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

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

The rho protein isolated from a strain of Escherichia coli with the rho1 (suA1) mutant allele is defective in interactions with RNA that are coupled to ATP hydrolysis. Here we show that the rho1 allele is partially dominant over wild-type and demonstrate that the mechanism of that dominance is due to an interference of wild-type rho factor function by the defective rho factor. The rho1 mutant protein can inhibit transcription termination and RNA-dependent ATPase activities of normal rho protein. Inhibition of the ATPase activity with excess RNA occurs by exchange of subunits to form hybrid hexamers in which the defective subunits apparently disrupt co-operative interactions essential for wild-type subunit function.
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PMID:rho factor-dependent transcription termination. Interference by a mutant rho. 294 69

A new RNA-dependent ATPase has been isolated from yeast chromatin extracts and partially characterized. The protein has a sedimentation coefficient of about 7 S. The enzyme hydrolyzes specifically ATP (or dATP) to ADP (or dADP) and Pi in the presence of Mg2+ or Mn2+ ions and requires a single-stranded polynucleotide as cofactor. The order of efficiency of synthetic polymers is poly(rU) > poly(rI) greater than or equal to poly(dU) > poly(rA) greater than or equal to poly(rC). Among natural polymers, single-stranded DNA and poly(rA)-containing mRNA from yeast are also active but less so than poly(rU). The enzyme exhibits a pH optimum of 8 and is fully inhibited by 0.25 M NaCl. The Km for ATP is0.2 mM. The resemblance between this ATPase and DNA-dependent ATPases from other sources, as well as the termination factor rho, is discussed.
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PMID:RNA-dependent ATPase from Saccharomyces cerevisiae. 610 25

An RNA-dependent ATPase has been isolated from extracts of Chlamydomonas reinhardii. The enzyme catalyzes the hydrolysis of ATP, dATP, CTP and dCTP to the corresponding nucleoside diphosphate and Pi in the presence of Mg2+ or Mn2+ and an RNA cofactor. In 1 mM MgCl2 it displays the greatest activity with poly(A), poly(I) and poly(U); and somewhat lower activity with poly(C) and T7 RNA. Although the enzyme is active with single-stranded DNA, all the single-stranded RNAs tested were significantly more effective cofactors than any of the single or double-stranded DNAs tested. A comparison of this ATPase with other RNA-dependent ATPases indicates that is has more in common with the ATPase isolated from the nuclei of animal cells than with the RNA synthesis termination protein rho, the major RNA-dependent ATPase from Escherichia coli. Although chloroplasts of C. reinhardii are known to contain many bacterial-like gene expression components, the presence of an enzyme with close homology to the E. coli rho protein was not detected.
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PMID:An RNA-dependent ATPase from Chlamydomonas reinhardII. 611 44

The effects of pyrophosphate on RNA binding and ATPase activities of Escherichia coli transcription termination factor rho have been studied. Mutant rho-115 protein has a temperature-sensitive RNA-dependent ATPase activity due to the thermolability of binding to RNA [Kent, R.B. & Guterman, S.K. (1981) Fed. Proc. Fed. Am. Soc. Exp. Biol. 40, 1765 (abstr.)]. The presence of either ATP or pyrophosphate at comparable concentrations stabilizes the binary complex of rho and poly(C) at high temperature. ADP at 8-fold greater concentration also stabilizes the mutant rho-RNA binary complex. Pyrophosphate is a noncompetitive inhibitor (Ki = 0.07 mM) of rho poly(C)-dependent ATPase, an activity that is required for rho-mediated termination. These results suggest the existence of a regulatory site on the rho molecule. We suggest that rho NTPase is regulated by RNA polymerase (EC 2.7.7.6) so that during transcription elongation the RNA polymerase competes successfully with rho for substrates and inhibits rho NTPase with product pyrophosphate. Further, RNA polymerase pausing may result in reduced pyrophosphate and increased NTP concentrations, allowing rho NTPase to function.
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PMID:Pyrophosphate inhibition of rho ATPase: a mechanism of coupling to RNA polymerase activity. 612 40

Previously, we have described an ATP-dependent recognition and binding of mRNA by eukaryotic initiation factors (eIF)-4A, eIF-4B, and eIF-4F (Grifo, J. A., Tahara, S. M., Leis, J. P., Morgan, M. A., Shatkin, A. J., and Merrick, W. C. (1982) J. Biol. Chem. 257, 5246-5252; Grifo, J. A., Tahara, S. M., Morgan, M. A., Shatkin, A. J., and Merrick, W. C. (1983) J. Biol. Chem. 258, 5804-5810). This finding was consistent with other studies which implicated eIF-4A and eIF-4B in binding mRNA to the 40 S ribosomal subunit, an ATP-requiring process. As part of ongoing studies of this step, and, in particular its ATP requirement, we have examined ATPase activity of various initiation factors. In this communication we describe an RNA-dependent ATP hydrolysis catalyzed by eIF-4A and eIF-4F. Although eIF-4B has little or no ATPase activity it can stimulate the RNA-dependent ATPase activity of either eIF-4A or eIF-4F. Similar to the ATP-dependent mRNA binding assay, the RNA-dependent ATPase activity is inhibited by the cap analogue m7GDP when globin mRNA is used as the activator. In addition, a variety of polynucleotides stimulate the ATPase activity of these factors including rRNA, tRNA, poly(U), and poly(A) but not poly(dA). Finally, an attempt has been made to discern whether phosphorylation or ATP hydrolysis is responsible for the ATP-stimulated binding of mRNA by eIF-4A and eIF-4B. We present evidence which is consistent with the interpretation that ATP hydrolysis and not protein phosphorylation correlates with ATP-stimulated binding of mRNA.
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PMID:RNA-stimulated ATPase activity of eukaryotic initiation factors. 614 16

The synthesis of RNA catalysed by RNA polymerase from Escherichia coli is terminated at specific sites on DNA templates through the action of a multimeric basic protein known as rho (refs 1, 2). Three lines of evidence suggest that an interactions of rho with the nascent RNA is important for this termination. First, rho binds strongly to RNA; second, rho expresses an RNA-dependent ATPase activity which is essential for termination; third, RNA polymerase does not terminate RNA synthesis at rho-dependent sites when the nascent RNA is digested by ribonuclease during transcription. From the fact that certain RNAs, particularly single-stranded, pyrimidine-rich polymers containing at least 10% cytidylate residues, are more effective than other RNAs at promoting rho-ATPase, it has been proposed that rho recognises specific sites oion on a mRNA transcribed from bacteriophage lambda DNA.
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PMID:A rho-recognition site on phage lambda cro-gene mRNA. 644 43

Transcription termination factor rho was purified to near homogeneity from the wild type and temperature-sensitive rho-111 mutant strains of Salmonella typhimurium. Each protein had identical physical properties with respect to native and subunit molecular weight, elution from ion-exchange columns, and poly(C)-dependent ATPase specific activity at 30 degrees C. The mutant protein exhibited a thermolabile poly(C)-dependent ATPase activity. The transcription termination and nascent RNA-dependent ATPase activities associated with the purified wild type S. typhimurium rho protein were not present in the mutant protein. Binding studies demonstrated that the stability of the rho-111:poly(C) complex was significantly more sensitive to ionic strength and temperature than that of the rho +: poly(C) complex. This result suggests that the altered activities of the mutant protein are due to its decreased ability to participate in a specific interaction with RNA which is insensitive to ionic strength. The rho-111 mutation resulted in a 20- to 30-fold elevation in the level of the mutant protein, indicating that rho biosynthesis in S. typhimurium is autogenously regulated. Therefore, defective molecular interactions between the mutant rho protein and RNA might account for the absence of transcription termination in vitro, and the polarity suppressor phenotype and defective autogenous regulation of rho biosynthesis in vivo.
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PMID:Transcription termination factor rho from wild type and rho-111 strains of Salmonella typhimurium. 646 Jul 60

Human p68 RNA helicase is a nuclear RNA-dependent ATPase that belongs to a family of putative helicases known as the DEAD box proteins. These proteins have been implicated in aspects of RNA function including translation initiation, splicing, and ribosome assembly in a variety of organisms ranging from Escherichia coli to humans. While members of this family are believed to function in the manipulation of RNA secondary structure, little is known about the regulation of these enzymes. By immunological methods and sequence comparison, we have found that p68 possesses a region of sequence similarity to the conserved protein kinase C phosphorylation site and calmodulin binding domain (also known as the IQ domain) of the neural-specific proteins neuromodulin (GAP-43) and neurogranin (RC3). We report that p68 is phosphorylated by protein kinase C in vitro and binds calmodulin in a Ca(2+)-dependent manner. Both phosphorylation and calmodulin binding inhibited p68 ATPase activity, suggesting that the RNA unwinding activity of p68 may be regulated by dual Ca2+ signal transduction pathways through its IQ domain.
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PMID:Regulation of p68 RNA helicase by calmodulin and protein kinase C. 752 83

Rho protein is required to bring about RNA release from Escherichia coli transcription complexes paused at specific (rho-dependent) termination sites. Rho functions in termination as a hexamer of identical subunits arranged in D3 symmetry, with each rho subunit carrying an RNA- and an ATP-binding site. The detailed mechanism of rho-catalyzed transcript release remains to be determined, but it is clear that the RNA-dependent ATPase activity that is stimulated by interaction with the nascent transcript is essential to the termination function of rho. In this study, we have used short (8-10 nucleotide residues) synthetic ribo-oligonucleotides to model the interaction of segments of the RNA cofactor with rho. A poly(dC) enhancement procedure was used to permit the measurement of steady state ATPase parameters. We show that (i) ATPase activation is cofactor composition- and sequence-dependent; (ii) at least 60% of the residues of these short RNA cofactors must be cytosine to produce maximal rho ATPase activation; (iii) oligo(rU,rC) cofactors with the rU residues located at the 5' termini of the oligomer are much better ATPase cofactors than oligomers containing rC residues only; (iv) this enhanced stimulation is not observed if the rU residues are replaced by rA residues; (v) this cofactor activity relative to oligo(rC) is reversed if the rU residues are placed at the 3' terminus of RNA oligomer; and (vi) these nucleotide sequence and composition effects do not appear to be functions of K+ or Mg2+ concentration. These ATPase activation results are correlated with the binding to rho of oligonucleotide cofactors in the accompanying paper (Wang, Y., and von Hippel, P. H. (1993) J. Biol. Chem. 268, 13947-13955).
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PMID:Escherichia coli transcription termination factor rho. I. ATPase activation by oligonucleotide cofactors. 831 60

PRP16 encodes an RNA-dependent ATPase required for the second step of mRNA splicing in S. cerevisiae. We have isolated seven alleles of PRP16 that, like the original allele prp16-1, allow splicing of introns with a mutant branch site (UACUAAC to UACUACC), by forming lariat intermediates at the mutant C nucleotide. Every suppressor mutation maps to the region of PRP16 common to RNA-dependent ATPases. We purified three of the mutant proteins and found that all exhibit reduced ATPase activity, as does Prp16-1. An in vivo analysis of the steady-state levels of the splicing intermediates and products provides evidence for a pathway, under the genetic control of PRP16, to discard incorrectly branched substrates. We propose that decreasing the rate of ATP hydrolysis by Prp16 allows aberrantly formed lariat intermediates more time to proceed through the productive rather than the discard branch of this pathway.
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PMID:A mechanism to enhance mRNA splicing fidelity: the RNA-dependent ATPase Prp16 governs usage of a discard pathway for aberrant lariat intermediates. 832 26


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