Purification and Partial Characterisation of Barley glutamyl-tRNA(Glu) Reductase, the Enzyme That Directs Glutamate to Chlorophyll Biosynthesis

Eur J Biochem. 1994 Oct 15;225(2):529-37. doi: 10.1111/j.1432-1033.1994.00529.x.

Abstract

5-Aminolevulinic acid for chlorophyll synthesis in greening barley is formed from glutamate. One of the steps involved in the conversion of glutamate to 5-aminolevulinic acid involves a reduction of glutamyl-tRNA(Glu) to glutamate 1-semialdehyde and tRNA(Glu). An enzyme catalysing this reduction was purified from the stroma of greening barley chloroplasts. An approximately 270-kDa protein composed of 54-kDa identical subunits was identified as the barley glutamyl-tRNA(Glu) reductase after purification by Sephacryl S-300, Cibacron Blue-Sepharose, 2'-5'-ADP-Sepharose, Mono S, Mini Q and Superose 12 chromatography. The sequence of 18 amino acids from the N-terminus of the reductase is 50% identical to a cDNA-deduced domain of the Arabidopsis thaliana hemA protein and encoded in a barley hemA cDNA sequence. This is an unequivocal demonstration that the glutamyl-tRNA(Glu) reductase subunit of higher plants is encoded in a hemA gene of the nuclear genome. Heme at 4 microM concentration or glutamate 1-semialdehyde at 200 microM caused a 50% inhibition of the reductase activity. Micromolar concentrations of Zn2+, Cu2+ and Cd2+ also inhibited barley glutamyl-tRNA(Glu) reductase.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aldehyde Oxidoreductases / chemistry
  • Aldehyde Oxidoreductases / isolation & purification*
  • Aldehyde Oxidoreductases / metabolism
  • Amino Acid Sequence
  • Arabidopsis / chemistry
  • Chlorophyll / biosynthesis*
  • Chloroplasts / enzymology
  • Chromatography, Affinity
  • Chromatography, Gel
  • Glutamic Acid / biosynthesis*
  • Hordeum / enzymology*
  • Molecular Sequence Data
  • Molecular Weight
  • Sequence Homology, Amino Acid

Substances

  • Chlorophyll
  • Glutamic Acid
  • Aldehyde Oxidoreductases
  • glutamyl tRNA reductase