Involvement of coenzyme A thioesters in anaerobic metabolism of 4-hydroxybenzoate by Rhodopseudomonas palustris

Journal Article · Sun Jan 01 04:00:00 EST 1989 · J. Bacteriol.; (United States)

OSTI ID:6270867

Merkel, S M; Eberhard, A E; Gibson, J; Harwood, C S

The initial steps of anaerobic 4-hydroxybenzoate degradation were studied in whole cells and cell extracts of the photosynthetic bacterium Rhodopseudomonas palustris. Illuminated suspensions of cells that had been grown anaerobically on 4-hydroxybenzoate and were assayed under anaerobic conditions took up (U-14C)4-hydroxybenzoate at a rate of 0.6 nmol min-1 mg of protein-1. Uptake occurred with high affinity (apparent Km = 0.3 microM), was energy dependent, and was insensitive to external pH in the range of 6.5 to 8.2 Very little free 4-hydroxybenzoate was found associated with cells, but a range of intracellular products was formed after 20-s incubations of whole cells with labeled substrate. When anaerobic pulse-chase experiments were carried out with cells incubated on ice or in darkness, 4-hydroxybenzoyl coenzyme A (4-hydroxybenzoyl-CoA) was formed early and disappeared immediately after addition of excess unlabeled substrate, as would be expected of an early intermediate in 4-hydroxybenzoate metabolism. A 4-hydroxybenzoate-CoA ligase activity with an average specific activity of 0.7 nmol min-1 mg of protein-1 was measured in the soluble protein fraction of cells grown anaerobically on 4-hydroxybenzoate. 4-Hydroxybenzoyl-CoA was the sole product formed from labeled 4-hydroxybenzoate in the ligase reaction mixture. 4-Hydroxybenzoate uptake and ligase activities were present in cells grown anaerobically with benzoate, 4-hydroxybenzoate, and 4-aminobenzoate and were not detected in succinate-grown cells.

• Research Organization: Cornell Univ., Ithaca, NY (USA)
• OSTI ID: 6270867
• Journal Information: J. Bacteriol.; (United States), Journal Name: J. Bacteriol.; (United States) Vol. 171:1; ISSN JOBAA
• Country of Publication: United States
• Language: English

Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANAEROBIC CONDITIONS
BACTERIA
BENZOIC ACID
CARBON 14 COMPOUNDS
CARBOXYLIC ACIDS
ENZYME ACTIVITY
ENZYMES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LIGASES
METABOLISM
MICROORGANISMS
MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
RHODOPSEUDOMONAS
TRACER TECHNIQUES