Discovery of a Cytokinin Deaminase

ACS Chem Biol. 2011 Oct 21;6(10):1036-40. doi: 10.1021/cb200198c. Epub 2011 Aug 12.

Abstract

An enzyme of unknown function within the amidohydrolase superfamily was discovered to catalyze the hydrolysis of N-6-substituted adenine derivatives, several of which are cytokinins. Cytokinins are a common type of plant hormone and N-6-substituted adenines are also found as modifications to tRNA. Patl2390, from Pseudoalteromonas atlantica T6c, was shown to hydrolytically deaminate N-6-isopentenyladenine to hypoxanthine and isopentenylamine with a k(cat)/K(m) of 1.2 × 10(7) M(-1) s(-1). Additional substrates include N-6-benzyl adenine, cis- and trans-zeatin, kinetin, O-6-methylguanine, N-6-butyladenine, N-6-methyladenine, N,N-dimethyladenine, 6-methoxypurine, 6-chloropurine, and 6-thiomethylpurine. This enzyme does not catalyze the deamination of adenine or adenosine. A comparative model of Patl2390 was computed using the three-dimensional crystal structure of Pa0148 (PDB code 3PAO ) as a structural template, and docking was used to refine the model to accommodate experimentally identified substrates. This is the first identification of an enzyme that will hydrolyze an N-6-substituted side chain larger than methylamine from adenine.

Publication types

  • Letter
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenine / analogs & derivatives
  • Adenine / metabolism
  • Aminohydrolases / chemistry
  • Aminohydrolases / metabolism*
  • Cytokinins / metabolism*
  • Deamination
  • Models, Molecular
  • Pseudomonas / chemistry
  • Pseudomonas / enzymology*
  • Pseudomonas aeruginosa / enzymology
  • Substrate Specificity

Substances

  • Cytokinins
  • Aminohydrolases
  • Adenine