Functional and immunochemical characterization of a mutant of Escherichia coli energy uncoupled for lactose transport

Journal Article · Tue Jan 01 00:00:00 EST 1985 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00322a032· OSTI ID:5023278

Herzlinger, D; Carrasco, N; Kaback, H R

Right-side-out cytoplasmic membrane vesicles from Escherichia coli ML 308-22, a mutant ''uncoupled'' for beta-galactoside/H/sup +/ symport are specifically defective in the ability to catalyze accumulation of methyl 1-thio-beta-D-galactopyranoside (TMG) in the presence of an H/sup +/ electrochemical gradient (interior negative and alkaline). Furthermore, the rate of carrier-mediated efflux under nonenergized conditions is slow and unaffected by ambient pH from pH 5.5 to 7.5, and TMG-induced H/sup +/ influx is only about 15% of that observed in vesicles containing wild-type lac permease (ML 308-225). Alternatively, ML 308-22 vesicles bind p-nitrophenyl alpha-D-galactopyranoside and monoclonal antibody 4B1 to the same extent as ML 308-225 vesicles and catalyze facilitated diffusion and equilibrium exchange as well as ML 308-225 vesicles. When entrance counterflow is studied with external substrate at saturating and subsaturating concentrations, it is apparent that the mutation simulates the effects of deuterium oxide. That is, the mutation has no effect on the rate or extent of counterflow when external substrate is saturating but stimulates the efficiency of counterflow when external substrate is below the apparent K/sub m/. Moreover, although replacement of protium with deuterium stimulates counterflow in ML 308-225 vesicles when external substrate is subsaturating, the isotope has no effect on the mutant vesicles under the same conditions.

• OSTI ID: 5023278
• Journal Information: Biochemistry; (United States), Vol. 1
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
LACTOSE
MEMBRANE TRANSPORT
MEMBRANE PORES
BIOCHEMICAL REACTION KINETICS
CARBON ISOTOPES
CELL MEMBRANES
DEUTERIUM COMPOUNDS
ESCHERICHIA COLI
KINETICS
MONOCLONAL ANTIBODIES
MONOSACCHARIDES
MUTANTS
PH VALUE
PROLINE
TRACER TECHNIQUES
AMINES
AMINO ACIDS
ANTIBODIES
AZOLES
BACTERIA
CARBOHYDRATES
CARBOXYLIC ACIDS
CELL CONSTITUENTS
DISACCHARIDES
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
ISOTOPE APPLICATIONS
ISOTOPES
MEMBRANES
MICROORGANISMS
OLIGOSACCHARIDES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PYRROLES
PYRROLIDINES
REACTION KINETICS
SACCHARIDES
550201* - Biochemistry- Tracer Techniques