Formation of the chlorophyll precursor. gamma. -aminolevulinic acid in cyanobacteria requires aminoacylation of a tRNA sup Glu species. [Synechocystis]

Journal Article · Thu Sep 01 00:00:00 EDT 1988 · Journal of Bacteriology; (USA)

OSTI ID:7266947

O'Nell, G P; Peterson, D M; Soell, D ^[1]

---

1. Yale Univ., New Haven, CT (USA)

In the chloroplasts of higher plants and algae, the biosynthesis of the chlorophyll precursor {gamma}-aminolevulinic acid (ALA) involves at least three enzymes and a tRNA species. Here we demonstrate that in cell extracts of the unicellular cyanobacterium Synechocystis sp. strain PCC 6803 ALA was formed from glutamate in a series of reactions in which activation of glutamate by glutamyl-tRNA{sup Glu} formation was the first step. The activated glutamate was reduced by a dehydrogenase which displayed tRNA sequence specificity. Fractionation of strain 6803 tRNA by reverse-phase chromatography and polyacrylamide gel electrophoresis yielded two pure tRNA{sup Glu} species which stimulated ALA synthesis in vitro. These tRNAs had identical primary sequence but differed in the nucleotide modification of their anticodon. The 6803 tRNA{sup Glu} was similar to the sequence of tRNA{sup Glu} species or tRNA genes from Escherichia coli and from chloroplasts of Euglena gracilis and higher plants. Southern blot analysis revealed at least two tRNA{sup Glu} gene copies in the 6803 chromosome. A glutamate-1-semialdehyde aminotransferase, the terminal enzyme in the conversion of glutamate to ALA in chloroplasts, was detected in 6803 cell extracts by the conversion of glutamate-1-semialdehyde to ALA and by the inhibition of this reaction by gabaculin.

• OSTI ID: 7266947
• Journal Information: Journal of Bacteriology; (USA), Vol. 170:9; ISSN 0021-9193
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
AMINOLEVULINIC ACID
BIOSYNTHESIS
CYANOBACTERIA
PHOTOSYNTHESIS
TRANSFER RNA
ACYLATION
AMINO ACID SEQUENCE
AMINOTRANSFERASES
BIOLOGICAL PATHWAYS
CHLOROPHYLL
CHLOROPLASTS
CHROMATOGRAPHY
CHROMOSOMES
ELECTROPHORESIS
GENES
GLUTAMIC ACID
PRECURSOR
AMINO ACIDS
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CHEMICAL REACTIONS
ENZYMES
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
MICROORGANISMS
MOLECULAR STRUCTURE
NITROGEN TRANSFERASES
NUCLEIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHYTOCHROMES
PIGMENTS
PORPHYRINS
PROTEINS
RNA
SEPARATION PROCESSES
SYNTHESIS
TRANSFERASES
550200* - Biochemistry