In its proton-pumping photocycle, bacteriorhodopsin releases a proton to the extracellular surface at pH 7 in transition from intermediate L M. The proton-release group, named XH, was assigned low-temperature FT-IR studies single residue, E204 [Brown, L. S., Sasaki, J., Kandori, H., Maeda, A., Needleman, R., and Lanyi, J. K. (1995) Biol. Chem. 270, 27122−27126]. time-resolved room-temperature step-scan photocycle on wild-type E204Q-, E204D-mutated bacteriorhodopsin, which we present here,...

A series of novel hemes with modifications the isoprenyl side chain has been detected in archaea. Heme A(S) was isolated from cytochrome oxidases thermoacidophilic archaeon, Sulfolobus acidocaldarius. same spectroscopic features as heme but a hydroxyethylgeranylgeranyl instead hydroxyethylfarnesyl group. This variant is also present other archaeal well thermophilic eubacterium. Other archaea (Thermoplasma, Pyrobaculum) were shown to have oxidases. From these organisms, three prenylated...

A novel, improved method for purification of nitric oxide reductase (NOR) from membranes Paracoccus denitrificans has been developed. The purified enzyme is a cytochrome bc complex which, according to protein chemical and hydrodynamic data, contains two subunits in 1:1 stoichiometry. NorBC binds 0.87 g dodecyl maltoside/g forms dimer solution. Similarly, it dimeric two-dimensional crystals. Images these crystals have processed at 8 Å resolution projection the membrane. NorB subunit...

Summary Three distinct types of terminal oxidases participate in the aerobic respiratory pathways Paracoccus denitrificans. Two alternative genes encoding sub unit I aa 3 ‐type cytochrome c oxidase have been isolated before, namely ctaDI and ctaDII. Each these can be expressed separately to complement a double mutant (ActaDI, ActaDII) , indicating that they are isoforms subunit oxidase. The genomic locus quinol has isolated: cyoABC. Thisprotohaem‐containing oxidase, called bb is oniy quinoi...

We previously found that the soxABCD operon encodes a quinol oxidase complex in Sulfolobus acidocaldarius and this enzyme was purified characterized. In study, we have used cloning procedure based on conservation of sequences polymerase chain reaction to isolate new gene ( soxM ) encoding subunit another terminal oxidase. This is fusion between two central components cytochrome oxidases, subunits I III. forms transcriptional unit which expressed under heterotrophic growth conditions. The...

Summary Haem A, a prosthetic group of many respiratory oxidases, is probably synthesized from haem B (protohaem IX) in pathway which O an intermediate. Possible roles the Bacillus subtilis ctaA and CtaB gene products A synthesis were studied. Escherichia coli does not contain A. The CtaA on plasmids E. resulted accumulation membranes. presence together with increased amount found coli. was detected wild‐type B. strains. previously isolated deletion mutant to O, but ctaB mutants constructed...

Redox spectra of the haem‐copper oxidases cytochrome aa 3 Rhodobacter sphaeroides and bo Escherichia coli were recorded in visible infrared spectral regions. The reduction was initiated after light activation ‘caged electron’ donor riboflavin. Infrared redox difference exhibit absorbance changes amide I region, which are indicative very small redox‐finked conformational movements polypeptide backbone. A reproducible redox‐dependent pattern positive negative absorption is found carbonyl...

The energy-transducing mechanism of the thermoacidophilic archaebacterium Sulfolobus acidocaldarius DSM 639 has been studied, addressing question whether chemiosmotic proton gradients serve as an intermediate energy store driving F0F1-analogous ATP synthase. At pH 3.5, respiring S. cells developed electrochemical potential H+ ions, consisting mainly a gradient and small inside-negative membrane potential. steady-state motive force 140 to 160 mV was collapsed by protonophores, while...

Thermoacidophilic archaebacteria have gained much interest because of their phylogenetic distance to eubacteria and eukaryotes also unique living conditions. Investigation the energy-converting system therefore offers a key for understanding evolutionary position environmental adaptation these unusual bacteria. A plasma-membrane-associated adenosine triphosphatase with specific activities 0.3-0.6 mumol min-1 (mg protein)-1 has been detected in thermoacidophilic archaebacterium Sulfolobus...

Certain heavy metal ions such as copper and zinc serve essential cofactors of many enzymes, but are toxic at high concentrations. Thus, intracellular levels have to be subtly balanced. P-type ATPases the P(IB)-subclass play a major role in homeostasis. The thermoacidophile Sulfolobus solfataricus possesses two P(IB)-ATPases named CopA CopB. Both enzymes present cells grown copper-depleted medium accumulated upon an increase external concentration. We studied physiological roles both by...

<title>Abstract</title> Optogenetics is a method to regulate cells using light. It applied study neurons and develop diagnostic therapeutic tools for neuron-related diseases. The cation-conducting channelrhodopsin ChR2 triggers photoinduced depolarization of neuronal but generates very low ion currents due the <italic>syn</italic>-pathway its branched photocycle. In contrast, homologous anion-conducting ACR1 from <italic>Guillardia theta</italic> (<italic>Gt</italic>ACR1), exhibits high...

The plasma-membrane-associated ATPase of the thermoacidophilic archaebacterium Sulfolobus acidocaldarius characterized in a previous work [M. Lübben & G. Schäfer (1987) Eur. J. Biochem. 164, 533-540] has been solubilized. It can be easily removed from membrane by mild treatment with zwitterionic detergents, therefore it appears to peripheral protein analogous soluble F1-ATPase eubacteria and eukaryotes. Further purification achieved subsequent gel permeation ion-exchange chromatography....

The respiratory properties, cellular ATP content and absorption difference spectra of Sulfolobus acidocaldarius (DSM 639) have been investigated. In contrast to earlier postulates regarding Thermoplasma acidophilum [(1984) Syst. Appl. Microbiol. 5, 30‐40], S. seemed depend energetically on respiration‐coupled phosphorylation. Its strictly depended activity. membrane is capable proton pumping presumably contains a branched electron transport system. latter composed at least 2 types...

Summary A respiratory quinol oxidase complex that is encoded by the soxABCD operon has been purified from thermoacidophilic archaeon Sulfolobus acidocaldarius. The enzyme was solubilized with dodecyl maltoside and in presence of this detergent ethylene glycol. hydro‐dynamically homogeneous contains at least five different polypeptides. In addition to major subunits SoxA, SoxB SoxC, it two small One these translation product a short open reading frame (now called soxD gene) end operon....

P1 B -ATPases are among the most common resistance factors to metal-induced stress. Belonging superfamily of P-type ATPases, they capable exporting transition metal ions at expense adenosine triphosphate (ATP) hydrolysis. share a conserved structure three cytoplasmic domains linked by transmembrane domain. In addition, possess unique class located N-terminus. bacteria, these primarily associated with binding and either occur individually or as serial copies each other. Within this study,...

Heme-copper oxidases have two putative proton channels, the so-called K-channel and membrane-spanning D-channel. The latter contains a number of polar groups with glutamate-286 located in its center, which couldtogether bound watercontribute to transmembrane hydrogen-bonded network. Protonation states carboxyl from cytochrome bo3 Escherichia coli were studied by redox Fourier transform infrared (FTIR) difference spectroscopy. A net absorbance increase region was observed upon reduction. band...

ATPase was shown to be present on the cytoplasmic membrane of methanogenic bacterium strain Göl. The enzyme identified by an immunoelectron microscopic technique using polyclonal antiserum directed against beta subunit Escherichia coli F0F1-ATPase. Negatively stained vesicles exhibited a dense population stalked particles similar in dimensions and fine structure typical F0F1-ATPase particles.

By combining the incorporation of unnatural amino acids, click chemistry, FRET and EPR distance measurements, protein modeling biomolecular simulations, we obtained an unambiguous Ras dimer structural model disrupt by mutagenesis.

Abstract Channelrhodopsins are widely used in optogenetic applications. High photocurrents and low current inactivation levels desirable. Two parallel photocycles evoked by different retinal conformations cause cation-conducting channelrhodopsin-2 ( Cr ChR2) inactivation: one with efficient conductivity; conductivity. Given the longer half-life of conducting photocycle intermediates, which accumulate under continuous illumination, resulting a largely reduced photocurrent. Here, we...

A bacterioferritin was recently isolated from the anaerobic sulphate‐reducing bacterium Desulfovibrio desulfuricans ATCC 27774 [Romão et al. (2000) Biochemistry 39, 6841–6849]. Although its properties are in general similar to those of other bacterioferritins, it contains a haem quite distinct B, found bacterioferritins aerobic organisms. Using visible and NMR spectroscopies, as well mass spectrometry analysis, is now unambiguously identified iron‐coproporphyrin III, first example such...