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Full-Text Articles in Life Sciences

The Proton-Translocating A Subunit Of F0f1-Atp Synthase Is Allocated Asymmetrically To The Peripheral Stalk., Monika G Düser, Yumin Bi, Nawid Zarrabi, Stanley D Dunn, Michael Börsch Nov 2008

The Proton-Translocating A Subunit Of F0f1-Atp Synthase Is Allocated Asymmetrically To The Peripheral Stalk., Monika G Düser, Yumin Bi, Nawid Zarrabi, Stanley D Dunn, Michael Börsch

Biochemistry Publications

The position of the a subunit of the membrane-integral F0 sector of Escherichia coli ATP synthase was investigated by single molecule fluorescence resonance energy transfer studies utilizing a fusion of enhanced green fluorescent protein to the C terminus of the a subunit and fluorescent labels attached to specific positions of the epsilon or gamma subunits. Three fluorescence resonance energy transfer levels were observed during rotation driven by ATP hydrolysis corresponding to the three resting positions of the rotor subunits, gamma or epsilon, relative to the a subunit of the stator. Comparison of these positions of the rotor sites with those …


Domain Compliance And Elastic Power Transmission In Rotary F(O)F(1)-Atpase., Hendrik Sielaff, Henning Rennekamp, André Wächter, Hao Xie, Florian Hilbers, Katrin Feldbauer, Stanley D Dunn, Siegfried Engelbrecht, Wolfgang Junge Nov 2008

Domain Compliance And Elastic Power Transmission In Rotary F(O)F(1)-Atpase., Hendrik Sielaff, Henning Rennekamp, André Wächter, Hao Xie, Florian Hilbers, Katrin Feldbauer, Stanley D Dunn, Siegfried Engelbrecht, Wolfgang Junge

Biochemistry Publications

The 2 nanomotors of rotary ATP synthase, ionmotive F(O) and chemically active F(1), are mechanically coupled by a central rotor and an eccentric bearing. Both motors rotate, with 3 steps in F(1) and 10-15 in F(O). Simulation by statistical mechanics has revealed that an elastic power transmission is required for a high rate of coupled turnover. Here, we investigate the distribution in the F(O)F(1) structure of compliant and stiff domains. The compliance of certain domains was restricted by engineered disulfide bridges between rotor and stator, and the torsional stiffness (kappa) of unrestricted domains was determined by analyzing their thermal rotary …


Tethering Polypeptides Through Bifunctional Peg Cross-Linking Agents To Probe Protein Function: Application To Atp Synthase., Daniel J Cipriano, Stanley D Dunn Nov 2008

Tethering Polypeptides Through Bifunctional Peg Cross-Linking Agents To Probe Protein Function: Application To Atp Synthase., Daniel J Cipriano, Stanley D Dunn

Biochemistry Publications

Chemical crosslinking mediated by short bifunctional reagents has been widely used for determining physical relationships among polypeptides in multisubunit proteins, but less often for functional studies. Here we introduce the approach of tethering polypeptides by using bifunctional reagents containing a lengthy, flexible PEG linker as a form of crosslinking especially suited to functional analyses. The rotary molecular motor ATP synthase was used as a model subject. Single cysteine residues were introduced into selected positions of ATP synthase epsilon subunit, a component of the rotor subcomplex of the enzyme, and the unrelated maltose binding protein (MBP), then the two purified recombinant …


Probing The Functional Tolerance Of The B Subunit Of Escherichia Coli Atp Synthase For Sequence Manipulation Through A Chimera Approach., Yumin Bi, Joel C Watts, Pamela Krauss Bamford, Lee-Ann K Briere, Stanley D Dunn Jul 2008

Probing The Functional Tolerance Of The B Subunit Of Escherichia Coli Atp Synthase For Sequence Manipulation Through A Chimera Approach., Yumin Bi, Joel C Watts, Pamela Krauss Bamford, Lee-Ann K Briere, Stanley D Dunn

Biochemistry Publications

A dimer of 156-residue b subunits forms the peripheral stator stalk of eubacterial ATP synthase. Dimerization is mediated by a sequence with an unusual 11-residue (hendecad) repeat pattern, implying a right-handed coiled coil structure. We investigated the potential for producing functional chimeras in the b subunit of Escherichia coli ATP synthase by replacing parts of its sequence with corresponding regions of the b subunits from other eubacteria, sequences from other polypeptides having similar hendecad patterns, and sequences forming left-handed coiled coils. Replacement of positions 55-110 with corresponding sequences from Bacillus subtilis and Thermotoga maritima b subunits resulted in fully functional …


Crystal Structures Of The Streptomyces Coelicolor Tetr-Like Protein Actr Alone And In Complex With Actinorhodin Or The Actinorhodin Biosynthetic Precursor (S)-Dnpa., A R Willems, K Tahlan, T Taguchi, K Zhang, Z Z Lee, K Ichinose, M S Junop, J R Nodwell Mar 2008

Crystal Structures Of The Streptomyces Coelicolor Tetr-Like Protein Actr Alone And In Complex With Actinorhodin Or The Actinorhodin Biosynthetic Precursor (S)-Dnpa., A R Willems, K Tahlan, T Taguchi, K Zhang, Z Z Lee, K Ichinose, M S Junop, J R Nodwell

Biochemistry Publications

Actinorhodin, an antibiotic produced by Streptomyces coelicolor, is exported from the cell by the ActA efflux pump. actA is divergently transcribed from actR, which encodes a TetR-like transcriptional repressor. We showed previously that ActR represses transcription by binding to an operator from the actA/actR intergenic region. Importantly, actinorhodin itself or various actinorhodin biosynthetic intermediates can cause ActR to dissociate from its operator, leading to derepression. This suggests that ActR may mediate timely self-resistance to an endogenously produced antibiotic by responding to one of its biosynthetic precursors. Here, we report the structural basis for this precursor-mediated derepression with crystal structures of …


The Stator Complex Of The A1a0-Atp Synthase--Structural Characterization Of The E And H Subunits., Erik Kish-Trier, Lee-Ann K Briere, Stanley D Dunn, Stephan Wilkens Jan 2008

The Stator Complex Of The A1a0-Atp Synthase--Structural Characterization Of The E And H Subunits., Erik Kish-Trier, Lee-Ann K Briere, Stanley D Dunn, Stephan Wilkens

Biochemistry Publications

Archaeal ATP synthase (A-ATPase) is the functional homolog to the ATP synthase found in bacteria, mitochondria and chloroplasts, but the enzyme is structurally more related to the proton-pumping vacuolar ATPase found in the endomembrane system of eukaryotes. We have cloned, overexpressed and characterized the stator-forming subunits E and H of the A-ATPase from the thermoacidophilic Archaeon, Thermoplasma acidophilum. Size exclusion chromatography, CD, matrix-assisted laser desorption ionization time-of-flight mass spectrometry and NMR spectroscopic experiments indicate that both polypeptides have a tendency to form dimers and higher oligomers in solution. However, when expressed together or reconstituted, the two individual polypeptides interact with …