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PubMed1994

Interspecific transfer of mitochondrial genes in fungi and creation of a homologous hybrid gene.

In eukaryotes, horizontal gene transfer is a rare event. Here we show that the mitochondrial genome of a lower fungus, Allomyces macrogynus, has an extra DNA segment not present in a close relative, Allomyces arbusculus. This insert consists of the C terminus of a foreign gene encoding a subunit of the ATP synthetase complex (atp6) plus an open reading frame encoding an endonuclease. The inserted atp6 portion is fused in phase to the resident gene, resulting in expression of a hybrid atp6 gene and the displacement of the original C-terminal atp6 region. We present evidence that this insertion may have been acquired by interspecific transfer and we discuss the possible role of the endonuclease in this process.

Amino Acid Sequence↗
PubMed1991

[Age-related differences in the effect of osmotic pressure on liver mitochondrial respiration in rats].

The subject under investigation is the influence of osmotic pressure of incubation medium (25-500 mM of sucrose) upon the respiration and the respiration control (RC) of mitochondria of the liver of rats aged 1, 3, 12 and 24 months when oxidizing succinate. In a medium with 0.3 M of sucrose the respiration rate under condition 3 (V3) and RC increased from the age of 1 to 12 months and decreased by 24 months. In a medium with 0.15 M of sucrose the age differences have not been observed. In a uncoupling state the osmotic dependence of the respiration of mitochondria of 1- and 12-month-old rats did not vary. It is assumed that with age there is a change in the rate of structural coupling of the carrier of adenine nucleotides with H(+)-ATP synthetase complex and (or) the viscosity of the matrix.

Aging↗
PubMed1987

[Effect of a number of biologically active substances on the activity of membrane-bound Na+,K+-ATPase from the bovine brain].

Cellular Na+, K+-transport ATPase appears to be more resistant to the influence of DNA intercalators and other agents than ATP-synthetase complex of inner mitochondrial membrane. Neither synthetic intercalators, nor antibiotics olivomycin and actinomycin D, some uncouplers of oxidative phosphorylation, alkaloids and inorganic bivalent cations selectively (up to 10(-4) M) inhibit Na+, K+-ATPase activity. Besides ouabain, alkaloid sanguinarine and cation Ag+ (the latter in the absence of anion Cl-) cause a significant decrease of Na+, K+-ATPase activity. Ag+ is most potent as inhibitor, while sanguinarine is weaker than ouabain. Inhibition of Na+, K+-ATPase by sanguinarine may result presumably from modification of SH-groups of the enzyme.

Alkaloids↗
PubMed1993

[Rotenone-sensitive oxidation of NADH and F0F1-ATPase activity in a homogenate of rat skeletal muscles during thermal adaptation].

A method has been developed for measuring the rates of rotenone-sensitive oxidation of NADH and oligomycin-sensitive hydrolysis of ATP in rat skeletal muscle homogenates. The method is based on the use of alamethicin which increases the permeability of the inner mitochondrial membrane for NADH and ATP. It has been shown that prolonged cold adaptation of rats (4 weeks, 4 degrees) does not change the activity of rotenone-sensitive NADH-oxidase in rat skeletal muscle homogenates which is equal to 12.4 +/- 4.4 nmol NADH/min/mg protein, but increases threefold that of F0F1-ATPase--from 31.8 +/- 7.4 up to 93.1 +/- 14.3 nmol P(i)/min/mg protein. It is suggested that prolonged cold adaptation induces structural-and-functional changes in the H(+)-ATP-synthetase complex of skeletal muscle mitochondria.

Adaptation, Physiological↗
PubMed1985

Functional changes in mitochondrial properties as a result of their membrane cryodestruction. II. Influence of freezing and thawing on ATP complex activity of intact liver mitochondria.

The influence of the freeze-thawing rates on ATP synthetase (ATPase) complex of intact liver mitochondria was investigated. It was shown that the increase in latent ATPase activity and decrease in ATP synthetase activity resulted from an influence on the inner mitochondrial membrane. An increase in freeze-thawing rates led to the preservation of ATP synthetase activity and ATP hydrolysis reduction. Kinetic parameter changes of the ATP synthetase reaction resulted from an insignificant nonspecific increase in the inner mitochondrial membrane permeability and changes in its electrochemical potential level.

ATP Synthetase Complexes↗
PubMed1989

Structure of E. coli glutaminyl-tRNA synthetase complexed with tRNA(Gln) and ATP at 2.8 A resolution.

The crystal structure of Escherichia coli glutaminyl-tRNA synthetase (GlnRS) complexed with its cognate glutaminyl transfer RNA (tRNA(Gln] and adenosine triphosphate (ATP) has been derived from a 2.8 angstrom resolution electron density map and the known protein and tRNA sequences. The 63.4-kilodalton monomeric enzyme consists of four domains arranged to give an elongated molecule with an axial ratio greater than 3 to 1. Its interactions with the tRNA extend from the anticodon to the acceptor stem along the entire inside of the L of the tRNA. The complexed tRNA retains the overall conformation of the yeast phenylalanine tRNA (tRNA(Phe] with two major differences: the 3' acceptor strand of tRNA(Gln) makes a hairpin turn toward the inside of the L, with the disruption of the final base pair of the acceptor stem, and the anticodon loop adopts a conformation not seen in any of the previously determined tRNA structures. Specific recognition elements identified so far include (i) enzyme contacts with the 2-amino groups of guanine via the tRNA minor groove in the acceptor stem at G2 and G3; (ii) interactions between the enzyme and the anticodon nucleotides; and (iii) the ability of the nucleotides G73 and U1.A72 of the cognate tRNA to assume a conformation stabilized by the protein at a lower free energy cost than noncognate sequences. The central domain of this synthetase binds ATP, glutamine, and the acceptor end of the tRNA as well as making specific interactions with the acceptor stem.2+t is

Adenosine Triphosphate↗
PubMed1984

Identification and partial DNA sequence of the gene for the alpha-subunit of the ATP synthase complex of Chlamydomonas reinhardii chloroplasts.

The partial DNA sequences of two unidentified genes flanking the gene for the large subunit of ribulose bisphosphate carboxylase of Chlamydomonas reinhardii have been reported [(1982) J. Mol. Biol. 162, 775-793]. Based on a comparison of the derived amino acid sequence of one of these genes with the corresponding sequences from Nicotiana tabacum chloroplast DNA and the E. coli atp (unc) operon, one Chlamydomonas gene is identified as coding for the alpha-subunit of the ATP synthase complex.

ATP Synthetase Complexes↗
PubMed1996

Crystal structures of three misacylating mutants of Escherichia coli glutaminyl-tRNA synthetase complexed with tRNA(Gln) and ATP.

Three previously described mutant Escherichia coli glutaminyl-tRNA synthetase (GlnRS) proteins that incorrectly aminoacylate the amber suppressor derived from tRNATyr (supF) with glutamine were cocrystallized with wild-type tRNAGln and their structures determined. In two of the mutant enzymes studied, Asp235, which contacts base pair G3-C70 in the acceptor stem, has been changed to asparagine in GlnRS7 and to glycine in GlnRS10. These mutations result in changed interactions between Asn235 of GlnRS7 and G3-C70 of the tRNA and an altered water structure between Gly235 of GlnRS10 and base pair G3-C70. These structures suggest how the mutant enzymes can show only small changes in their ability to aminoacylate wild-type cognate tRNA on the one hand and yet show a lack of discrimination against a noncognate U3-A70 base pair on the other. In contrast, the change of Ile129 to Thr in GlnRS15 causes virtually no change in the structure of the complex, and the explanation for its ability to misacylate supF is unclear.

Acylation↗
PubMed1984

Subunit b of the membrane moiety (F0) of ATP synthase (F1F0) from Escherichia coli is indispensable for H+ translocation and binding of the water-soluble F1 moiety.

The ATP synthase complex, designated F1F0, of Escherichia coli is composed of a water-soluble portion (F1; membrane-associated ATPase, EC 3.6.1.3) with ATP-hydrolyzing activity and a membrane-integrated part (F0) with H+-translocating activity. F0 is built up from three kinds of subunits (a, b, and c). We have isolated the F0 portion directly from membranes of an E. coli strain (KY 7485) that overproduces the enzyme several fold. Subunit b was extracted from purified F0 by two methods. One method included prolonged incubation of the F0 complex in the presence of trichloroacetate (2.5 M) and the separation of subunit b and an a-c complex by gel filtration. Alternatively, subunit b was extracted by deoxycholate and separated from the a-c complex by hydrophobic-interaction chromatography. Integrated into liposomes, the a-c complex exhibited neither H+ uptake nor binding of F1. However, a functional F0 complex was reconstituted by adding stoichiometric amounts of subunit b to the a-c complex.

ATP Synthetase Complexes↗
PubMed1980

Proton efflux through the chloroplast ATP synthase (CF0 . CF1) in the presence of sulfhydryl-modifying agents.

The rate of photosynthetic electron transport measured in the absence of ADP and Pi is stimulated by low levels of Hg2+ or Ag+ (50% stimulation approximately or equal to 3 Hg2+ or 6 Ag+/100 chlorophyll) to a plateau equal to the transport rate under normal phosphorylating conditions (i.e. +ADP, +Pi). Chloroplasts pretreated in the light under energizing conditions with N-ethylmaleimide show a similar stimulation of non-phosphorylating electron transport. The stimulations of non-phosphorylating electron transport by Hg2+, Ag+ and N-ethylmaleimide are reversed by the CF1 inhibitor phlorizin, the CF0 inhibitor triphenyltin chloride, and can be further stimulated by uncouplers such as methylamine. The Hg2+ and N-ethylmalemide stimulations, but not the Ag+ stimulation, are completely reversed by low levels of ADP (2 microM), ATP (2 microM), AND Pi (400 microM). Ag+, which is a potent inhibitor of ATP synthesis, has little or no effect upon phosphorylating electron transport (+ADP, +Pi). Concomitant with the stimulations of non-phosphorylating electron transport by Hg2+, Ag+ and ADP + Pi, there is a decrease in the level of membrane energization (as measured by atebrin fluorescence quenching) which is reversed when the CF0 channel is blocked by triphenyltin. These results suggest that modification of critical CF1 sulfhydryl residues by Hg2+, Ag+ or N-ethylmalemide leads to the loss of intra-enzyme coupling between the transmembrane proton-transferring and the ATP synthesis activities of the CF0-CF1 ATP synthase complex.

ATP Synthetase Complexes↗
PubMed1985

Analyses of muscle proteins in a patient with a mitochondrial myopathy.

Using the small amounts of muscle available from biopsy (approximately 100 mg), from both normal controls and a patient with a previously identified defect of the mitochondrial electron transfer protein complex III, we analyzed both structural and mitochondrial proteins. The myosin light chains were found to be unchanged with respect to charge or size between patient and control. Two prominent proteins detected after two dimensional gel electrophoresis were present in the patient's total homogenised muscle protein but were not detected in the controls. One protein was positively identified as cytochrome c oxidase subunit II and the other tentatively as a component of the ATP synthetase. We suggest that the increased amounts of these proteins represents a response of the patients muscle cells to the ATP deficiency caused by the primary lesion in complex III.

ATP Synthetase Complexes↗
PubMed2003

The proton channel is the minimal structure of ATP synthase necessary and sufficient for microcin h47 antibiotic action.

It had been previously determined that the presence of F(o)F(1) ATP synthase was required for microcin H47 antibiotic action. In this work, microcin-resistant atp mutants were genetically analyzed. Their mutations, originated by Tn5 insertion, in all cases were found to affect determinants for the F(o) portion of ATP synthase. To discern if microcin action required the presence of the entire complex or if the F(o) proton channel would suffice, recombinant plasmids carrying different segments of the atp operon were constructed and introduced into an atp deletion strain. The phenotypic analysis of the strains thus obtained clearly indicated that the presence of the F(o) proton channel was absolutely required for microcin H47 action, while the F(1) catalytic portion was found to be dispensable. Furthermore, when any of the three components of the proton channel was missing, total resistance to the antibiotic ensued. Complementation analysis between atp::Tn5 chromosomal mutations and recombinant atp plasmid constructions further supported the idea that the proton channel would be the minimal structure of the ATP synthase complex needed for microcin H47 antibiotic action.

ATP Synthetase Complexes↗
PubMed1997

The ovine model of neuronal ceroid lipofuscinosis (NCL): its contribution to understanding the pathogenesis of Batten disease.

Development of the ovine model of NCL has been pivotal to our present understanding of the ceroid lipofuscinoses. Analyses of isolated storage product have shown it to be composed of identifiable chemical species of which subunit c of mitochondrial ATP synthase is dominant (ca 50%). It is an extremely hydrophobic protein and failure to catabolise it may be associated with a propensity to form paracrystalline structures with lipids that cannot be degraded by the normal complement of lysosomal enzymes. However, the putative biochemical defect must be related to it and may reside within the mitochondria. Multiple copies of subunit c help form the transmembrane Fo complex which, with partially immobilised lipids, forms an Fo complex domain. This may need to be disassembled in an orderly fashion before proteolysis of subunit c can occur. It is postulated that the primary defect may involve disassembly of the Fo complex domain which may involve more than one step.

ATP Synthetase Complexes↗
PubMed1983

The amino acid sequence of the beta-subunit of ATP synthase from bovine heart mitochondria.

The amino acid sequence of the beta-subunit of bovine heart mitochondrial ATP synthase has been determined by protein sequence analysis. The polypeptide chain of 478 amino acids is blocked at its NH2 terminal. Comparison of this sequence with sequences of the corresponding proteins from Escherichia coli (Saraste, M., Gay, N.J., Eberle, A., Runswick, M.J., and Walker, J.E. (1981) Nucleic Acids Res. 9, 5287-5296) and maize and spinach chloroplasts Krebbers, E.T., Larrinua, I. M., McIntosh, L., and Bogorad, L. (1982) Nucleic Acids Res. 10, 4985-5002; Kurawski, G., Bottomley, W., and Whitfield, P.R. (1982) Proc. Natl. Acad. Sci. U.S.A. 79, 6260-6264) shows that the protein is highly conserved. 70% of residues are identical in E. coli and beef mitochondria. This contrasts with some of the other subunits in the enzyme complex which are much less conserved.

ATP Synthetase Complexes↗
PubMed1993

A transcription map of the chloroplast genome from rice (Oryza sativa).

The complete nucleotide sequence (134,525 bp) of the chloroplast genome from rice (Oryza sativa L.) contains four rRNA genes, 30 tRNA genes, and over 100 genes that encode proteins. However, expression of only a few of these genes, namely psbA, rbcL, and atpB/E, has been detected. We constructed the complete transcription map of rice chloroplast DNA by Northern hybridization of total RNA from rice seedlings, using subclones from a clone bank of rice chloroplast DNA as probes. Approximately 90% of the chloroplast genome was transcribed, as detected by a non-radioactive hybridization system. Most of the genes on the chloroplast DNA are organized as clusters and are co-transcribed as long primary transcripts. We identified 16 polycistronic transcripts from the rice chloroplast genome. Furthermore, the genes for components of photosystems I and II, the gene for the large subunit of RuBisCO, the genes for ATPase, the genes for components of the cytochrome complex, and the rRNA genes were expressed at the highest levels.

ATP Synthetase Complexes↗
PubMed2000

Organisation of the yeast ATP synthase F(0):a study based on cysteine mutants, thiol modification and cross-linking reagents.

A topological study of the yeast ATP synthase membranous domain was undertaken by means of chemical modifications and cross-linking experiments on the wild-type complex and on mutated enzymes obtained by site-directed mutagenesis of genes encoding ATP synthase subunits. The modification by non-permeant maleimide reagents of the Cys-54 of mutated subunit 4 (subunit b), of the Cys-23 in the N-terminus of subunit 6 (subunit a) and of the Cys-91 in the C-terminus of mutated subunit f demonstrated their location in the mitochondrial intermembrane space. Near-neighbour relationships between subunits of the complex were demonstrated by means of homobifunctional and heterobifunctional reagents. Our data suggest interactions between the first transmembranous alpha-helix of subunit 6, the two hydrophobic segments of subunit 4 and the unique membrane-spanning segments of subunits i and f. The amino acid residue 174 of subunit 4 is close to both oscp and the beta-subunit, and the residue 209 is close to oscp. The dimerisation of subunit 4 in the membrane revealed that this component is located in the periphery of the enzyme and interacts with other ATP synthase complexes.

ATP Synthetase Complexes↗