacic
    Plant Cell Biology Research Centre, School of Botany, University of Melbourne, Parkville, Victoria 3052, Australia
  • D. Oxley
    Plant Cell Biology Research Centre, School of Botany, University of Melbourne, Parkville, Victoria 3052, Australia

抄録

<jats:title>Abstract</jats:title> <jats:p>The style component of the self-incompatibility (S) locus of the wild tomato Lycopersicon peruvianum (L.) Mill. is an allelic series of glycoproteins with ribonuclease activity (S-RNases). Treatment of the S3-RNase from L. peruvianum with iodoacetate at pH 6.1 led to a loss of RNase activity. In the presence of a competitive inhibitor, guanosine 3[prime]-monophosphate (3[prime]-GMP), the rate of RNase inactivation by iodoacetate was reduced significantly. Analysis of the tryptic digestion products of the iodoacetate-modified S-RNase by reversed-phase high-performance liquid chromatography and electrospray-ionization mass spectrometry showed that histidine-32 was preferentially modified in the absence of 3[prime]-GMP. Histidine-88 was also modified, but this occurred both in the presence and absence of 3[prime]-GMP, suggesting that this residue is accessible when 3[prime]-GMP is in the active site. Cysteine-150 was modified by iodoacetate in the absence of 3[prime]-GMP and, to a lesser extent, in its presence. The results are discussed with respect to the related fungal RNase T2 family and the mechanism of S-RNase action.</jats:p>

収録刊行物

  • Plant Physiology

    Plant Physiology 115 (4), 1421-1429, 1997-12-01

    Oxford University Press (OUP)

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