Functional analyses of carnivorous plant-specific amino acid residues in S-like ribonucleases

Naoki Arai, Emi Nishimura, Yo Kikuchi, Takashi Ohyama*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

Unlike plants with no carnivory, carnivorous plants seem to use S-like ribonucleases (RNases) as an enzyme for carnivory. Carnivorous plant-specific conserved amino acid residues are present at four positions around the conserved active site (CAS). The roles of these conserved amino acid residues in the enzymatic function were explored in the current study by preparing five recombinant variants of DA-I, the S-like RNase of Drosera adelae. The kcat and kcat/Km values of the enzymes revealed that among the four variants with a single mutation, the serine to glycine mutation at position 111 most negatively influenced the enzymatic activity. The change in the bulkiness of the amino acid residue side-chain seemed to be the major cause of the above effect. Modeling of the three dimensional (3D) structures strongly suggested that the S to G mutation at 111 greatly altered the overall enzyme conformation. The conserved four amino acid residues are likely to function in keeping the two histidine residues, which are essential for the cleavage of RNA strands, and the CAS in the most functional enzymatic conformation.

Original languageEnglish
Article number34351
Pages (from-to)108-112
Number of pages5
JournalBiochemical and Biophysical Research Communications
Volume465
Issue number1
DOIs
Publication statusPublished - 2015 Jul 30

Keywords

  • Carnivorous plants
  • Drosera adelae
  • Protein structure
  • S-like ribonuclease
  • k<inf>cat</inf>/K<inf>m</inf>

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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