Inducer expulsion in Streptococcus pyogenes: properties and mechanism of the efflux reaction

Journal Article · Fri Apr 01 00:00:00 EST 1988 · J. Bacteriol.; (United States)

OSTI ID:6956828

Sutrina, S L; Reizer, J; Saier, Jr, M H

Expulsion of preaccumulated methyl-..beta..-D-thiogalactoside-phosphate (TMG-P) from Streptococcus pyogenes is a two-step process comprising intracellular dephosphorylation of TMG-P followed by rapid efflux of the intracellularly formed free galactoside. The present study identifies the mechanism and the order and characterizes the temperature dependency of the efflux step. Unidirectional efflux of the intracellularly formed (/sup 14/C)TMG was only slightly affected when measured in the presence of unlabeled TMG (25 to 400 mM) in the extracellular medium. In contrast, pronounced inhibition of net efflux was observed in the presence of relatively low concentrations (1 to 16 mM) of extracellular (/sup 14/C)TMG. Since net efflux was nearly arrested when the external concentration of (/sup 14/C)TMG approached the intracellular concentration of this sugar, we propose that a facilitated diffusion mechanism is responsible for efflux and equilibration of TMG between the intracellular and extracellular milieus. The exit reaction was markedly dependent upon temperature, exhibited a high energy of activation (23 kcal (ca. 96 kJ) per mol), and followed first-order kinetics, indicating that the permease mediating this efflux was not saturated under the conditions of expulsion employed.

• Research Organization: Univ. of California, San Diego (USA)
• OSTI ID: 6956828
• Journal Information: J. Bacteriol.; (United States), Vol. 170:4
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CARBOHYDRATES
BIOCHEMICAL REACTION KINETICS
STREPTOCOCCUS
PHYSIOLOGY
BIOLOGICAL PATHWAYS
CARBON 14 COMPOUNDS
DIFFUSION
TEMPERATURE DEPENDENCE
TRACER TECHNIQUES
BACTERIA
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
MICROORGANISMS
ORGANIC COMPOUNDS
REACTION KINETICS
550201* - Biochemistry- Tracer Techniques