Membrane transport proteins that transduce free energy stored in electrochemical ion gradients into a concentration gradient are major class of membrane proteins. We report the crystal structure at 3.5 angstroms Escherichia coli lactose permease, an intensively studied member facilitator superfamily transporters. The molecule is composed N- and C-terminal domains, each with six transmembrane helices, symmetrically positioned within permease. A large internal hydrophilic cavity open to...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMechanisms of active transport in isolated bacterial membrane vesicles. 28. Membrane potential and vesicles from Escherichia coliShimon Schuldiner H. Ronald KabackCite this: Biochemistry 1975, 14, 25, 5451–5461Publication Date (Print):December 16, 1975Publication History Published online1 May 2002Published inissue 16 December 1975https://pubs.acs.org/doi/10.1021/bi00696a011https://doi.org/10.1021/bi00696a011research-articleACS PublicationsRequest...

The lactose carrier protein of Escherichia coli was purified by a simple procedure employing differential solubilization and ion-exchange chromatography reconstituted into liposomes octylglucoside dilution. proteoliposomes exhibited both membrane potential-driven transport counterflow. Furthermore, the identified as product lac y gene. These other results demonstrate that is only polypeptide species essential for energy-coupled

Membrane vesicles isolated from E. coli generate a trans-membrane proton gradient of 2 pH units under appropriate conditions when assayed by flow dialysis. Using the distribution weak acids to measure (deltapH) and lipophilic cation triphenyl-methylphosphonium electrical potential across membrane (delta psi), are shown an electrochemical (deltamuH+) approximately-180 mV at 5.5 in presence ascorbate phenazine methosulfate, major component which is deltapH about -110mV. As external increased,...

Abstract The phosphoenolpyruvate-phosphotransferase system provides a mechanism for the passage of certain sugars through bacterial cell membrane and their accumulation as phosphorylated derivatives. These conclusions are based on following observations. 1. Isolated preparations specifically require P-enolpyruvate uptake which accumulate almost completely 2. Membranes prepared from Escherichia coli GN-2, mutant lacking Enzyme I phosphotransferase system, unable to take up significant...

Membrane Preparations-E.coli ML 308-225l (i-z-y+af) was grown on llIedium A (3) containing 1 yc disodium succinate (hesahydrate) ; E. coli 301 (i+z+y+a+) Medium 0.5yG glucuronic acid or arabinose as indicated; cola 0.5% galactose; and GN-22 (i-z+y+a+; enzyme I-) 63 (4) 0.2% glucose-6-P.Membrane vesicles were prepared from these cells described previously (5-7).Transport Studies-Assays for lactose amino uptake carried out reported (7-Q).Glucuronate, arabinose, galactose, glucose-6-P studies...

Circular dichroic measurements on the lac carrier protein purified from cytoplasmic membrane of Escherichia coli indicate that 85 f 5% amino acid residues comprising this integral are arranged in helical secondary structures.Analysis sequential hydropathic character by method Kyte and Doolittle (J.Mol.Biol.(1982) 157,105-132) indicates is composed at least 12 hydrophobic segments with a mean length 24 4 residues/segment.Approximately 70% 417 acids found these domains.The profile, together...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNADH-ubiquinone oxidoreductases of the Escherichia coli aerobic respiratory chainKazunobu Matsushita, Tomoko Ohnishi, and H. Ronald KabackCite this: Biochemistry 1987, 26, 24, 7732–7737Publication Date (Print):December 1, 1987Publication History Published online1 May 2002Published inissue 1 December 1987https://pubs.acs.org/doi/10.1021/bi00398a029https://doi.org/10.1021/bi00398a029research-articleACS PublicationsRequest reuse permissionsArticle...

By use of giant cells Escherichia coli induced by growth in the presence 6-amidinopenicillanic acid, membrane potentials have been measured two completely independent techniques: directly with intracellular microelectrodes and indirectly from steady-state distribution [3H]tetraphenylphosphonium. Under a variety conditions, methods yield values that agree very closely. Thus, both techniques, potential approximates -85 mV (interior negative) at pH 5.0 -142 8.0, an average slope -22 mV/pH unit...

Neuroblastoma-glioma hybrid cells (NG108-15) in suspension accumulate the permeant lipophilic cation [ 3 H]tetraphenylphosphonium (TPP + ) against a concentration gradient. The steady-state level of TPP accumulation is about twice as great physiological media low K (i.e., 5 mM /135 Na than medium high 121 /13.5 ). latter manipulation depolarizes NG108-15 plasma membrane and indicates that resting potential (ΔΨ) due primarily to diffusion gradient (K → out time temperature dependent,...

Here we describe an x-ray structure of wild-type lactose permease (LacY) from Escherichia coli determined by manipulating phospholipid content during crystallization. The exhibits the same global fold as previous structures a mutant that binds sugar but cannot catalyze translocation across membrane. LacY is organized into two six-helix bundles with twofold pseudosymmetry separated large interior hydrophilic cavity open only to cytoplasmic side and containing chains important for H(+)...

In the previous paper [ramos, S., and Kaback, H.R. (1977), Biochemistry 16 (preceding in this issue)], it was demonstrated that Escherichia coli membrane vesicles generate a large electrochemical proton gradient (delta-muH+) under appropriate conditions, some of properties delta-muH+ its component forces [i.e., potential (delta psi) chemical protons (deltapH)] were described. paper, relationship between delta-muH+, delta psi, deltapH active transport specific solutes is examined. Addition...

Membrane vesicles isolated from Escherichia coli grown under various conditions generate a transmembrane pH gradient (delta pH) of about 2 units (interior alkaline) appropriate when assayed by flow dialysis. Using the distribution weak acids to measure delta and lipophilic cation triphenylmethylphosphonium electrical potential psi) across membrane, are demonstrated develop an electrochemical proton (delta-muH+) almost - 200 mV negative at 5.5 in presence reduced phenazine methosulfate or...

YidC of Echerichia coli, a member the conserved Alb3/Oxa1/YidC family, is postulated to be important for biogenesis membrane proteins. Here, we use as model lactose permease (LacY), transport protein with known three-dimensional structure, determine whether plays role in polytopic insertion and/or folding. Experiments vivo and an vitro transcription/translation/insertion system demonstrate that not necessary per se, but folding LacY. By using two monoclonal antibodies directed against...

Abstract An artificial electron donor system—ascorbate and phenazine methosulfate—markedly stimulates β-galactoside transport in isolated membrane vesicles from Escherichia coli ML 308-225. Maximal rates of are dependent on the presence both ascorbate methosulfate also oxygen. Moreover, methosulfate, reduced nicotinamide adenine dinucleotide initial rate lactose transport. The effect ascorbate-phenazine is inhibited by removal oxygen or potassium cyanide, 2-heptyl-4-hydroxyquinoline-N-oxide,...

A mutant of Escherichia coli lacking phosphatidylethanolamine (PE) and a monoclonal antibody (mAb 4B1) directed against conformationally sensitive epitope (4B1) lactose permease were used to establish novel role for phospholipid in the assembly membrane protein. Epitope 4B1 is readily detectable spheroplasts right-side-out vesicles from PE-containing but not PE-deficient cells expressing permease. Lactose membranes, subjected sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis...

(1973). Membranes and Transport. CRC Critical Reviews in Microbiology: Vol. 2, No. 3, pp. 333-376.

Abstract Transport of a wide variety amino acids and sugars by membrane vesicles isolated from Escherichia coli ML 308-225 is coupled primarily to d-lactic dehydrogenase. This membrane-bound, flavin-linked primary dehydrogenase oxygen via cytochrome system also present in the vesicle membrane. Spectrophotometric evidence shows that dehydrogenase, succinic l-lactic NADH all utilize same system. There no relationship between rates oxidation electron donors respiratory chain (succinate g =...