Glu-tRNA
            <sup>Gln</sup>
            amidotransferase: A novel heterotrimeric enzyme required for correct decoding of glutamine codons during translation

Curnow, Alan W.; Hong, Kwang Won; Yuan, Robert; Kim, Sŭng-il; Martins, Orlando B.; Winkler, William E.; Henkin, Tina M.; Söll, Dieter

doi:10.1073/pnas.94.22.11819

Cited by 299 publications

(328 citation statements)

References 29 publications

(32 reference statements)

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“…In other bacteria, archaea, and some organelles however, AspRS is a non-canonical, non-discriminating enzyme (ND-AspRS) that generates both AsptRNA Asp and the misacylated Asp-tRNA Asn (5)(6)(7)12,3,14). This Asp-tRNA Asn is converted to Asn-tRNA Asn by a glutamine-dependent Asp-tRNA Asn /Glu-tRNA Gln amidotransferase (Asp/ Glu-Adt) (26,27,9,28,12). ND-AspRS is most commonly found in organisms lacking asparaginyl-tRNA synthetase (AsnRS) and in these cases, the combination of ND-AspRS and Asp/Glu-Adt provides the sole route for Asn-tRNA Asn biosynthesis and, in some cases, for asparagine biosynthesis as well (7,29).…”

Section: Introductionmentioning

confidence: 99%

The Nondiscriminating Aspartyl-tRNA Synthetase from Helicobacter pylori: Anticodon-Binding Domain Mutations That Impact tRNA Specificity and Heterologous Toxicity

Chuawong

Hendrickson

2006

Biochemistry

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Divergent tRNA substrate recognition patterns distinguish the two distinct forms of aspartyl-tRNA synthetase (AspRS) that exist in different bacteria. In some cases, a canonical, discriminating AspRS (D-AspRS) specifically generates Asp-tRNA Asp and usually co-exists with asparaginyl-tRNA synthetase (AsnRS). In other bacteria, particularly those that lack AsnRS, AspRS is nondiscriminating (ND-AspRS) and generates both Asp-tRNA Asp and the non-canonical, misacylated Asp-tRNA Asn ; this misacylated tRNA is subsequently repaired by the glutamine-dependent AsptRNA Asn /Glu-tRNA Gln amidotransferase (Asp/Glu-Adt). The molecular features that distinguish the closely related bacterial D-AspRS and ND-AspRS are not well understood. Here we report the first characterization of the ND-AspRS from the human pathogen Helicobacter pylori. This enzyme is toxic when heterologously overexpressed in E. coli. This toxicity is rescued upon co-expression of the H. pylori Asp/Glu-Adt, indicating that Hp Asp/Glu-Adt can utilize E. coli Asp-tRNA Asn as a substrate. Finally, mutations in the anticodon-binding domain of Hp ND-AspRS reduce this enzyme's ability to misacylate tRNA Asn , in a manner that correlates with the toxicity of the enzyme in E. coli.

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Section: Introductionmentioning

confidence: 99%

The Nondiscriminating Aspartyl-tRNA Synthetase from Helicobacter pylori: Anticodon-Binding Domain Mutations That Impact tRNA Specificity and Heterologous Toxicity

Chuawong

Hendrickson

2006

Biochemistry

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“…These coupled glutaminases, termed glutamine amidotransferase (GAT) domains, have been classified as members of the triad-type or the N-terminal nucleophile-type superfamilies (14). More recently, a superfamily of aminoacyltRNA trans-amidases were described as a third unrelated type of GAT (15). Here we show that a domain related to nitrilase (16) containing a conserved Glu-Lys-Cys catalytic triad (16) is the long sought GAT domain for eukaryotic NAD ϩ synthetase, Qns1 (Q for glutamine-dependent, NAD ϩ synthetase).…”

mentioning

confidence: 99%

Eukaryotic NAD+ Synthetase Qns1 Contains an Essential, Obligate Intramolecular Thiol Glutamine Amidotransferase Domain Related to Nitrilase

Bieganowski¹,

Pace²,

Brenner³

2003

Journal of Biological Chemistry

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NAD ؉ is an essential co-enzyme for redox reactions and is consumed in lysine deacetylation and poly(ADPribosyl)ation. NAD ؉ synthetase catalyzes the final step in NAD ؉ synthesis in the well characterized de novo, salvage, and import pathways. It has been long known that eukaryotic NAD ؉ synthetases use glutamine to amidate nicotinic acid adenine dinucleotide while many purified prokaryotic NAD ؉ synthetases are ammoniadependent. Earlier, we discovered that glutamine-dependent NAD ؉ synthetases contain N-terminal domains that are members of the nitrilase superfamily and hypothesized that these domains function as glutamine amidotransferases for the associated synthetases. Here we show yeast glutamine-dependent NAD ؉ synthetase Qns1 requires both the nitrilase-related active-site residues and the NAD ؉ synthetase active-site residues for function in vivo. Despite failure to complement the lethal phenotype of qns1 disruption, the former mutants retain ammonia-dependent NAD ؉ synthetase activity in vitro, whereas the latter mutants retain basal glutaminase activity. Moreover, the two classes of mutants fail to trans-complement despite forming a stable heteromultimer in vivo. These data indicate that the nitrilaserelated domain in Qns1 is the fourth independently evolved glutamine amidotransferase domain to have been identified in nature and that glutamine-dependence is an obligate phenomenon involving intramolecular transfer of ammonia over a predicted distance of 46 Å from one active site to another within Qns1 monomers.Nicotinamide-adenine dinucleotide (NAD ϩ ) 1 and its phosphorylated form NADP are essential for oxidizing reactions in the cell, whereas reduced forms of these co-enzymes, NADH and NADPH, are essential for supplying reducing equivalents. Beyond the reversible functions of NAD ϩ in hundreds of enzymedependent redox reactions, at least two types of enzymes consume NAD ϩ in eukaryotic nuclei in the process of forming or reversing post-translational modifications. Poly(ADP-ribose) polymerases respond to DNA strand breaks by transferring the ADP-ribose moiety of NAD ϩ to target proteins, thereby facilitating DNA repair and other processes (1, 2). Sirtuins, a family of protein lysine-deacetylases related to yeast Sir2, reverse regulatory acetyl modification of lysines on histones, p53, and other proteins typically to alter the assembly of nucleoprotein complexes (3, 4). NAD ϩ is consumed by Sir2 to produce a mixture of 2Ј-and 3Ј-O-acetylated ADP-ribose plus nicotinamide and the deacetylated polypeptide (5). NAD ϩ -dependent deacetylation reactions are required not only for alterations in gene expression but also for repression of ribosomal DNA recombination and extension of lifespan in response to calorie restriction (6, 7). In prokaryotes, Sirtuins perform lysine deacetylation to alter chromatin structure (8) as well as to regulate acetyl-CoA synthetase and potentially other metabolic enzymes (9).Interest in the biological functions of Sir2 and Sirtuins has lead to re-examination of the biosynthetic ro...

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“…Both genomes encode 36 transfer RNA species, each mapping to the same relative location. Neither strain contains Asn or Gln tRNA species; however, we have identi®ed homologues for the Bacillus subtilis gatABC genes (gene JHP769/HP0830, JHP603/HP0658 and JHP909/HP0975; H. pylori J99 genes are numbers attached to the pre®x`JHP'), which amidate glutamate charged tRNAs to make glutamine-charged tRNAs 6 . Such genes are also likely to be responsible for amidation of appropriate aspartatecharged tRNAs.…”

Section: Methodsmentioning

confidence: 99%

“…Close to its C terminus, titin contains a MLCK-like kinase domain. Although sequence similarity of the catalytic domain of titin to that of its invertebrate analogue, the serine/threonine kinase domain of twitchin 6 , has indicated that titin and twitchin may have similar function, the differential localization of the kinase domains 7,8 , their distinct C-terminal regulatory tails 9,10 and the presence of several titin-specific residues in the active site 11 hint at a different function for titin. Twitchin is a Ca 2+ /S100A1-regulated MLCK 12 .…”

mentioning

confidence: 99%

Erratum: Genomic-sequence comparison of two unrelated isolates of the human gastric pathogen Helicobacter pylori

Alm¹,

Ling²,

Moir³

et al. 1999

Nature

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Ubx-homeodomain electron density, and polyalanine helices were placed into the Exd-homeodomain density. The MIRAS map was further improved by cycles of solvent¯attening with program DM 24 . Using these and F o 2 F c and 2F o 2 F c maps, interspersed with positional and individual B-factor re®nement using X-PLOR 26 , the model was rebuilt, side chains were added, and the Exd loops and N-terminal arms were built with the program O (ref. 27). The ®rst four residues of Exd, the residues from -7 to 4 of Ubx and the ®rst 6 residues of Ubx were disordered. There was clear density for the YPWM motif, but it was not readily interpretable for residues other than the tryptophan side chain. To obtain a more interpretable map, we re®ned and improved the MIRAS phases by solvent¯attening and extended them to 2.8 A Ê using the program SHARP 28 . This map was greatly improved and showed us how to ®t the YPWM motif. The YPWM ®t was further veri®ed by an anomalous-difference Fourier map calculated with data measured from selenomethionine (SeMet)-substituted protein; this map showed the positions of the three substituted seleniums, including the one in the YPWM motif. The re®nement of the structure was extended to 2.4 A Ê resolution using the native 1 data, and the structure veri®ed through extensive simulated annealing omit maps. Finally, 110 water molecules were added from the inspection of F o 2 F c maps. The ®nal re®ned structure has good stereochemistry, with the Ramachandran plot showing 84.5% of the residues in the core allowed regions and no residues in the disallowed or generously allowed regions.Received 18 December 1998; accepted 3 February 1999. The giant muscle protein titin (connectin) is essential in the temporal and spatial control of the assembly of the highly ordered sarcomeres (contractile units) of striated muscle. Here we present the crystal structure of titin's only catalytic domain, an autoregulated serine kinase (titin kinase). The structure shows how the active site is inhibited by a tyrosine of the kinase domain. We describe a dual mechanism of activation of titin kinase that consists of phosphorylation of this tyrosine and binding of calcium/calmodulin to the regulatory tail. The serine kinase domain of titin is the first known non-arginine-aspartate kinase to be activated by phosphorylation. The phosphorylated tyrosine is not located in the activation segment, as in other kinases, but in the P þ 1 loop, indicating that this tyrosine is a binding partner of the titin kinase substrate. Titin kinase phosphorylates the muscle protein telethonin in early differentiating myocytes, indicating that this kinase may act in myofibrillogenesis.Protein kinases are important in controlling cell proliferation and differentiation and they require specific mechanisms of regulation and substrate recognition [1][2][3] . Tight control of the enzymatic activity of protein kinases is achieved by phosphorylation of specific residues in the activation segment of the catalytic domain, sometimes combined with reversible conforma...

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Glu-tRNA ^Gln amidotransferase: A novel heterotrimeric enzyme required for correct decoding of glutamine codons during translation

Cited by 299 publications

References 29 publications

The Nondiscriminating Aspartyl-tRNA Synthetase from Helicobacter pylori: Anticodon-Binding Domain Mutations That Impact tRNA Specificity and Heterologous Toxicity

The Nondiscriminating Aspartyl-tRNA Synthetase from Helicobacter pylori: Anticodon-Binding Domain Mutations That Impact tRNA Specificity and Heterologous Toxicity

Eukaryotic NAD+ Synthetase Qns1 Contains an Essential, Obligate Intramolecular Thiol Glutamine Amidotransferase Domain Related to Nitrilase

Erratum: Genomic-sequence comparison of two unrelated isolates of the human gastric pathogen Helicobacter pylori

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Glu-tRNA Gln amidotransferase: A novel heterotrimeric enzyme required for correct decoding of glutamine codons during translation

Cited by 299 publications

References 29 publications

The Nondiscriminating Aspartyl-tRNA Synthetase from Helicobacter pylori: Anticodon-Binding Domain Mutations That Impact tRNA Specificity and Heterologous Toxicity

The Nondiscriminating Aspartyl-tRNA Synthetase from Helicobacter pylori: Anticodon-Binding Domain Mutations That Impact tRNA Specificity and Heterologous Toxicity

Eukaryotic NAD+ Synthetase Qns1 Contains an Essential, Obligate Intramolecular Thiol Glutamine Amidotransferase Domain Related to Nitrilase

Erratum: Genomic-sequence comparison of two unrelated isolates of the human gastric pathogen Helicobacter pylori

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Glu-tRNA ^Gln amidotransferase: A novel heterotrimeric enzyme required for correct decoding of glutamine codons during translation