Biomaterial Database

Precursor protein translocation by the Escherichia coli translocase is directed by the protonmotive force. 1992

A J Driessen

Department of Microbiology, University of Groningen, Haren, The Netherlands.

The SecY/E protein of Escherichia coli was coreconstituted with the proton pump bacteriorhodopsin and cytochrome c oxidase yielding proteoliposomes capable of sustaining a protonmotive force (delta p) of defined polarity and composition. Proteoliposomes support the ATP- and SecA-dependent translocation of proOmpA which is stimulated by a delta p, inside acid and positive. delta p of opposite polarity, inside alkaline and negative, suppresses translocation while SecA-mediated ATP hydrolysis continues unabated. delta psi and delta pH are equally effective in promoting or inhibiting translocation. Membrane-spanning translocation intermediates move backwards in the presence of a reversed delta p. These results support a model [Schiebel, E., Driessen, A.J.M., Hartl, F.-U. and Wickner, W. (1991) Cell, 64, 927-939] in which the delta p defines the direction of translocation after ATP hydrolysis has released proOmpA from its association with SecA. The polarity effect of the delta p challenges models involving delta p-dependent membrane destabilization and provides further evidence for a role of the delta p as driving force in precursor protein translocation.

UI	MeSH Term	Description	Entries
D008565	Membrane Proteins	Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.	Cell Membrane Protein,Cell Membrane Proteins,Cell Surface Protein,Cell Surface Proteins,Integral Membrane Proteins,Membrane-Associated Protein,Surface Protein,Surface Proteins,Integral Membrane Protein,Membrane Protein,Membrane-Associated Proteins,Membrane Associated Protein,Membrane Associated Proteins,Membrane Protein, Cell,Membrane Protein, Integral,Membrane Proteins, Integral,Protein, Cell Membrane,Protein, Cell Surface,Protein, Integral Membrane,Protein, Membrane,Protein, Membrane-Associated,Protein, Surface,Proteins, Cell Membrane,Proteins, Cell Surface,Proteins, Integral Membrane,Proteins, Membrane,Proteins, Membrane-Associated,Proteins, Surface,Surface Protein, Cell
D008715	Methionine	A sulfur-containing essential L-amino acid that is important in many body functions.	L-Methionine,Liquimeth,Methionine, L-Isomer,Pedameth,L-Isomer Methionine,Methionine, L Isomer
D011498	Protein Precursors		Precursors, Protein
D011522	Protons	Stable elementary particles having the smallest known positive charge, found in the nuclei of all elements. The proton mass is less than that of a neutron. A proton is the nucleus of the light hydrogen atom, i.e., the hydrogen ion.	Hydrogen Ions,Hydrogen Ion,Ion, Hydrogen,Ions, Hydrogen,Proton
D004926	Escherichia coli	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.	Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D006868	Hydrolysis	The process of cleaving a chemical compound by the addition of a molecule of water.
D000069816	SEC Translocation Channels	Universally conserved multiprotein complexes that form the protein transport channel of the general secretory (SEC) pathway. The SEC translocase is present in all bacteria, archaea, and eukaryotes. It is in the ENDOPLASMIC RETICULUM membrane of eukaryotic cells, in the THYLAKOID MEMBRANE in CHLOROPLASTS and in some protozoa in the INNER MITOCHONDRIAL MEMBRANE.	SEC Translocation Channel,SEC Translocon,SEC61 Translocation Channel,Sec Protein Translocation System,SecYEG Protein,SecYEG Translocation Channel,SEC Complexes,SEC Translocase,SEC Translocons,SEC61 Protein,SEC61 Proteins,SEC61 Translocase,SEC61 Translocation Channels,SEC61 Translocon,Sec Protein Translocation Systems,Sec61 Complex,Sec61 Protein Translocation System,SecY Translocase,SecYEG Complex,SecYEG Complexes,SecYEG Protein Translocation System,SecYEG Proteins,SecYEG Translocation Channels,SecYEG Translocon,Channel, SEC Translocation,Channel, SEC61 Translocation,Channel, SecYEG Translocation,Channels, SEC Translocation,Channels, SEC61 Translocation,Channels, SecYEG Translocation,Complex, Sec61,Complex, SecYEG,Complexes, SEC,Complexes, SecYEG,Protein, SEC61,Protein, SecYEG,Proteins, SEC61,Proteins, SecYEG,Translocase, SEC,Translocase, SEC61,Translocase, SecY,Translocation Channel, SEC,Translocation Channel, SEC61,Translocation Channel, SecYEG,Translocation Channels, SEC,Translocation Channels, SEC61,Translocation Channels, SecYEG,Translocon, SEC,Translocon, SEC61,Translocon, SecYEG,Translocons, SEC
D000081416	SecA Proteins	ATPases that provide energy for the translocation of proteins across bacterial PLASMA MEMBRANES and THYLAKOID membranes, by the SEC TRANSLOCATION CHANNELS. SecA is a component of the bacterial preprotein translocase which is comprised of SecA, the SECYEG TRANSLOCON, and the accessory domain proteins SecD, SecF, YajC, and YidC.	SecA Protein,Protein, SecA,Proteins, SecA
D000251	Adenosine Triphosphatases	A group of enzymes which catalyze the hydrolysis of ATP. The hydrolysis reaction is usually coupled with another function such as transporting Ca(2+) across a membrane. These enzymes may be dependent on Ca(2+), Mg(2+), anions, H+, or DNA.	ATPases,Adenosinetriphosphatase,ATPase,ATPase, DNA-Dependent,Adenosine Triphosphatase,DNA-Dependent ATPase,DNA-Dependent Adenosinetriphosphatases,ATPase, DNA Dependent,Adenosinetriphosphatases, DNA-Dependent,DNA Dependent ATPase,DNA Dependent Adenosinetriphosphatases,Triphosphatase, Adenosine