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Flavin-Dependent Methylation of RNAs: Complex Chemistry for a Simple Modification. J Mol Biol 2016; 428:4867-4881. [PMID: 27825927 DOI: 10.1016/j.jmb.2016.10.031] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 10/19/2016] [Accepted: 10/31/2016] [Indexed: 12/28/2022]
Abstract
RNA methylation is the most abundant and evolutionarily conserved chemical modification of bases or ribose in noncoding and coding RNAs. This rather simple modification has nevertheless major consequences on the function of maturated RNA molecules and ultimately on their cellular fates. The methyl group employed in the methylation is almost universally derived from S-adenosyl-L-methionine via a simple SN2 displacement reaction. However, in some rare cases, the carbon originates from N5,N10-methylenetetrahydrofolate (CH2=THF). Here, a methylene group is transferred first and requires a subsequent reduction step (2e-+H+) via the flavin adenine dinucleotide hydroquinone (FADH-) to form the final methylated derivative. This FAD/folate-dependent mode of chemical reaction, called reductive methylation, is thus far more complex than the usual simple S-adenosyl-L-methionine-dependent one. This reaction is catalyzed by flavoenzymes, now named TrmFO and RlmFO, which respectively modify transfer and ribosomal RNAs. In this review, we briefly recount how these new RNA methyltransferases were discovered and describe a novel aspect of the chemistry of flavins, wherein this versatile biological cofactor is not just a simple redox catalyst but is also a new methyl transfer agent acting via a critical CH2=(N5)FAD iminium intermediate. The enigmatic structural reorganization of these enzymes that needs to take place during catalysis in order to build their active center is also discussed. Finally, recent findings demonstrated that this flavin-dependent mechanism is also employed by enzymatic systems involved in DNA synthesis, suggesting that the use of this cofactor as a methylating agent of biomolecules could be far more usual than initially anticipated.
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Kerr SJ, Borek E. The tRNA methyltransferases. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2006; 36:1-27. [PMID: 4563428 DOI: 10.1002/9780470122815.ch1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Lane BG, Ofengand J, Gray MW. Pseudouridine and O2'-methylated nucleosides. Significance of their selective occurrence in rRNA domains that function in ribosome-catalyzed synthesis of the peptide bonds in proteins. Biochimie 1995; 77:7-15. [PMID: 7599278 DOI: 10.1016/0300-9084(96)88098-9] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Pseudouridine (5-ribosyluracil, psi) was the first of a host of modified nucleoside constituents detected in cellular RNA and it remains the most abundant, being broadly distributed in the RNA of archaebacteria, eubacteria and eukaryotes. Like some other modifications, psi is particularly abundant in more complex organisms, reaching 2-3% of the total nucleoside constituents in tRNA, snRNA and rRNA of multicellular plants and animals. Like all other modified nucleosides, psi arises by site-specific, enzymically catalyzed modification of a nucleoside residue in an RNA molecule. Unlike all other modified nucleosides, psi arises by isomerisation (not substitution) of a classical nucleoside, uridine (1-ribosyluracil). There have been suggestions that key processes such as ribosome assembly and peptidyl transfer may rely, more than is generally appreciated, on RNA modifications such as O2'-methylation and pseudouridylation, respectively. However, a persuasive case for the view that secondary modifications are of primary importance in ribosome function has not been convincingly made. Accordingly, we think it is timely to broaden what is generally meant by the 'catalytic properties of rRNA', and to ask, to what extent do modifications contribute to in vivo rates of ribosome assembly and ribosomal peptide-bond synthesis? The first part of this article sets forth the evidence that there is a conspicuous association between modified nucleosides and cellular RNAs that participate in group-transfer reactions. The second part reviews evidence in support of the view that the functions of psi and other modified nucleosides are likely of central importance for understanding the dynamics and stereostructural modeling at functionally significant sites in the ribosome.
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Affiliation(s)
- B G Lane
- Biochemistry Department, University of Toronto, ON, Canada
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Chapter 1 Synthesis and Function of Modified Nucleosides in tRNA. ACTA ACUST UNITED AC 1990. [DOI: 10.1016/s0301-4770(08)61487-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Ajitkumar P, Cherayil JD. Thionucleosides in transfer ribonucleic acid: diversity, structure, biosynthesis, and function. Microbiol Rev 1988; 52:103-13. [PMID: 3280963 PMCID: PMC372707 DOI: 10.1128/mr.52.1.103-113.1988] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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7
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Weissenbach J, Grosjean H. Effect of threonylcarbamoyl modification (t6A) in yeast tRNA Arg III on codon-anticodon and anticodon-anticodon interactions. A thermodynamic and kinetic evaluation. EUROPEAN JOURNAL OF BIOCHEMISTRY 1981; 116:207-13. [PMID: 6788546 DOI: 10.1111/j.1432-1033.1981.tb05320.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The effect of N-[9-(beta-D-ribofuranosyl) purin-6-ylcarbamoyl]threonine (t6A) adjacent to anticodon U-C-U of yeast tRNA Arg III (where U is a modified U), compared to its unmodified adenosine counterpart, has been evaluated by three independent methods: (a) the polynucleotide-directed binding of tRNA on ribosomes, (b) the ribosome-free trinucleotide binding to the anticodon, (c) the anticodon-anticodon binding test. The results obtained by these three methods indicate a small but significant stabilization effect of t6A on the binding of yeast tRNA Arg III with (a) poly(A,G) in the presence of Escherichia coli ribosomes, (b) free A-G-A triplet, and (c) E. coli tRNA Ser V (anticodon G-G-A). We therefore conclude that the stabilization effect of t6A occurs on U x A and U x G base pairs adjacent to the 5' side of the modified nucleoside, most probably by stacking.
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Abstract
The methylation patterns of transfer and ribosomal ribonucleic acid (RNA) from two mycoplasmas, Mycoplasma capricolum and Acholeplasma laidlawii, have been examined. The transfer RNA from the two mycoplasmas resembled that of other procaryotes in degree of methylation and general diversity of methylated nucleotides, and bore particular resemblance to Bacillus subtilis transfer RNA. The only unusual feature was the absence of m5U from M. capricolum transfer RNA. The methylation patterns of the mycoplasma 16S RNAs were also typically procaryotic, retaining the methylated residues previously shown to be highly conserved among eubacterial 16S RNAs. The mycoplasma 23S RNA methylation patterns were, on the other hand, quite unusual. M. capricolum 23S RNA contained only four methylated residues in stoichiometric amounts, all of which were ribose methylated. A. laidlawii 23S RNA contained the same ribose-methylated residues, plus in addition approximately six m5U residues. These findings are discussed in relation to the phylogenetic status of mycoplasma, as well as the possible role of RNA methylation.
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Gupta R, Woese CR. Unusual modification patterns in the transfer ribonucleic acids of archaebacteria. Curr Microbiol 1980. [DOI: 10.1007/bf02605865] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Janner F, Vögeli G, Fluri R. The antisuppressor strain sin1 of Schizosaccharomyces pombe lacks the modification isopentenyladenosine in transfer RNA. J Mol Biol 1980; 139:207-19. [PMID: 7411631 DOI: 10.1016/0022-2836(80)90305-8] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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11
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Vani BR, Ramakrishnan T, Taya Y, Noguchi S, Yamaizumi Z, Nishimura S. Occurrence of 1-methyladenosine and absence of ribothymidine in transfer ribonucleic acid of Mycobacterium smegmatis. J Bacteriol 1979; 137:1084-7. [PMID: 374335 PMCID: PMC218285 DOI: 10.1128/jb.137.3.1084-1087.1979] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The minor base composition of Mycobacterium smegmatis tRNA has been studied. Thin-layer chromatographic patterns of a ribonuclease T2 digest of mycobacterial tRNA indicated the presence of appreciable amounts of 1-methyladenosine (which is commonly present only in eucaryotic tRNA), dihydrouridine, and 7-methylguanosine. Ribothymidine was absent. The S-adenosylmethionine-dependent tRNA methylases of M. smegmatis catalyzed the formation of 1-methyladenosine when Escherichia coli tRNA was used as acceptor. Similarly, E. coli extracts methylated the tRNA of M. smegmatis, forming ribothymidine.
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Feldman M. Minor components in transfer RNA: The location-function relationships. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 1978. [DOI: 10.1016/0079-6107(78)90018-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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14
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Coppola S, Zoina A, Marino P. Cyclic-AMP content in Escherichia coli B/b as affected by N1-(delta 2-isopentyl)adenine. ZENTRALBLATT FUR BAKTERIOLOGIE, PARASITENKUNDE, INFEKTIONSKRANKHEITEN UND HYGIENE. ZWEITE NATURWISSENSCHAFTLICHE ABTEILUNG: MIKROBIOLOGIE DER LANDWIRTSCHAFT DER TECHNOLOGIE UND DES UMWELTSCHUTZES 1978; 133:245-9. [PMID: 211751 DOI: 10.1016/s0323-6056(78)80010-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
N6-(delta 2-isopentenyl)adenine, like other cytokinins, does not detectably modify Escherichia coli growth, but strongly affects cellular levels of cAMP. A substantial delay of the highest level of intracellular cAMP, a reduction to about one half of such maximum level, and a slight increase of cAMP secreted into the medium are reported.
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Pegg AE. Formation and metabolism of alkylated nucleosides: possible role in carcinogenesis by nitroso compounds and alkylating agents. Adv Cancer Res 1977; 25:195-269. [PMID: 326002 DOI: 10.1016/s0065-230x(08)60635-1] [Citation(s) in RCA: 247] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Abstract
The methylation of tRNA is a post-transcriptional modification which is achieved by specific enzymes, the tRNA methylases, with S adenosylmethionine as a methyl donor. The level and pattern of methylation are characteristic of the tRNA species and origin. Abnormally methylated tRNAs have been obtained, in vivo and in vitro, by a variety of methods, and their properties have been studied. The tRNA methylases are found in all cells and tissues. Their activity varies with the differentiation state of the cells, and under the influence of many internal and external factors ; it is especially elevated in embryonic and cancerous tissues. These enzymes are very unstable, and none of them has been purified to homogeneity. We present here their known properties and we propose a theory concerning their specificity. Finally, after reviewing the few available experimental data, we discuss the current hypotheses and speculations about the roles and functions of tRNA methylation.
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Walker RT, RajBhandary UL. Formylatable methionine transfer RNA from Mycoplasma: purification and comparison of partial nucleotide sequences with those of other prokaryotic initiator tRNAs. Nucleic Acids Res 1975; 2:61-78. [PMID: 1093144 PMCID: PMC342811 DOI: 10.1093/nar/2.1.61] [Citation(s) in RCA: 44] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The major species of the formylatable methionine tRNA from Mycoplasma mycoides var capri has been purified. The 5'- and 3'-terminal sequences of the purified tRNA are pC-G- and C-A-A-C-C-AOH, respectively. Thus, this tRNA also contains the unique structural feature found in two other prokaryotic initiator tRNAs in that the first nucleotide at the 5'-end cannot form a Watson-Crick type of base-pair to the fifth nucleotide from the 3'-end. The Mycoplasma tRNA does not contain ribothymidine; however, a specific uridine residue in the sequence G-U-psi-C-G- can be enzymatically methylated by E. coli extracts to yield G-T-psi-C-G. Since ribothymidine is absent in crude tRNA from this strain of Mycoplasma, the absence of T is probably due to the lack of a U yields T modifying enzyme.
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Ecarot B, Cedergren RJ. Methionine transfer RNAs from the blue-green alga Anacystis nidulans. BIOCHIMICA ET BIOPHYSICA ACTA 1974; 340:130-9. [PMID: 4208972 DOI: 10.1016/0005-2787(74)90105-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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20
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Liska B, Smith PF. Requirements of Acholeplasma laidlawii A, strain LA 1, for nucleic acid precursors. Folia Microbiol (Praha) 1974; 19:107-17. [PMID: 4471597 DOI: 10.1007/bf02872843] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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21
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Initiation of Protein Synthesis by Folate-sufficient and Folate-deficient Streptococcus faecalis R. J Biol Chem 1974. [DOI: 10.1016/s0021-9258(19)42960-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Sharma OK. Differences in the transfer RNA methyltransferases from normal rat liver and Novikoff hepatoma. BIOCHIMICA ET BIOPHYSICA ACTA 1973; 299:415-27. [PMID: 4349332 DOI: 10.1016/0005-2787(73)90266-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Gallo RC, Hecht SM, Whang-Peng J, O'Hopp S. N 6 -( 2 -Isopentenyl)adenosine: the regulatory effects of a cytokinin and modified nucleoside from tRNA on human lymphocytes. BIOCHIMICA ET BIOPHYSICA ACTA 1972; 281:488-500. [PMID: 4653127 DOI: 10.1016/0005-2787(72)90149-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Samuel CE, Rabinowitz JC. Effect of formylation on the chromatographic behavior of methionyl transfer ribonucleic acid. Anal Biochem 1972; 47:244-52. [PMID: 4624155 DOI: 10.1016/0003-2697(72)90298-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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32
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Bartz JK, Söll D. N 6 -( 2 -isopentenyl) adenosine: biosynthesis in vitro in transfer RNA by an enzyme purified from Escherichia coli. Biochimie 1972; 54:31-9. [PMID: 4346747 DOI: 10.1016/s0300-9084(72)80035-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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33
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34
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Johnson L, Söll D. Temperature dependence of the aminoacylation of tRNA by Bacillus stearothermophilus aminoacyl-tRNA synthetases. Biopolymers 1971; 10:2209-21. [PMID: 4940767 DOI: 10.1002/bip.360101114] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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35
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Johnson JD, Horowitz J. Characterization of ribosomes and RNAs from Mycoplasma hominis. BIOCHIMICA ET BIOPHYSICA ACTA 1971; 247:262-79. [PMID: 4942459 DOI: 10.1016/0005-2787(71)90675-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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36
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Walker RT. Biosynthetic precursors of some modified nucleosides in the transfer ribonucleic acid of Mycoplasma mycoides var. capri. J Bacteriol 1971; 107:618-22. [PMID: 5095284 PMCID: PMC246979 DOI: 10.1128/jb.107.3.618-622.1971] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The ribosomal and transfer ribonucleic acid (tRNA) from Mycoplasma mycoides var. capri, grown in a medium containing uridine-((14)C)-5'-triphosphate and cytidine-(5-(3)H)-5'-triphosphate, were isolated and separated. The uridine in both species of RNA was shown to contain (14)C and the cytidine to contain both (3)H and (14)C. Comparison of the labeling of 4-thiouridine and pseudouridine, obtained from an enzymatic digest of the RNA, indicates that their biosynthetic precursor is uridine, not cytidine. It is probable that ribothymidine and dihydrouridine have the same derivation.
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MESH Headings
- Carbon Isotopes
- Chemical Precipitation
- Cytidine/analysis
- Cytosine Nucleotides/metabolism
- Dialysis
- Freeze Drying
- Genetics, Microbial
- Hydrolysis
- Mycoplasma/analysis
- Mycoplasma/metabolism
- Nucleosides/analysis
- RNA, Bacterial/analysis
- RNA, Bacterial/biosynthesis
- RNA, Bacterial/isolation & purification
- RNA, Ribosomal/analysis
- RNA, Ribosomal/biosynthesis
- RNA, Ribosomal/isolation & purification
- RNA, Transfer/analysis
- RNA, Transfer/biosynthesis
- RNA, Transfer/isolation & purification
- Tritium
- Uracil Nucleotides/metabolism
- Uridine/analysis
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Abstract
The molecular events leading to the synthesis of mature tRNA are only now becoming amenable to experimental study. In bacterial and mammalian cells tRNA genes are transcribed into precursor tRNA. These molecules, when isolated, contain additional nucleotides at both ends (20) of the mature tRNA and lack most modified nucleosides. Presumably, specific nucleases ("trimming" enzymes) cut the precursor to proper tRNA size. The C-C-A nucleotide sequence of the amino acid acceptor end common to all tRNA's does not seem to be coded by tRNA genes (30), and may be added to the trimmed molecules by the tRNA-CMP-AMP-pyrophosphorylase (71). Modifications at the polynucleotide level of the heterocyclic bases or the sugar residues give rise to the modified nucleosides in tRNA. Although newly available substrates have allowed the detection of more of the enzymes involved in these reactions, there is still no knowledge about the sequence of modification or trimming events leading to the synthesis of active tRNA. Progress in these studies may not be easy because enzyme preparations free of nucleases or other tRNA modifying enzymes are required. The role of the modified nucleosides in the biological functions of tRNA is still unknown. Possibly pseudouridine is required for ribosome mediated protein synthesis; some other modified nucleosides in tRNA are not required for this reaction, but may enhance its rate. What might be the role of the large variety of modified nucleosides in tRNA? One is tempted to speculate that such nucleosides are important in other cellular processes in which tRNA is thought to participate such as virus infection, cell differentiation, and hormone action (2, 3). Mutants in a number of tRNA-modifying enzymes are needed in order to extend our knowledge of their purpose and of tRNA involvement in other biological processes. But unless tRNA-modifying enzymes specific for a particular tRNA species exist, no simple selection procedure can be devised. Possibly some of the regulatory mutants of amino acid biosynthesis may prove to affect tRNA-modifying enzymes (72). Transfer RNA's are macromolecules well suited for the study of nucleic acid-protein interactions. The tRNA molecules are structurally very similar, and they interact with a large number of enzymes or protein factors (2, 3). Each aminoacyl-tRNA synthetase, for instance, very precisely recognizes a set of cognate isoacceptor tRNA's (2, 73). The availability of the tRNA- modifying enzymes adds another dimension to the problem of the nature of specific recognition of tRNA by proteins. There are some tRNA-modifying enzymes, such as the uracil-tRNA methylase, which may recognize all tRNA species, while others, such as the isopentenyl-tRNA transferase, probably recognize only a selected set of tRNA molecules, even with different amino acid accepting capacities. With well-characterized RNA precursor and tRNA molecules we can hope to delineate those features of primary, secondary, and tertiary structure involved in the specific interactions of tRNA with these enzymes.
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Matsushita T, Davis FF. Studies on pseudouridylic acid synthetase from various sources. BIOCHIMICA ET BIOPHYSICA ACTA 1971; 238:165-73. [PMID: 4936431 DOI: 10.1016/0005-2787(71)90082-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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39
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Litwack MD, Peterkofsky A. Transfer ribonucleic acid deficient in N6-(delta 2-isopentenyl)adenosine due to mevalonic acid limitation. Biochemistry 1971; 10:994-1001. [PMID: 4994513 DOI: 10.1021/bi00782a010] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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40
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Feldmann H, Falter H. Transfer ribonucleic acid from Mycoplasma laidlawii A. EUROPEAN JOURNAL OF BIOCHEMISTRY 1971; 18:573-81. [PMID: 5545013 DOI: 10.1111/j.1432-1033.1971.tb01278.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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42
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Burkard G, Guillemaut P, Weil JH. Comparative studies of the tRNA's and the aminoacyl-tRNA synthetases from the cytoplasm and the chloroplasts of Phaseolus vulgaris. BIOCHIMICA ET BIOPHYSICA ACTA 1970; 224:184-98. [PMID: 4321417 DOI: 10.1016/0005-2787(70)90632-5] [Citation(s) in RCA: 88] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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43
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In vitro biosynthesis of pseudouridine at the polynucleotide level by an enzyme extract from Escherichia coli. Proc Natl Acad Sci U S A 1970; 67:943-50. [PMID: 4943184 PMCID: PMC283296 DOI: 10.1073/pnas.67.2.943] [Citation(s) in RCA: 42] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
DNA from Mycoplasma sp. Kid which was enriched for tRNA genes (containing about 10% tDNA) was transcribed by E. coli RNA polymerase. The RNA transcription product labeled with [(14)C]uridine was formed in good yield (70-fold net synthesis). After incubation of this [(14)C]uridine-labeled RNA with E. coli extracts, nucleotide analyses revealed that [(14)C]pseudouridine was formed. The experiments support the idea that the conversion of uridine to pseudouridine takes place at the macromolecular level. Furthermore, the conversion was shown to be specific for a uridine residue in tRNA-like material since neither [(14)C]polyuridylic acid nor the [(14)C]uridine-labeled RNA transcribed from lambda DNA served as substrate for the pseudouridine-forming enzyme(s).
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44
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Bartz JK, Kline LK, Söll D. N6-(Delta 2-isopentenyl)adenosine: biosynthesis in vitro in transfer RNA by an enzyme purified from Escherichia coli. Biochem Biophys Res Commun 1970; 40:1481-7. [PMID: 4326583 DOI: 10.1016/0006-291x(70)90035-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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45
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Smith PF, Smith MR. Cholesterol inhibition of isopentenyl pyrophosphate delta3, delta2-isomerase in Mycoplasma laidlawii. J Bacteriol 1970; 103:27-31. [PMID: 4316364 PMCID: PMC248034 DOI: 10.1128/jb.103.1.27-31.1970] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Cholesterol inhibits isopentenyl Delta(3),Delta(2)-isomerase of Mycoplasma laidlawii in an apparently competitive fashion. The conversion of mevalonic acid to isopentenyl pyrophosphate is slightly stimulated. Organisms grown in the presence of mevalonic-2-(14)C acid contain small amounts of radio-label in nucleic acid and protein fractions. Most of the label is found in the lipids and is reduced dramatically in organisms grown with cholesterol. No significant accumulation of phosphorylated intermediates of polyterpene biosynthesis was observed in cells or culture supernatant fluid. All of the radioactivity appearing in the nucleic acid fraction occurs in the minor nucleoside, isopentenyl adenosine, of the transfer ribonucleic acid. The necessity for synthesis by the organisms of this minor nucleoside from mevalonic acid may explain the site of enzyme inhibition by cholesterol of polyterpene biosynthesis.
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Chirikdjian JG, Davis FF. Compositional Variations in the Common Pentanucleotide from Transfer Ribonucleic Acids of Escherichia coli. J Biol Chem 1970. [DOI: 10.1016/s0021-9258(18)63235-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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