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| Subject | Predicate | Object |
|---|---|---|
| http://purl.uniprot.org/citations/12731872 | http://www.w3.org/1999/02/22-rdf-syntax-ns#type | http://purl.uniprot.org/core/Journal_Citation |
| http://purl.uniprot.org/citations/12731872 | http://www.w3.org/1999/02/22-rdf-syntax-ns#type | http://purl.uniprot.org/core/Journal_Citation |
| http://purl.uniprot.org/citations/12731872 | http://www.w3.org/1999/02/22-rdf-syntax-ns#type | http://purl.uniprot.org/core/Citation |
| http://purl.uniprot.org/citations/12731872 | http://www.w3.org/2000/01/rdf-schema#comment | "The bacterial enzyme S-adenosylmethionine:tRNA ribosyltransferase-isomerase (QueA) catalyzes the unprecedented transfer and isomerization of the ribosyl moiety of S-adenosylmethionine (AdoMet) to a modified tRNA nucleoside in the biosynthesis of the hypermodified nucleoside queuosine. The complexity of this reaction makes it a compelling problem in fundamental mechanistic enzymology, and as part of our mechanistic studies of the QueA-catalyzed reaction, we report here the elucidation of the steady-state kinetic mechanism. Bi-substrate kinetic analysis gave initial velocity patterns indicating a sequential mechanism, and provided the following kinetic constants: K (M)(tRNA)= 1.9 +/-0.7 microM and K (M)(AdoMet)= 98 +/-5.0 microM. Dead-end inhibition studies with the substrate analogues S-adenosylhomocysteine and sinefungin gave competitive inhibition patterns against AdoMet and noncompetitive patterns against preQ(1)-tRNA(Tyr), with K(i) values of 133 +/- 18 and 4.6 +/-0.5 microM for sinefungin and S-adenosylhomocysteine, respectively. Product inhibition by adenine was noncompetitive against both substrates under conditions with a subsaturating cosubstrate concentration and uncompetitive against preQ(1)-tRNA(Tyr) when AdoMet was saturating. Inhibition by the tRNA product (oQ-tRNA(Tyr)) was competitive and noncompetitive against the substrates preQ(1)-tRNA(Tyr) and AdoMet, respectively. Inhibition by methionine was uncompetitive versus preQ(1)-tRNA(Tyr), but noncompetitive against AdoMet. However, when methionine inhibition was investigated at high AdoMet concentrations, the pattern was uncompetitive. Taken together, the data are consistent with a fully ordered sequential bi-ter kinetic mechanism in which preQ(1)-tRNA(Tyr) binds first followed by AdoMet, with product release in the order adenine, methionine, and oQ-tRNA. The chemical mechanism that we previously proposed for the QueA-catalyzed reaction [Daoud Kinzie, S., Thern, B., and Iwata-Reuyl, D. (2000) Org. Lett. 2, 1307-1310] is consistent with the constraints imposed by the kinetic mechanism determined here, and we suggest that the magnitude of the inhibition constants for the dead-end inhibitors may provide insight into the catalytic strategy employed by the enzyme."xsd:string |
| http://purl.uniprot.org/citations/12731872 | http://purl.org/dc/terms/identifier | "doi:10.1021/bi034197u"xsd:string |
| http://purl.uniprot.org/citations/12731872 | http://purl.org/dc/terms/identifier | "doi:10.1021/bi034197u"xsd:string |
| http://purl.uniprot.org/citations/12731872 | http://purl.uniprot.org/core/author | "Iwata-Reuyl D."xsd:string |
| http://purl.uniprot.org/citations/12731872 | http://purl.uniprot.org/core/author | "Iwata-Reuyl D."xsd:string |
| http://purl.uniprot.org/citations/12731872 | http://purl.uniprot.org/core/author | "Van Lanen S.G."xsd:string |
| http://purl.uniprot.org/citations/12731872 | http://purl.uniprot.org/core/author | "Van Lanen S.G."xsd:string |
| http://purl.uniprot.org/citations/12731872 | http://purl.uniprot.org/core/date | "2003"xsd:gYear |
| http://purl.uniprot.org/citations/12731872 | http://purl.uniprot.org/core/date | "2003"xsd:gYear |
| http://purl.uniprot.org/citations/12731872 | http://purl.uniprot.org/core/name | "Biochemistry"xsd:string |
| http://purl.uniprot.org/citations/12731872 | http://purl.uniprot.org/core/name | "Biochemistry"xsd:string |
| http://purl.uniprot.org/citations/12731872 | http://purl.uniprot.org/core/pages | "5312-5320"xsd:string |
| http://purl.uniprot.org/citations/12731872 | http://purl.uniprot.org/core/pages | "5312-5320"xsd:string |
| http://purl.uniprot.org/citations/12731872 | http://purl.uniprot.org/core/title | "Kinetic mechanism of the tRNA-modifying enzyme S-adenosylmethionine:tRNA ribosyltransferase-isomerase (QueA)."xsd:string |
| http://purl.uniprot.org/citations/12731872 | http://purl.uniprot.org/core/title | "Kinetic mechanism of the tRNA-modifying enzyme S-adenosylmethionine:tRNA ribosyltransferase-isomerase (QueA)."xsd:string |
| http://purl.uniprot.org/citations/12731872 | http://purl.uniprot.org/core/volume | "42"xsd:string |
| http://purl.uniprot.org/citations/12731872 | http://purl.uniprot.org/core/volume | "42"xsd:string |
| http://purl.uniprot.org/citations/12731872 | http://www.w3.org/2004/02/skos/core#exactMatch | http://purl.uniprot.org/pubmed/12731872 |
| http://purl.uniprot.org/citations/12731872 | http://www.w3.org/2004/02/skos/core#exactMatch | http://purl.uniprot.org/pubmed/12731872 |
| http://purl.uniprot.org/citations/12731872 | http://www.w3.org/2004/02/skos/core#exactMatch | http://purl.uniprot.org/pubmed/12731872 |
| http://purl.uniprot.org/citations/12731872 | http://xmlns.com/foaf/0.1/primaryTopicOf | https://pubmed.ncbi.nlm.nih.gov/12731872 |
| http://purl.uniprot.org/citations/12731872 | http://xmlns.com/foaf/0.1/primaryTopicOf | https://pubmed.ncbi.nlm.nih.gov/12731872 |