scholarly journals A single power stroke by ATP binding drives substrate translocation in a heterodimeric ABC transporter

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Erich Stefan ◽  
Susanne Hofmann ◽  
Robert Tampé
Keyword(s):  
Abc Transporter ◽  
Antigen Processing ◽  
Atp Hydrolysis ◽  
Power Stroke ◽  
Atp Binding ◽  
Nucleotide Exchange ◽  
Single Turnover ◽  
Physiological Processes ◽  
Chemomechanical Coupling ◽  
Functional Homolog

ATP-binding cassette (ABC) transporters constitute the largest family of primary active transporters, responsible for many physiological processes and human maladies. However, the mechanism how chemical energy of ATP facilitates translocation of chemically diverse compounds across membranes is poorly understood. Here, we advance the quantitative mechanistic understanding of the heterodimeric ABC transporter TmrAB, a functional homolog of the transporter associated with antigen processing (TAP) by single-turnover analyses at single-liposome resolution. We reveal that a single conformational switch by ATP binding drives unidirectional substrate translocation. After this power stroke, ATP hydrolysis and phosphate release launch the return to the resting state, which facilitates nucleotide exchange and a new round of substrate binding and translocation. In contrast to hitherto existing steady-state assays, our single-turnover approach uncovers the power stroke in substrate translocation and the tight chemomechanical coupling in these molecular machines.

scholarly journals Theoretical Study on the ATP Hydrolysis Mechanism of HisP Protein, the ATP-Binding Subunit of ABC Transporter

2007 ◽  
Vol 48 (4) ◽  
pp. 735-739 ◽  
Author(s):  
Qiang Pei ◽  
Carlos A. Del Carpio ◽  
Hideyuki Tsuboi ◽  
Michihisa Koyama ◽  
Akira Endou ◽  
...  
Keyword(s):  
Abc Transporter ◽  
Theoretical Study ◽  
Atp Hydrolysis ◽  
Atp Binding ◽  
Hydrolysis Mechanism ◽  
Binding Subunit

Identification of a gene cluster encoding an arginine ATP-binding-cassette transporter in the genome of the thermophilic Gram-positive bacterium Geobacillus stearothermophilus strain DSMZ 13240

Microbiology ◽  
2005 ◽  
Vol 151 (3) ◽  
pp. 835-840 ◽  
Author(s):  
Rebecca Fleischer ◽  
Antje Wengner ◽  
Frank Scheffel ◽  
Heidi Landmesser ◽  
Erwin Schneider
Keyword(s):  
Amino Acids ◽  
Gene Cluster ◽  
Abc Transporter ◽  
Atp Hydrolysis ◽  
Atp Binding ◽  
Geobacillus Stearothermophilus ◽  
Positive Bacterium ◽  
Gram Positive ◽  
High Affinity ◽  
Atp Binding Cassette

A single gene cluster encoding components of a putative ATP-binding cassette (ABC) transporter for basic amino acids was identified in the incomplete genome sequence of the thermophilic Gram-positive bacterium Geobacillus stearothermophilus by blast searches. The cluster comprises three genes, and these were amplified from chromosomal DNA of G. stearothermophilus, ligated into plasmid vectors and expressed in Escherichia coli. The purified solute-binding protein (designated ArtJ) was demonstrated to bind l-arginine with high affinity (K d=0·39±0·06 μM). Competition experiments revealed only partial inhibition by excess l-lysine (38 %) and l-ornithine (46 %), while no inhibition was observed with l-histidine or other amino acids tested. The membrane-associated transport complex, composed of a permease (designated ArtM) and an ATPase component (designated ArtP), was solubilized from E. coli membranes by decanoylsucrose and purified by metal-affinity chromatography. The ArtMP complex, when incorporated into liposomes formed from a crude extract of G. stearothermophilus lipids, displayed ATPase activity in the presence of ArtJ only. Addition of l-arginine further stimulated the activity twofold. ATP hydrolysis was optimal at 60 °C and sensitive to the specific inhibitor vanadate. Analysis of kinetic parameters revealed a maximal velocity of ATP hydrolysis of 0·71 μmol Pi min−1 (mg protein)−1 and a K m (ATP) of 1·59 mM. Together, these results identify the ArtJMP complex as a high-affinity arginine ABC transporter.

scholarly journals Insect ATP-Binding Cassette (ABC) Transporters: Roles in Xenobiotic Detoxification and Bt Insecticidal Activity

2019 ◽  
Vol 20 (11) ◽  
pp. 2829 ◽  
Author(s):  
Chao Wu ◽  
Swapan Chakrabarty ◽  
Minghui Jin ◽  
Kaiyu Liu ◽  
Yutao Xiao
Keyword(s):  
Abc Transporter ◽  
Conformational Changes ◽  
Abc Transporters ◽  
Insecticidal Activity ◽  
Atp Hydrolysis ◽  
Atp Binding ◽  
Bt Toxin ◽  
Xenobiotic Detoxification ◽  
Binding Domains ◽  
Atp Binding Cassette

ATP-binding cassette (ABC) transporters, a large class of transmembrane proteins, are widely found in organisms and play an important role in the transport of xenobiotics. Insect ABC transporters are involved in insecticide detoxification and Bacillus thuringiensis (Bt) toxin perforation. The complete ABC transporter is composed of two hydrophobic transmembrane domains (TMDs) and two nucleotide binding domains (NBDs). Conformational changes that are needed for their action are mediated by ATP hydrolysis. According to the similarity among their sequences and organization of conserved ATP-binding cassette domains, insect ABC transporters have been divided into eight subfamilies (ABCA–ABCH). This review describes the functions and mechanisms of ABC transporters in insecticide detoxification, plant toxic secondary metabolites transport and insecticidal activity of Bt toxin. With improved understanding of the role and mechanisms of ABC transporter in resistance to insecticides and Bt toxins, we can identify valuable target sites for developing new strategies to control pests and manage resistance and achieve green pest control.

scholarly journals Quantitative real-time analysis of the efflux by the MacAB-TolC tripartite efflux pump clarifies the role of ATP hydrolysis within mechanotransmission mechanism

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Hager Souabni ◽  
William Batista dos Santos ◽  
Quentin Cece ◽  
Laurent J. Catoire ◽  
Dhenesh Puvanendran ◽  
...  
Keyword(s):  
High Efficiency ◽  
Atp Hydrolysis ◽  
Efflux Pump ◽  
Power Stroke ◽  
Atp Binding ◽  
Modified Model ◽  
Substrate Transport ◽  
Binding Domains ◽  
Real Time Analysis

AbstractTripartite efflux pumps built around ATP-binding cassette (ABC) transporters are membrane protein machineries that perform vectorial export of a large variety of drugs and virulence factors from Gram negative bacteria, using ATP-hydrolysis as energy source. Determining the number of ATP molecules consumed per transport cycle is essential to understanding the efficiency of substrate transport. Using a reconstituted pump in a membrane mimic environment, we show that MacAB-TolC from Escherichia coli couples substrate transport to ATP-hydrolysis with high efficiency. Contrary to the predictions of the currently prevailing “molecular bellows” model of MacB-operation, which assigns the power stroke to the ATP-binding by the nucleotide binding domains of the transporter, by utilizing a novel assay, we report clear synchronization of the substrate transfer with ATP-hydrolysis, suggesting that at least some of the power stroke for the substrate efflux is provided by ATP-hydrolysis. Our findings narrow down the window for energy consumption step that results in substrate transition into the TolC-channel, expanding the current understanding of the efflux cycle of the MacB-based tripartite assemblies. Based on that we propose a modified model of the MacB cycle within the context of tripartite complex assembly.

scholarly journals Functional Non-equivalence of ATP-binding Cassette Signature Motifs in the Transporter Associated with Antigen Processing (TAP)

2004 ◽  
Vol 279 (44) ◽  
pp. 46073-46081 ◽  
Author(s):  
Min Chen ◽  
Rupert Abele ◽  
Robert Tampé
Keyword(s):  
Antigen Processing ◽  
Transmembrane Domain ◽  
Atp Hydrolysis ◽  
Nucleotide Binding ◽  
Transport Rate ◽  
Peptide Transport ◽  
Atp Binding ◽  
Nucleotide Binding Sites ◽  
Cellular Immune ◽  
Atp Binding Cassette

The transporter associated with antigen processing (TAP) is a key component of the cellular immune system. As a member of the ATP-binding cassette (ABC) superfamily, TAP hydrolyzes ATP to energize the transport of peptides from the cytosol into the lumen of the endoplasmic reticulum. TAP is composed of TAP1 and TAP2, each containing a transmembrane domain and a nucleotide-binding domain (NBD). Here we investigated the role of the ABC signature motif (C-loop) on the functional non-equivalence of the NBDs, which contain a canonical C-loop (LSGGQ) for TAP1 and a degenerate C-loop (LAAGQ) for TAP2. Mutation of the leucine or glycine (LSGGQ) in TAP1 fully abolished peptide transport. However, TAP complexes with equivalent mutations in TAP2 still showed residual peptide transport activity. To elucidate the origin of the asymmetry of the NBDs of TAP, we further examined TAP complexes with exchanged C-loops. Strikingly, the chimera with two canonical C-loops showed the highest transport rate whereas the chimera with two degenerate C-loops had the lowest transport rate, demonstrating that the ABC signature motifs control peptide transport efficiency. All single site mutants and chimeras showed similar activities in peptide or ATP binding, implying that these mutations affect the ATPase activity of TAP. In addition, these results prove that the serine of the C-loop is not essential for TAP function but rather coordinates, together with other residues of the C-loop, the ATP hydrolysis in both nucleotide-binding sites.

scholarly journals Two-way communication between SecY and SecA suggests a Brownian ratchet mechanism for protein translocation

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
William John Allen ◽  
Robin Adam Corey ◽  
Peter Oatley ◽  
Richard Barry Sessions ◽  
Steve A Baldwin ◽  
...  
Keyword(s):  
Single Molecule ◽  
Atp Hydrolysis ◽  
Protein Translocation ◽  
Md Simulations ◽  
Atp Binding ◽  
Nucleotide Exchange ◽  
Brownian Ratchet ◽  
Ratchet Mechanism ◽  
Single Molecule Fret ◽  
Directional Movement

The essential process of protein secretion is achieved by the ubiquitous Sec machinery. In prokaryotes, the drive for translocation comes from ATP hydrolysis by the cytosolic motor-protein SecA, in concert with the proton motive force (PMF). However, the mechanism through which ATP hydrolysis by SecA is coupled to directional movement through SecYEG is unclear. Here, we combine all-atom molecular dynamics (MD) simulations with single molecule FRET and biochemical assays. We show that ATP binding by SecA causes opening of the SecY-channel at long range, while substrates at the SecY-channel entrance feed back to regulate nucleotide exchange by SecA. This two-way communication suggests a new, unifying 'Brownian ratchet' mechanism, whereby ATP binding and hydrolysis bias the direction of polypeptide diffusion. The model represents a solution to the problem of transporting inherently variable substrates such as polypeptides, and may underlie mechanisms of other motors that translocate proteins and nucleic acids.

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