Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nucleotides have at least two functions in eukaryotic cilia and flagella. ATP, originating in the cells, is utilized for motility by energy-transducing protein(s) called dynein, and the binding of guanine nucleotides to tubulin, and probably certain transformations of the bound nucleotides, are prerequisites for the assembly of microtubules. Besides dynein, which can be solubulized from Chlamydomonas flagella as a heterogeneous, Mg2+ or Ca2+-activated ATPase, we have purified and characterized five other flagellar enzymes involved in nucleotide transformations. A homogeneous, low molecular weight, Ca2+-specific adenosine triphosphatase was isolated, which was inhibited by Mg2+ and was not specific for ATP. This enzyme was not formed by treating purified dynein with proteases. It was absent from extracts of Tetrahymena cilia. Its function might be an auxiliary energy transducer, or in steering or tactic responses. Two species of adenylate kinase were isolated, one of which was much elevated in regenerating flagella; the latter was also present in cell bodies. A large part of flagellar nucleoside diphosphokinase activity could not be solubilized. Two soluble enzyme species were identified, one of which was also present in cell bodies. Since these enzymes are of interest because they might function in microtubule assembly, we studied the extent to which brain nucleoside diphosphokinase co-polymerizes with tubulin purified by repeated cycles of polymerization. Arginine kinase was not detected in Chlamydomonas flagellar extracts.
...
PMID:Nucleotide-metabolizing enzymes in Chlamydomonas flagella. 0 Mar 97

Dynein isolated from Chlamydomonas flagellar axonemes binds to microtubules assembled in vitro from 6S brain tubulin dimers. The dynein arms bind periodically along the length of the microtubules with a center-to-center spacing of 24 nm, equal to the periodicity of dynein arms on intact axonemes. The arms project from the in vitro assembled microtubules at an angle of approximately 55 degrees, thereby defining microtubule polarity. Dynein cosediments with microtubules through a sucrose gradient, as demonstrated by electron microscopy, gel electrophoresis, and ATPase analysis. In addition, dynein induces crossbridging between adjacent microtubules. Darkfield microscopy reveals that microtubules containing dynein are aggregated into large bundles; electron microscopy indicates that microtubules of the same polarity are crossbridged by a regular array of arms. Viewed by darkfield microscopy, addition of ATP to crossbridged microtubules causes their disaggregation; electron microscopy shows that the majority of these microtubules are no longer crossbridged. These observations are applicable to the determination of microtubule polarity and directionality of microtubule assembly in situ and suggest a role for dynein in cytoplasmic microtubule-based cellular movements.
...
PMID:Dynein binds to and crossbridges cytoplasmic microtubules. 16 May 55

We have analyzed extragenic suppressors of paralyzed flagella mutations in Chlamydomonas reinhardtii in an effort to identify new dynein mutations. A temperature-sensitive allele of the PF16 locus was mutagenized and then screened for revertants that could swim at the restrictive temperature (Dutcher et al. 1984. J. Cell Biol. 98:229-236). In backcrosses of one of the revertant strains to wild-type, we recovered both the original pf16 mutation and a second, unlinked suppressor mutation with its own flagellar phenotype. This mutation has been identified by both recombination and complementation tests as a new allele of the previously uncharacterized PF9 locus on linkage group XII/XIII. SDS-PAGE analysis of isolated flagellar axonemes and dynein extracts has demonstrated that the pf9 strains are missing four polypeptides that form the I1 inner arm dynein subunit. The primary effect of the loss of the I1 subunit is a decrease in the forward swimming velocity due to a change in the flagellar waveform. Both the flagellar beat frequency and the axonemal ATPase activity are nearly wild-type. Examination of axonemes by thin section electron microscopy and image averaging methods reveals that a specific domain of the inner arm complex is missing in the pf9 mutant strains (see accompanying paper by Mastronarde et al.). When combined with other flagellar defects, the loss of the I1 subunit has synergistic effects on both flagellar assembly and flagellar motility. These synthetic phenotypes provide a screen for new suppressor mutations in other loci. Using this approach, we have identified the first interactive suppressors of a dynein arm mutation and an unusual bypass suppressor mutation.
...
PMID:Extragenic suppressors of paralyzed flagellar mutations in Chlamydomonas reinhardtii identify loci that alter the inner dynein arms. 138 4

Tentoxin is a naturally occurring phytotoxic peptide that causes seedling chlorosis and arrests growth in sensitive plants and algae. In vitro, it inhibits activity of the beta subunit of the plastid proton-adenosine triphosphatase (ATPase) from sensitive species. Plastid atpB genes from six closely related, tentoxin-sensitive or -resistant Nicotiana species differ at codon 83, according to their response to the toxin: glutamate correlated with resistance and aspartate correlated with sensitivity. The genetic relevance of this site was confirmed in Chlamydomonas reinhardtii by chloroplast transformation. The alga, normally tentoxin-resistant, was rendered tentoxin-sensitive by mutagenesis of its plastid atpB gene at codon 83. Codon 83 may represent a critical site on the beta subunit that does not compete with nucleotide binding or other catalytic activities.
...
PMID:Tentoxin sensitivity of chloroplasts determined by codon 83 of beta subunit of proton-ATPase. 138 30

Outer-arm dynein purified from trout spermatozoa was disrupted by low-ionic-strength dialysis, and the resulting subunits were separated by sucrose density-gradient centrifugation. The intact 19 S dynein, containing the alpha- an beta-heavy chains, intermediate chains (ICs) 1-5 and light chains (LCs) 1-6, yielded several discrete particles: a 17.5 S adenosine triphosphatase (ATPase) composed of the alpha- and beta-chains ICs 3-5 and LC 1; a 9.5 S complex containing ICs 1 and 2 together with LCs 2, 3, 4, and 6; and a single light chain (LC 5), which sedimented at approximately 4 S. In some experiments, ICs 3-5 also separated from the heavy chain complex and were obtained as a distinct subunit. Further dissociation of the 17.5 S particle yielded a 13.1 S ATPase that contained the beta-heavy chain and ICs 3-5. The polypeptide compositions of the complexes provide new information on the intermolecular associations that occur within dynein. Substructural features of the trout dynein polypeptides also were examined. The heavy chains were subjected to vanadate-mediated photolysis at the V1 sites by irradiation at 365 nm in the presence of Mg2+, ATP, and vanadate. Fragment pairs of relative molecular mass (Mr) 245,000/185,000 and 245,000/170,000 were obtained from the alpha- and beta-heavy chains, respectively. Photolysis of these molecules at their V2 sites, by irradiation in the presence of vanadate and Mn2+, yielded fragments of Mr 160,000/270,000 and 165,000/250,000, respectively. These values confirm that the alpha- and beta-heavy chains have masses of 430,000 and 415,000 daltons, respectively. Immunological analysis using monoclonal antibodies revealed that one intermediate chain from trout dynein (IC 2) contains epitopes present in two different intermediate chains from Chlamydomonas dynein. This indicates that specific sequences within the dynein intermediate chains have been highly conserved throughout evolution.
...
PMID:Outer-arm dynein from trout spermatozoa: substructural organization. 169 10

The Chlamydomonas reinhardtii chloroplast atpB mRNA contains sequences at its 3' end that can form a complex stem/loop structure. Deletions of part or all of this sequence in transformed C. reinhardtii cells led to decreased atpB mRNA accumulation, whereas transcription rates were unaffected. The reduction of mRNA to 20% to 35% of wild-type levels in transformants without 3' stem/loops was correlated with the accumulation of atpB mRNA that was heterogeneous in size. These results indicated that RNA secondary structures function both in mRNA stabilization and in 3' end formation in C. reinhardtii chloroplasts. Furthermore, deletion of the stem/loop resulted in a decrease in the steady-state level of the ATPase beta-subunit to approximately 60% of wild-type levels, suggesting that translational and/or post-translational mechanisms may influence the steady-state level of the atpB gene product.
...
PMID:A 3' stem/loop structure of the Chlamydomonas chloroplast atpB gene regulates mRNA accumulation in vivo. 184 Sep 11

The ATPase activities in Chlamydomonas axonemes were compared between wild type and a mutant (oda) that lacks entire outer dynein arms, at various ionic strengths and pH values, and in the presence of different concentrations of high-molecular-mass dextran. Over a 0-0.2 M KCl concentration range, the ATPase activity of oda axonemes was found to be 5-12 times lower than that of the wild-type axonemes. The low activity in oda is surprising since outer arm-depleted axonemes of sea urchin sperm have been reported to retain about 50% of the normal activity. In both wild type and oda, the ATPase activity of dynein was higher when contained within the axoneme than when released from it with 0.6 M KCl. The ATPase activation within the wild-type axoneme was inhibited by high ionic strengths or by the presence of dextran. The activation in oda axonemes, on the other hand, was not inhibited by these factors. These significantly different ATPase properties suggest that the inner and outer dynein arms perform somewhat different functions in this organism.
...
PMID:Strikingly low ATPase activities in flagellar axonemes of a Chlamydomonas mutant missing outer dynein arms. 214 96

The chloroplast coupling factor 1 complex (CF1) contains an epsilon-subunit which inhibits the CF1 ATPase activity. Chloroform treatment of Chlamydomonas reinhardtii thylakoid membranes solubilizes only forms of the enzyme which apparently lack the delta-subunit. Four interrelated observations are described in this paper. (1) The dithiothreitol- (DTT) induced ATPase activation of CF1(-delta) and the DTT-induced formation of a physically resolvable CF1(-delta,epsilon) from the CF1(-delta) precursor are compared. The similar time-courses of these two phenomena suggest that the dissociation of the epsilon-subunit is an obligatory process in the DTT-induced ATPase activation of soluble CF1. (2) The reversible dissociation of the epsilon-subunit of the CF1 is demonstrated by the exchange of subunits between distinguishable oligomers. 35S-labelled chloroplast coupling factor 1 lacking the delta and epsilon subunits [CF1(-delta,epsilon)] was added to a solution of non-radioactive coupling factor 1 lacking only the delta subunit [CF1(-delta)]. After separation of the two enzyme forms, via high resolution anion-exchange chromatography, radioactivity was detected in the chromatographic fractions containing CF1(-delta). (3) epsilon-deficient CF1 can be resolved from DTT pretreated epsilon-containing CF1 for several days after the removal of DTT. On the other hand, brief incubation of the DTT pretreated epsilon-containing CF1 with low concentrations of o-iodosobenzoate results in chromatographs containing only the peak of epsilon-containing CF1. A simple explanation for this phenomenon is that reduction of CF1 with DTT increases the apparent dissociation constant for the epsilon-subunit to an estimated 3.5 x 10(-8) M (+/- 1.0 x 10(-8) M) from a value of less than or equal to 5 x 10(-11) M for the oxidized enzyme. (4) ATPase activity data show that oxidation of the epsilon-deficient enzyme does not completely inhibit its manifest activity, but oxidation of DTT pre-treated CF1 which contains the epsilon-subunit completely inhibits manifest activity. A simple model is proposed for the influence of the oxidation state of the soluble enzyme on the distribution of ATPase-inactive and ATPase-active subunit configurations.
...
PMID:The dithiothreitol-stimulated dissociation of the chloroplast coupling factor 1 epsilon-subunit is reversible. 214 Jul 1

To help understand the function of inner-arm dynein in flagellar motility, dynein samples from an outer arm-missing mutant of Chlamydomonas (oda1) were examined for the ability to translocate microtubules in vitro. High-salt extract of axonemes containing inner-arm dynein was separated by ion-exchange chromatography into 7 peak fractions with ATPase activities. Of these, three fractions containing different sets of dynein heavy chains translocated microtubules. The maximal velocities were all between 3 and 5 microns/s, which were comparable to the microtubule sliding rate in disintegrating oda axonemes.
...
PMID:Microtubule translocation caused by three subspecies of inner-arm dynein from Chlamydomonas flagella. 214 76

We have sequenced the termini of the mitochondrial genome of Chlamydomonas reinhardtii and now present the DNA sequence of the gene for apocytochrome b. This gene is the thirteenth gene of the linear 15.8 kb DNA and appears to be the last one of the mt genome. The deduced protein sequence of 381 amino acid residues shows 56%, 48.6% and 48% identity with the apocytochrome b proteins of maize, Drosophila yakuba and mouse, respectively. RNA analysis reveals a transcript of about 1250 nucleotides. It is now possible to present the complete protein-coding capacity, the pattern of codon utilization for all eight protein genes, and the complete functional map of the mitochondrial 15.8 kb DNA of C. reinhardtii. One surprising feature is the absence of mitochondrial genes for ATPase and subunits II and III of cytochrome oxidase. No more than three tRNA genes appear to be present on the 15.8 kb mitochondrial DNA.
...
PMID:Mitochondrial DNA of Chlamydomonas reinhardtii: the gene for apocytochrome b and the complete functional map of the 15.8 kb DNA. 225 Jun 48


1 2 3 4 5 6 7 8 9 10 Next >>

---