Ornithine transport and exchange in Streptococcus lactis

Journal Article · Tue Sep 01 00:00:00 EDT 1987 · J. Bacteriol.; (United States)

OSTI ID:6066710

Thompson, J

Resting cells of Streptococcus lactis 133 appeared to accumulate (/sup 14/C)ornithine to a high concentration in the absence of an exogenous energy source. However, analysis of intracellular amino acid pool constituents and results of transport experiments revealed that the accumulation of ornithine represented a homoexchange between extracellular (/sup 14/C)ornithine and unlabeled ornithine in the cell. The energy-independent exchange of ornithine was not inhibited by proton-conducting uncouplers or by metabolic inhibitors. Intracellular (/sup 14/C)ornithine was retained by resting cells after suspension in a buffered medium. However, addition of unlabeled ornithine to the suspension elicited rapid exit of labeled amino acid. The initial rate of exist of (/sup 14/C)ornithine was dependent on the concentration of unlabeled ornithine in the medium, but this accelerative exchange diffusion process caused no net loss of amino acid. By contrast, the presence of a fermentable energy source caused a rapid expulsion of and new decrease in the concentration of intracellular ornithine. Kinetic analyses of amino acid transport demonstrated competitive inhibition between lysine and ornithine, and data obtained by two-dimensional thin-layer chromatography established the heteroexchange of these basic amino acids. The effects of amino acids and of ornithine analogs on both entry and exit of (/sup 14/C)ornithine have been examined. The data suggest that common carrier mediates the entry and exchange of lysine, arginine, and ornithine in cells of S. lactis.

• Research Organization: National Institute of Dental Research, Bethesda, MD
• OSTI ID: 6066710
• Journal Information: J. Bacteriol.; (United States), Vol. 169:9
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
ORNITHINE
BIOCHEMICAL REACTION KINETICS
STREPTOCOCCUS
METABOLISM
CARBON 14 COMPOUNDS
TRACER TECHNIQUES
AMINO ACIDS
BACTERIA
CARBOXYLIC ACIDS
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
MICROORGANISMS
ORGANIC ACIDS
ORGANIC COMPOUNDS
REACTION KINETICS
550701* - Microbiology- Tracer Techniques
550501 - Metabolism- Tracer Techniques