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Papers quoted in Current Contents on project 1-08-070

Quoted papers: 15
Other papers: 29
Total: 44

Title: Phosphorylation controls binding of acidic proteins to the ribosome

Authors:: Naranđa, Tatjana (109286); Ballesta, P.G.

Journal: Proc. Natl. Acad. Sci. USA
Number: 000
ISSN: 0027-8424
Volume: 88
Year: 1991
Pages: from 10563 to 10567
Number of references: 39
Language: engleski
Summary: The replacement of each one of the eight serine residues present in the amino acid sequence of the Saccharomyces cerevisiae acidic ribosomal phosphoprotein YP2betha(L45) by different amino acids has been performed by heteroduplex site-directed mutagenesis in the cloned gene. The mutated DNA was used to transform a yeast strain previously deprived of the original protein YP2betha(L45) by gene disruption. The replacement of serine in position 19 by either alanine, aspartic acid, or threonine prevents in vivo phosphorylation of the protein and its interaction with the ribosome. The serine-19 mutated gene is unable to rescue the negative effect on the growth rate caused by elimination of the original protein in YP2betha(L45) gene disrupted strains. The mutation of any one of the other seven serine residues has noeffect on either the phosphorylation or the ribosome binding capacity of the protein, although replacement of serine-72 seems to increase the sensitivity of the polypeptide to degradation. These results provide strong evidence indicating that ribosomal protein phosphorylation plays an important part in the activity of the particle and that it supports the existenceof a control mechanism of protein synthesis, which would regulate the level of phosphorilyation of acidic proteins.
Keywords: ribosomal protein, activity control, translation, mutagenesis

Title: The Activity-controlling Phosphorylation Site Is Not the Same in the Four Acidic Ribosomal Proteins from Saccharomyces cerevisiae

Authors:: Naranđa, Tatjana (109286); Remacha, M.; Ballesta, P.G.

Journal: J. Biol. Chem.
Number: 4
ISSN: 0021-9258
Volume: 268
Year: 1993
Pages: from 2451 to 2457
Number of references: 51
Language: englesji
Summary: By using site-directed mutagenesis and chemical analysis of phosphopeptides, a unique phosphorylation site has been shown at serine 73 in the amino acid sequence of the Saccharomyces cerevisiae acidic ribosomal protein YP1betha(L44). The mutationin this position prevents in vitro phosphorylation by protein kinases that modify the wild-type polypeptide. The unphosphorylatable mutated protein is unable to bind to the ribosomes and to rescue the growth deficiency of yeast strains inwhich the corresponding original gene is inactivated by gene disruption. Sequencing of tryptic phosphopeptides has shown that acidic proteins YPIalpha and YPIalpha(L44) are also phosphorylated at positions near the carboxiy end. These results contrast with the data indicating that in the highly homologous protein YP2betha, phosphorylation takes place at serine 19, close to the amino terminus. The results show that phosphorylation is definitely required for the biological activity of these ribosomal proteins. However, the differences in the phosphorylation sites suggest that the effect of this modification is not the same in all of them, confirming the heterologous role of these peculiar ribosomal components. Inthe four polypeptides suggests the existence of more than one protein kinase for this set of proteins.
Keywords: ribosomal protein, phosphorylation, protein kinases

Title: Stable Binding of the Eucaryotic Acidic Phosphoproteins to the Ribosome Is Not an Absolute Requirement for in Vivo Protein Syntesis

Authors:: Remacha, M.; Santos, C.; Bermejo, B.; Naranđa, Tatjana (109286); Ballesta, P.G.

Journal: J. Biol. Chem.
Number: 4
ISSN: 0021-9258
Volume: 267
Year: 1992
Pages: from 12061 to 12066
Number of references: 42
Language: engleski
Summary: The genes encoding the four acidic ribosomal phosphoproteins have been inactivated in Saccharomyces cerevisiae by recombination with truncated genes carrying different genetic markers. By crossing single haploid disruptants, strains harboring two simultanously inactivated acidic protein genes were constructed .None of the six possible double disruptions was lethal, but the simultaneous inactivation of either YP1alpha and YP1betha(L44) or YP2alpha(L44) and YP2betha(L45) caused an important decreasein the cell growth rate. Ribosomes isolated from these low-growing strains did not contain acidic proteins, not eventhe two polypeptides whose genes were still intact, although these proteins were present in the cell extracts and they seem to be able to form high-molecular weight protein complexes. Transformation of a slow-growning double transformant with a plasmid containing one of the disrupted genes restored the presence of the acidic proteins in the ribosomes and normal growth rates. The particles of the slow-growning strains were active in an in vitro amino acid polymerising system, although their activity could be stimulated by the exogenous addition of the missing proteins. These results idicate than in the absenceof either YP1alpha and YP1betha(L44) or YP2alpha(L44) andYP2betha(L45), the remaining acidie proteins are unable to interact with the ribosome in a stable manner, but that a strong interaction of these ribosomal components with the particle is not an absolute requirement for in vivo and in vitro protein synthesis.
Keywords: in vivo protein syntesis, ribosomal protein, translation

Title: Yeast seryl-tRNA synthetase expressed in Escherichia coli recognized bacterial serine-specific tRNA in vivo

Authors:: Weygand-Đurašević, Ivana (57696); Ban, Nenad; Jahn, D.; Soll, Dieter

Journal: Eur. J. Biochem.
Number: 214
ISSN: 0014-2956
Volume: 214
Year: 1993
Pages: from 869 to 877
Number of references: 42
Language: engleski
Summary: The Saccharomyces cerevisiae serS gene which encodes seryl-tRNA synthetase (SerRS) was expressed in Escherichia coli from the promoter and the ribosome binding sequences contained in its own 5-flanking region. The low level of yeast SerRS in the procaryotic host was sufficient to permit in vivo complementationof two temperature-sensitive E.coli serS mutants at the nonpermissive temperature. Thus, yeast SerRS can aminoacylate E.coli tRNA(Ser) species in vivo. Yeast SerRS, isolated from an overexpressing E.coli strain by a rapid two-step purification on FPLC, aminoacylated E.coli tRNA with serine much more poorly (relative kcat/Km = 0,0002) than its homologous tRNAs. DL-serine hydroxamate, an inhibitor of E. coli SerRS, inhibits yeast SerRS in vivo and in vitro with an inhibition constant (Ki) of 2,7 mM, a value 90-fold higher than for E. coli SerRS.
Keywords: seryl-tRNA synthetase, tRNA recognition, protein overproduction, FPLC, complementation

Title: Acceptor end binding domain interactions ensure correct aminoacylation of transfer RNA

Authors:: Weygand-Đurašević, Ivana (57696); Schwob, Etienne; Soll, Dieter

Journal: Proc. Natl. Acad. Sci. USA
ISSN: 0027-8424
Volume: 90
Year: 1993
Pages: from 2010 to 2014
Number of references: 32
Language: engleski
Summary: The recognition of the acceptor stem of tRNA(Gln) is an important element ensuring the accuracy of aminoacylation by Escherichia coli glutaminyl-tRNA synthetase (GlnRs; EC6.1.1.18). On the basis of known mutations and the crystal structure of the tRNA(Gln). GlnRS complex, we mutagenized at saturation two motifs in the acceptor end binding domain of GlnRS. Mutants with lowered tRNA specificity were then selected in vivo by suppression of a glutamine-specific amber mutation (lacZ1000) with an amber suppressor tRNA derived from tRNA(Ser1). The mischarging GlnRs mutants obtained in this way retain the ability to charge tRNA(Gln), but in addition, they misacylate a number of noncognate amber suppressor tRNAs. The critical residues responsible for specificity are Arg-130 and Glu-131, located in a part of GlnRS that binds the acceptor stem of tRNA(Gln). On the basis of the spectrum of tRNAs capable of bening misacylated by such mutants we propose than, in addition to taking part in productive interactions, the acceptor end binding domain contributes to recognition specifycity by rejecting noncognate tRNAs through negative interaction. Analysis of thecatalytic properties of one of the mischarging enzymes, GlnRS100(Arg-130 -- Pro, Glu-131 -- Asp), indicates than, while the kinetic parameters of the mutant enzyme are not dramatically changed, it binds noncognate tRNA(Glu) more stably than the wild-type enzyme does (Kd is 1/8 that of the wild type). Thus the stability of the noncognate complex may be the basis for mischarging in vivo.
Keywords: tRNA specificity, aminoacyl-tRNA synthetase, nonsense suppression

Title: Coexpression of Eukaryotic tRNA(Ser) and Yeast Seryl-tRNA Synthetase Leads to Funtcional Amber Suppression in Escherichia coli

Authors:: Weygand-Đurašević, Ivana (57696); Nalaskowska, M.; Soll, Dieter

Journal: J. Bacteriol.
Number: 1
ISSN: 0021-9190
Volume: 376
Year: 1994
Pages: from 232 to 239
Number of references: 47
Language: engleski
Summary: In order to gain insight into the conservation of determinants for tRNA identity between organisms, Schizosaccharomyces pombe and human amber suppressor serine tRNA genes have been examined for functional expression in Escherichia coli. The primary transcripts, which originated from E.coli plasmid promoters, were processed into mature tRNAs, but they were poorly aminoacylated in E.coli and thus were nonfuctional as supprssor,in vivo. However, coexpression of cloned Saccharomyces cerevisiae seryl-tRNA synthetase led to efficient suppression in E.coli. This shows that some, but not all, determinants specifying the tRNA(Ser) identity are conserved in evolution.
Keywords: heterologous expression, yeast seryl-tRNA synthetase, tRNA recognition, suppression

Title: The recognition of E. coli glutamine tRNA by glutaminyl-tRNA synthetase

Authors:: Rogers, M.J.; Weygand-Đurašević, Ivana (57696); Schwob, Etienne; Sherman, J.M.; Rogers, K.C.; Thomann, H.U.; Sylvers, L.A.; Ohtsuka, Eiko; Inokuchi, H.; Soll, Dieter

Journal: Nucleic Acidic Symposium Series
ISSN: 0261-3166
Volume: 29
Year: 1993
Pages: from 211 to 213
Number of references: 13
Language: engleski
Summary: A variety of genetic, biochemical and structural studies have been used to determine factors ensuring the accuracy of recognition by aminoacyl-tRNA synthetases for tRNA.The identity elements of Escherichia coli tRNA(Gln) are located mainly in the anticodon and acceptor stem, and ensure the accurate recognition of the tRNA by glutaminyl-tRNA synthetase. We summarize a number of experimental techniques to define the accuracy of aminoacylation in vivo and in vitro.
Keywords: tRNA, aminoacyl-tRNA synthetases

Title: Thiobacillus ferrooxidans tyrosyl-tRNA synthetase functions in vivo in Escherichia coli

Authors:: Salazar, Oriana; Sagredo, Boris; Jedlicki, Eugenia; Soll, Dieter; Weygand-Đurašević, Ivana (57696); Orellana, Omar

Journal: J. Bacteriol.
Number: 14
ISSN: 0021-8424
Volume: 176
Year: 1994
Pages: from 4409 to 4415
Number of references: 27
Language: engleski
Summary: The tyrosyl-tRNA synthetase gene (tyrZ) from Thiobacillus ferrooxidans, an acidophilic, autotrophic, gram-negative bacterium that participates in bioleaching of minerals, was cloned and sequenced. The encoded polypeptide (TyrRZ) is 470 amino acids in length (molecular mass; 38 kDa). The predicted protein sequence has an extensive overall identity (44%) to the sequence of the protein encoded by the Bacillus subtilis tyrZ gene, one of the two genes encoding tyrosyl-tRNA synthetases in this microorganism. Alignment with Escherichia coli TyrRS revealed limited overall identity (24%), except in the regions of the signature sequence for class I aminoacyl-tRNA synthetases. Complementation of an E. coli strain with a thermosensitive mutation in TyrRS showed that the protein encoded by the T. ferrooxidans tyrZ gene is functional and recognizes the E. coli tRNA(Tyr) as a substrate. TyrZ is a single-copy gene as revealed by Southern blot analysis. The gene is located upstream from the putative promoters of the rrnT2 ribosomal RNA operon. Although no rho-independent transcription terminator was found between the two genes, a 1.3-kb RNA hybridized to a DNA probe derived from the tyrZ gene. The functional relationship between these two transcription units is discussed.
Keywords: tRNA, amonoacyl-tRNA synthetase

Title: Selectivity and specificity in the recognition of tRNA by E. coli glutaminyl-tRNA synthetase

Authors:: Rogers, M.J.; Weygand-Đurašević, Ivana (57696); Schwob, Etienne; Sherman, J.M.; Rogers, K.C.; Adachi, T; Inokuchi, H.; Soll, Dieter

Journal: Biochimie
ISSN: 0300-9084
Volume: 75
Year: 1993
Pages: from 1083 to 1090
Number of references: 42
Language: engleski
Summary: The specific recognition by Escherichia coli glutaminyl-tRNA synthetase (GlnRS) of tRNA(Gln) is mediated by extensive protein:tRNA contacts and changes in the conformation of tRNA(Gln) when complexed with GlnRS. In vivo accuracy of aminoacylation depends on two factors: competition between synthetases, and the context and recognition of identity elements in the tRNA. The structure of the tRNA(Gln):GlnRS complex supports studies from amber and opal suppressor tRNAs, complemented by in vitro aminoacylation of mutated tRNA transcripts, that the glutamine identity elements are located in the anticodon and acceptor stem of tRNA(Gln). Recognition of individual functional groups in tRNA, for example the 2-amino group of guanosine, is also evident from the result with inosine- substituted tRNAs. Communication between anticodon and acceptor stem recognition is indicated by mutants in GlnRS isolated by genetic selection with opal suppressor tRNAs which are altered in interactions with the inside of the L-shaped tRNA. We have also used genetic selection to obtain mutants of GlnRS altered in acceptor stem recognition with relaxed specificity for amber suppressor tRNAs, and a more extensive mutational analysis shows the importance of the acceptor binding domain to accurate recognition of tRNA.
Keywords: tRNA, aminoacyl-tRNA synthetase mutants

Title: Connecting anticodon recognition with the active site of Escherichia coli glutaminil-tRNA synthetase

Authors:: Weygand-Đurašević, Ivana (57696); Rogers, M.J.; Soll, Dieter

Journal: J. Mol. Biol.
ISSN: 0022-2836
Volume: 240
Year: 1994
Pages: from 111 to 118
Number of references: 24
Language: engleski
Summary: Escherichia coli glutaminyl-tRNA synthetase (GlnRS) specifically recognizes nucleotides in the anticodon and acceptor stem of tRNA(Gln). Extensive conformational changes in the tRNA(Gln):GlnRS complex and requirement for tRNA glutaminyl-adenylate formation suggests that accurate anticodon recognition is required for aminoacylation. A 17 amino acid loop in GlnRS (residues 476 to 492) that connects two beta-ribbon motifs was targeted for saturation mutagenesis as the motifs span the anticodon binding domain and extend to the active site. Opal suppressor tRNAs (GLN) derived from tRNA(Gln) are poor substrates for GlnRS, and compensating mutations in glnS (the structural gene for GlnRS) were selected by the ability of mutant gene product to aminoacylate such a suppressor (GLNA3U70). A number of mutations in loop 476 to 492 were identified by genetic selection, and two of the GlnRS purified mutant enzymes showed elevated specificity constants (kcat/Km) for aminoacylation of tRNA(Gln)-derived transcript with the opal (UCA) anticodon when compared with the wild-type enzyme. The specificity constants for the mutant enzymes with the cognate tRNA(Gln) transcript (anticodon CUG) were unchanged. Therefore, region 476 to 492 has been identified in communicating anticodon recognition with the active site at a distance of more than 30 A away, supporting a proposed model from the structure of the complex between tRNA(Gln):GlnRS. A previous study has been identified residues that interact with the inside of the L-shaped tRNA as communicating accurate anticodon recognition. Therefore, at least two pathways of communication have been identified in the accurate recognition of tRNA by GlnRS.
Keywords: tRNA, aminoacyl-tRNA synthetase, opal suppressor

Title: Substrate selection by aminoacyl-tRNA synthetases

Authors:: Ibba, Michael; Thomann, H.U.; Hong, Kwang-Won; Sherman, J.M.; Weygand-Đurašević, Ivana (57696); Sever, Sanja (179365); Stange-Thomann, Nicole; Praetorius, Mette; Soll, Dieter

Journal: Nucleic Acidic Symposium Series
ISSN: 0261-3166
Volume: 0000
Year: 1995
Pages: from 0000 to 0000
Number of references: 12
Language: engleski
Summary: The integration of genetic and biochemical approaches to study the crystal structure of the glutaminyl-tRNA synthetase (GlnRS):tRNA(Gln):ATP complex has elucidated the mechanism by which GlnRS selects its cognate tRNA for aminoacylation. Three principal types of interaction have been identified: interaction with specific bases in the cognate tRNA, rejection of non-cognate tRNAs, and activation of the active site upon cognate tRNA binding. The recent solving of the crystal structure of tryptophanyl-tRNA synthetase (TrpRS) has allowed comparable studies to be initiated in an aminoacyl-tRNA synthetase which, unlike GlnRS, does not require tRNA binding prior to amino acid activation.
Keywords: tRNA selection

Title: The system for studyimg the specificity of serylation with yeast seryl-tRNA synthetase

Authors:: Weygand-Đurašević, Ivana (57696)

Journal: Croatica Chem. Acta
ISSN: 0011-1643
Volume: 0000
Year: 1995
Pages: from 0000 to 0000
Number of references: 55
Language: engleski
Summary: Serylation is the covalent attachment of serine to a specific tRNA. It is catalyzed by the seryl-tRNA synthetase (SerRS). Presumably there are two seryl-tRNA synthetases, encoded by different nuclear genes, that perform the serylation task in Saccharomyces cerevisiae. One works in cytoplasm and the other one in mitochondria. The gene for cytoplasmic enzyme has been cloned, sequenced and can be functionally expressed both in yeast and in Escherichia coli. Its protein product is 106 kD homodimer, which can be easily purified from bacterial and yeast overproducing strains. The enzyme recognizes six tRNA(Ser) isoacceptors and selenocysteine tRNA in yeast, as well as several nonhomologous tRNAs from prokaryotic and eukaryotic sources. By the combination of genetic and biochemical methods, the system for studying the recognition between yeast seryl-tRNA synthetase and its substrates, both in vivo and in vitro has been established.
Keywords: seryl-tRNA synthetase, tRNA(Ser)

Title: The C-terminal extension of yeast seryl-tRNA synthetase affects stability of the enzyme and its substrate affinity

Authors:: Weygand-Đurašević, Ivana (57696); Lenhard, Boris; Filipić, Sanda; Soll, Dieter

Journal: J. Biol. Chem.
ISSN: 0021-9258
Volume: 0000
Year: 1995
Number of references: 44
Language: engleski
Summary: Saccharomyces cerevisiae seryl-tRNA synthetase (SerRS) contains a 20 amino acid carboxy-terminal extension which is not found in prokaryotic SerRS enzymes. A truncated yeast SES1 gene, lacking the 60 base pairs which encode this C-terminal domain, is able to complement a yeast SES1 null allele strain; thus the C-terminal extension in SerRS is dispensable for the viability of the cell. However, the removal of the C-terminal peptide affects both stability of the enzyme and its affinity for the substrates. The truncation mutant binds tRNA with 3.6-fold higher affinity, while Km for serine is four-fold increased relative to the wild-type SerRS. This indicates the importance of the C-terminal extension in maintaining the overall structure of SerRS.
Keywords: seryl-tRNA synthetase, C-terminal extension

Title: SV40-Transformed human cells in crisis exhibit changes that occur in normal cellular senescence

Authors:: Rubelj, Ivica (108443); Pereira-Smith, O.M.

Journal: Exp. Cell Res.
ISSN: 0014-4827
Volume: 211
Year: 1994
Pages: from 82 to 89
Number of references: 32
Language: engleski
Summary: SV40 antigen can induce senescent human diploid fibroblasts to synthesize DNA; however cells fail to go through mitosis. In this study, we examined the expression of the cdc2 and cyclin B genes, which are required for completion of mitosis, to determine whether defects in their expression occured when SV40-transformed human cells entered the phase of crisis. If deffects were observed it would indicate that immortalization by the virus involved reexpression of these genes. We found that the expression of cdc2 was unmpaired at both the RNA and protein levels, but the cyclin B expression was decreased in cells in crisis when compared with precrisis (mortal) and postcrisis (immortal) cells. Tritilated thymidine uptake demonstrated that the majority of the cells in crisis were not actively cycling. consistent with the latter observation we found that cyclin A, which is required for cells to traverse through S to G2, was down regulated in these cells. Since many of the results obtained with cells in crisis were similar to what is observed in normal human cells when they become senescent, we analyzed the expression of the genes fibronectin and sdi1 (a gene recently cloned from senescent cells that codes for an inhibitor of DNA synthesis). Both genes were overexpressed in cells during crisis, as in the case with senescent cells. The results were discussed in terms of the two-stage model previously proposed to explain the process of immortalization of human diploid fibroblasts by SV40.
Keywords: cell crisis, cell cycle

Title: A boimarker for cellular replicative senescence in culture and in vivo

Authors:: Dimri, G.P.; Lee, X.; Basile, G.; Acosta, M.; Scot, G.; Roskelley, C.; Medrano, E.; Linskens, M.; Rubelj, Ivica (108443); Pereira-Smith, O.M.; Peacocke, M.; Campisi, J.

Journal: Proc. Natl. Acad. Sci. USA
ISSN: 0027-8424
Volume: 0000
Year: 1995
Pages: from 00000 to 00000
Language: engleski
Keywords: cell crisis; cell cycle


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