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1.
Summary The nucleotide sequence of a 1105 by Streptomyces rimosus DNA fragment containing five transfer RNA genes was determined. Two tRNAGln (CUG) genes, differing by 1 by in the aminoacyl stem, and three identical tRNAGlu (CUC) genes were identified. The five tRNA genes, arranged in the order: Gln1-Glul-Glu2-Gln2-Glu3, were separated by short, nonhomologous intergenic regions. Surprisingly, none of these tRNA genes encoded the CCA 3 terminus of mature tRNAs. All five encoded tRNAs for the translation of GC rich codons, which are preferentially used in Streptomyces genes (CAG and GAG, respectively). We recently reported nucleotide sequences of two initiator tRNA genes from S. rimosus, which also do not encode the CCA end of mature tRNAs. It is therefore very likely that S. rimosus represents an example of those eubacteria in which the majority of tRNA genes do not encode the 3 terminal CCA end of mature tRNAs. Evolutionary implications of this finding remain to be elucidated. 相似文献
2.
Summary The chloroplast genome contains genes for a large and probably complete set of tRNAs. These genes are unique in sharing attributes of both nuclear and bacterial tRNA genes. Two chloroplast tRNA genes from Zea mays are described here. tV-UAC, encoding a valine tRNA with the anticodon UAC, contains a 603 bp intron and is highly homologous, both in coding regions and in the intron, to the analogous gene from tobacco described by Deno et al. (Nucleic Acids Res 10:7511–7520, 1982). It is located near the gene for the beta and epsilon subunits of the CF1 complex. (Krebbers et al.: Nucleic Acids Res 10:4985–5002, 1982). The gene tS-UGA, encoding a serine tRNA with the anticodon UGA, is located 41 kbp 3 to tV-UAC. Both genes contain promoter-like sequences in their 5 flanking regions. 相似文献
3.
The prokaryotic tet operator (tetO) sequence was inserted at positions upstream and downstream of sequences encoding the Arabidopsis thaliana tRNA
AUC
Lys
or tRNA
AUC
Trp
suppressor tRNAs, and tRNA expression in carrot protoplasts was measured by translational suppression of a nonsense codon in a luciferase reporter gene. Regulation of tRNA expression by the tetracycline repressor (tetR) occurred from genes with the tetO inserted at position –1 (for the tRNA
AUC
Trp
gene), or at positions –2, –6 and –10 (for the tRNA
AUC
Lys
gene), and repression reached 90%. The inducer tetracycline (Tc) restored tRNA expression. Similarly, carrot protoplasts transfected with human tRNA
AUC
Ser
genes containing the lac operator (lacO) in their 5-flanking sequence with or without the lac repressor (lacI) gene, conditionally expressed tRNAs which suppressed the luciferase reporter. Up to 30-fold repression occured by the lactose repressor when lacO was located at position –1 of the tRNA
AUC
Ser
coding sequence. In the presence of the inducer isopropyl--thiogalactoside (IPTG), repression was relieved. These results demonstrate that sequences flanking tRNA genes can strongly influence tRNA expression in plants, and in a conditional fashion when bound by inducible proteins. 相似文献
4.
Takashi Horiuchi Tetsuji Nagasawa Kyoko Takano Mutsuo Sekiguchi 《Molecular & general genetics : MGG》1987,206(2):356-357
Summary We report a new tRNA
1
Asp
gene near the dnaQ gene, which is located at 5 min on the Escherichia coli linkage map. We named it aspV. The sequence corresponding to the mature tRNA is identical with that of the two previously identified tRNA
1
Asp
genes (aspT and aspU), but there is no homology in the sequences of their 3-and 5-flanking regions.Abbreviations kb
kilo base pair(s)
- rrn
ribosomal RNA 相似文献
5.
Géraldine Bonnard François Michel Jacques Henry Weil André Steinmetz 《Molecular & general genetics : MGG》1984,194(1-2):330-336
Summary The gene encoding the tRNA
UAA
Leu
from broad bean chloroplasts has been located on a 5.1 kbp long BamHI fragment by analysis of the DNA sequence of an XbaI subfragment. This gene is 536 bp long and is split in the anticodon region. The 451 bp long intron shows high sequence homology over about 100 bp from each end with the corresponding regions of the maize chloroplast tRNA
UAA
Leu
intron. These conserved sequences are probably involved in the splicing reaction, for they can be folded into a secondary structure which is very similar to the postulated structure of the intron from the autosplicable ribosomal RNA precursor of Tetrahymena. Very little sequence conservation is found in the 5-and 3-flanking regions of the broad bean and maize chloroplast tRNA
UAA
Leu
genes. 相似文献
6.
Michael J. Smith David K. Banfield Karin Doteval Sharon Gorski David J. Kowbel 《Journal of molecular evolution》1990,31(3):195-204
Summary We have cloned and sequenced over 9 kb of the mitochondrial genome from the sea starPisaster ochraceus. Within a continuous 8.0-kb fragment are located the genes for NADH dehydrogenase subunits 1, 2, 3, and 4L (ND1, ND2, ND3, and ND4L), cytochrome oxidase subunits I, II, and III (COI, COII, and COIII), and adenosine triphosphatase subunits 6 and 8 (ATPase 6 and ATPase 8). This large fragment also contains a cluster of 13 tRNA genes between ND1 and COI as well as the genes for isoleucine tRNA between ND1 and ND2, arginine tRNA between COI and ND4L, lysine tRNA between COII and ATPase 8, and the serine (UCN) tRNA between COIII and ND3. The genes for the other five tRNAs lie outside this fragment. The gene for phenylalanine tRNA is located between cytochrome b and the 12S ribosomal genes. The genes for tRNAglu and tRNAthr are 3 to the 12S ribosomal gene. The tRNAs for histidine and serine (AGN) are adjacent to each other and lie between ND4 and ND5. These data confirm the novel gene order in mitochondrial DNA (mtDNA) of sea stars and delineate additional distinctions between the sea star and other mtDNA molecules. 相似文献
7.
We have previously reported that four tRNAs of Drosophila melanogaster randomly labeled with iodine-125 hybridize in part to the 56EF region of polytene chromosomes where 5S RNA genes occur. In the presence of a 100-fold excess of unlabeled 5S RNA no hybridization of randomly labeled 125I-tRNAAsp
2 occurred at 56EF although hybridization elsewhere was not affected. In addition, tRNAAsp
2 labeled by introducing 125I-5-iodocytidylyl residues into the 3-CCA end with tRNA nucleotidyl transferase did not hybridize to 56EF but did hybridize to its other sites. The hybridization of tRNALys
2, tRNAGly
3 and tRNAMet
3 at 56EF was not eliminated by a 25 to 100-fold excess of unlabeled 5S RNA. When these tRNAs were labeled at the -CCA terminus they hybridized to 56EF as well as to their other sites with the exception that terminally labeled tRNALys
2 no longer hybridized to 62A. The hybridization of the latter three species of tRNA to the region of the 5S genes, amongst other sites, is confirmed. The previously observed hybridization of tRNAAsp
2 in this region appears to have been due to contamination of the tRNA sample with traces of material derived from 5S RNA. 相似文献
8.
Six purified tRNAs labeled with 125I by chemical or enzymatic methods were hybridized to polytene chromosomes of Drosophila melanogaster. The main chromosomal regions of hybridization were: tRNA
GGA
Gly
, 58A, 84C, and 90E; tRNA
2
Leu
, 44E, 66B5-8, and 79F; tRNA
2b
Ser
, 86A, 88A9-12, and 94A6-8; tRNA
3
Thr
, 47F and 87B; tRNA
4
Thr
, 93A1-2; and tRNA
1
Tyr
, 19F, 22F-23A, 41, 50C1-4 and 85A. At 50C the hybridization of tRNA
1
Tyr
was polymorphic in the giant strains. When the hybridization of three valine isoacceptors studied previously was re-investigated, it was found that only one hybridization site, 90BC, was shared between tRNA
3b
Val
and tRNA
4
Val
. tRNA
3a
Val
did not have any sites in common with the other two. 相似文献
9.
Masataka Kinjo Masahiro Ishigami Tsunemi Hasegawa Kei Nagano 《Journal of molecular evolution》1984,20(1):59-65
Summary Interaction based on possible chemical affinity of an amino acid for tRNA was examined as a model for the aminoacylation of primitive tRNA without aid of an enzyme system. Two types of reaction were carried out and compared. One was the acyl linkage of amino acid to the 5-terminal phosphate of a tRNA activated as an imidazolide. The other was the incorporation of an amino acid activated as an imidazolide into 2(3)-hydroxyl groups of intact tRNA. Both types of reaction indicated that none of the amino acids tested had any selectivity for the tRNAs examined. However, the rates of reaction with a given tRNA were different among amino acids. In the second type of reaction, amino acids were found mainly at loop-out regions of tRNA, but not at either its 5- or 3-terminal sitesOneA
260 unit is defined as an amount of material which gives an absorption of 1.0 at 260 nm when dissolved in 1 ml water and measured with a 1-cm light path 相似文献
10.
D Richter 《Molecular & general genetics : MGG》1980,178(2):325-327
Summary The spoT gene product from Escherichia coli, the guanosine 3,5-bis(diphosphate) 3-pyrophosphohydrolase [ppGppase] catalyzes the specific release of pyrophosphate from the 3-position of guanosine 3,5-bis(diphosphate) [ppGpp]; this reaction is significantly inhibited in the presence of uncharged tRNA
yeast
Phe
. Little or no inhibition is observed with Phe-tRNAPhe, tRNAPhe-CpCpAoxi-red or ribosomal RNA (16S and 23S). 相似文献
11.
Bergmann Pascale Seyer Patrick Burkard Gérard Weil Jacques-Henri 《Plant molecular biology》1984,3(1):29-36
Tobacco chloroplast tRNAs have been purified by two-dimensional polyacrylamide gel electrophoresis, identified by aminoacylation, labelled at their 3-end and hybridized to tobacco chloroplast DNA restriction fragments, in order to establish a tRNA gene map. These hybridization studies have revealed the localization of at least seven genes in each inverted repeat region, a minimum of 22 tRNA genes in the large single copy region and one tRNA gene in the small single copy region. Comparison of the tobacco chloroplast tRNA gene map to that of maize shows many similarities, but also some differences suggesting that DNA sequence rearrangements have occurred in the chloroplast genome during evolution. 相似文献
12.
tRNA species that read codons starting with adenosine (A) contain N6-threonylcarbamoyladenosine (t6A) derivatives adjacent to and 3′ of the anticodons from all organisms. In Escherichia coli there are 12 such tRNA species of which two (tRNAGGUThr1 and tRNAGGUThr3) have the t6A derivative N6-methyl-N6-threonylcarbamoyladenosine (m6t6A37). We have isolated a mutant of E. coli that lacks the m6t6A37 in these two tRNAGGUThr species. These tRNA species in the mutant are likely to have t6A37 instead of m6t6A37. We show that the methyl group of m6t6A37 originates from S-adenosyl-l-methionine and that the gene (tsaA) which most likely encodes tRNA(m6t6A37)methyltransferase is located at min 4.6 on the E. coli chromosomal map. The growth rate of the cell, the polypeptide chain elongation rate, and the selection of Thr-tRNAGGUThr to the ribosomal A site programmed with either of the cognate codons ACC and ACU were the same for the tsaA1 mutant as for the congenic wild-type strain. The expression of the threonine operon is regulated by an attenuator which contains in its leader mRNA seven ACC codons that are read by these two m6t6A37-containing tRNAGGUThr species. We show that the tsaA1 mutation resulted in a twofold derepression of this operon, suggesting that the lack of the methyl group of m6t6A37 in tRNAGGUThr slightly reduces the efficiency of this tRNA to read cognate codon ACC.All tRNA species from the three domains, Archaea, Bacteria, and Eucarya, contain modified nucleosides, which are derivatives of the four nucleosides, adenosine, guanosine, cytidine, and uridine. At present, more than 79 different modified nucleosides from the tRNA of various organisms have been characterized (23). Some of these are present in tRNA from only one domain, but a few are present in the same subset of and at the same position in the tRNAs from all three domains (3). One such conserved group of modified nucleosides is the threonylated adenosine (t6A) derivatives. These modified adenosines are present adjacent to and 3′ of the anticodon (position 37) in the subset of tRNAs that reads codons starting with A. The universal presence of t6A derivatives suggests that these kinds of modifications may have been present in the tRNA of the progenitor, unless a convergent evolution has occurred. This conservation also suggests that the functions of these modified nucleosides may be principally the same in all organisms.In Escherichia coli, the t6A37 derivative N6-methyl-N6- threonylcarbamoyladenosine (m6t6A37) is present in only two tRNA species, the tRNAGGUThr species, with the same anticodon (20). Threonine is the precursor in the synthesis of t6A (10, 32), and in vitro threonylation requires carbonate and ATP (15, 21). Here we show that the methyl group of m6t6A37 originates from methionine. So far, no mutant deficient in any t6A37 derivative has been characterized. As a first step to elucidate the syntheses of these groups of modified nucleosides and their roles in vivo, we have isolated and characterized a mutant deficient in the synthesis of m6t6A37. We show that the tsaA gene most likely encodes the tRNA(m6t6A37)methyltransferase that transfers a methyl group from S-adenosylmethionine (AdoMet) to the two tRNAGGUThr species containing the t6A moiety. The tsaA gene was localized to the 4.6 min site on the E. coli chromosome. We also show that the methyl group of m6t6A37 slightly improves the translational efficiency of the two tRNAGGUThr species. 相似文献
13.
Intron-containing tRNA genes are exceptional within nuclear plant genomes. It appears that merely two tRNA gene families coding for tRNATyr
G A and elongator tRNAMet
CmAU contain intervening sequences. We have previously investigated the features required by wheat germ splicing endonuclease for efficient and accurate intron excision from Arabidopsis pre-tRNATyr. Here we have studied the expression of an Arabidopsis elongator tRNAMet gene in two plant extracts of different origin. This gene was first transcribed either in HeLa or in tobacco cell nuclear extract and splicing of intron-containing tRNAMet precursors was then examined in wheat germ S23 extract and in the tobacco system. The results show that conversion of pre-tRNAMet to mature tRNA proceeds very efficiently in both plant extracts. In order to elucidate the potential role of specific nucleotides at the 3 and 5 splice sites and of a structured intron for pre-tRNAMet splicing in either extract, we have performed a systematic survey by mutational analyses. The results show that cytidine residues at intron-exon boundaries impair pre-tRNAMet splicing and that a highly structured intron is indispensable for pre-tRNAMet splicing. tRNA precursors with an extended anticodon stem of three to four base pairs are readily accepted as substrates by wheat and tobacco splicing endonuclease, whereas pre-tRNA molecules that can form an extended anticodon stem of only two putative base pairs are not spliced at all. An amber suppressor, generated from the intron-containing elongator tRNAMet gene, is efficiently processed and spliced in both plant extracts. 相似文献
14.
Richard F. Selden Andre Steinmetz Lee McIntosh Lawrence Bogorad Gerard Burkard Mfika Mubumbila Marcel Kuntz Edwin J. Crouse Jacques H. Weil 《Plant molecular biology》1983,2(3):141-153
A minimum of 37 genes corresponding to tRNAs for 17 different amino acids have been localized on the restriction endonuclease cleavage site map of theZea mays chloroplast DNA molecule. Of these, 14 genes corresponding to tRNAs for 11 amino acids are located in the larger of the two single-copy regions which separate the two inverted copies of the repeat region. One tRNA gene is in the smaller single-copy region. Each copy of the large repeated sequence contains, in addition to the ribosomal RNA genes, 11 tRNA genes corresponding to tRNAs for 8 amino acids. The genes for tRNA2 Ile and tRNAAla map in the ribosomal spacer sequence separating the 16S and 23S ribosomal RNA genes. The three isoaccepting species for the tRNAsLeu and the three for tRNAsSer, as well as the two isoaccepting species for tRNAAsn, tRNAGly, tRNAsIle, tRNAsMet, tRNAsThr, are shown to be encoded at different loci. Two independent methods have been used for the localization of tRNA genes on the physical map of the maize chloroplast DNA molecule: (a) cloned chloroplast DNA fragments were hybridized with radioactively-labelled total 4S RNAs, the hybridized RNAs were then eluted, and identified by two-dimensional polyacrylamide gel electrophoresis, and (b) individual tRNAs were32P-labelledin vitro and hybridized to DNA fragments generated by digestion of maize chloroplast DNA with various restriction endonucleases. 相似文献
15.
Kirk Hayenga Charles Hedgcoth Mary Harrison Victor K. Lin B. J. Ortwerth 《Molecular and cellular biochemistry》1986,71(1):25-30
Summary Mouse lymphoma cells have three major isoaccepting lysine tRNAs. Two of these isoacceptors, tRNA2
Lys and tRNA4
Lys, were sequenced by rapid gel or chromatogram readout methods. They have the same primary sequence but differ in two modified nucleotides. tRNA4
Lys has an unmodified uridine replacing one dihydrouridine and an unidentified nucleotide, t6A*, replacing t6A. This unidentified nucleotide is not a hypomodified form of t6A. Thus, tRNA4ys is not a simple precursor of tRNA2
Lys. Both tRNAs have an unidentified nucleotide, U**, in the third position of the anticodon. Also, partial sequences of minor homologs of tRNA2
Lys and tRNA4
Lys were obtained. The distinctions between tRNA2
Lys and tRNA4
Lys may be part of significant cellular roles as illustrated by the differential effects of these isoacceptors on the synthesis by lysyl-tRNA synthetase of diadenosine-5,5-P1,P4-tetraphosphate, a putative signal in DNA replication. 相似文献
16.
Xanthophyll cycle and light stress in nature: uniform response to excess direct sunlight among higher plant species 总被引:73,自引:0,他引:73
Photosystem II (PS II) efficiency, nonphotochemical fluorescence quenching, and xanthophyll cycle composition were determined in situ in the natural environment at midday in (i) a range of differently angled sun leaves ofEuonymus kiautschovicus Loesener and (ii) in sun leaves of a wide range of different plant species, including trees, shrubs, and herbs. Very different degrees of light stress were experienced by these leaves (i) in response to different levels of incident photon flux densities at similar photosynthetic capacities amongEuonymus leaves and (ii) as a result of very different photosynthetic capacities among species at similar incident photon flux densities (that were equivalent to full sunlight). ForEuonymus as well as the interspecific comparison all data fell on one single, close relationship for changes in intrinsic PSII efficiency, nonphotochemical fluorescence quenching, or the levels of zeaxanthin + antheraxanthin in leaves, respectively, as a function of the actual level of light stress. Thus, the same conversion state of the xanthophyll cycle and the same level of energy dissipation were observed for a given degree of light stress independent of species or conditions causing the light stress. Since all increases in thermal energy dissipation were associated with increases in the levels of zeaxanthin + antheraxanthin in these leaves, there was thus no indication of any form of xanthophyll cycle-independent energy dissipation in any of the twenty-four species or varieties of plants examined in their natural environment. It is also concluded that transient diurnal changes in intrinsic PSII efficiency in nature are caused by changes in the efficiency with which excitation energy is delivered from the antennae to PSII centers, and are thus likely to be purely photoprotective. Consequently, the possibility of quantifying the allocation of absorbed light into PSII photochemistry versus energy dissipation in the antennae from changes in intrinsic PSII efficiency is explored.Abbreviations A
antheraxanthin
- F
actual level of fluorescence
- Fa, F
o
minimal fluorescence in the absence, presence of thylakoid energization
- Fm, F
m
maximal fluorescence in the absence, presence of thylakoid energization
- Fm, - F)/F
m
actual PSII efficiency ( = percent of absorbed light utilized in PSII photochemistry)
- Fv/Fm, F
v
/Fm/
PSII efficiency of open centers in the absence, presence of thylakoid energization
- NPQ
nonphotochemical fluorescence quenching
- Fm/F
m
- 1; qp
quenching coefficient for photochemical quenching
- V
violaxanthin
- Z
zeaxanthin 相似文献
17.
Hachiro Inokuchi Kazunori Kondo Masami Yoshimura Haruo Ozeki 《Molecular & general genetics : MGG》1990,223(3):433-437
Summary A UGA suppressor derived from a glutamine tRNA gene of Escherichia coli K 12 was isolated and characterized. Phages carrying the suppressor su+2UGA could be obtained only from a hybrid transducing phage, h
80
cI
857psu
+2oc, but not from the original transducing phage cI
857psu
+2oc. By DNA sequence analysis, it was found that the su
+2 UGA suppressor obtained has two mutations; one is in the anticodon (TTATCA), as expected, and the other (CT) is at the 7th position from the 3 end of tRNA
2
Gln
. The significance of these mutations and the lethal effect on phage of the increased amounts of UGA suppressor tRNAs are discussed. 相似文献
18.
19.
F. Weber-Lotfi L. Maréchal-Drouard O. Folkerts M. Hanson J. M. Grienenberger 《Plant molecular biology》1993,21(2):403-407
22 tRNA genes corresponding to 17 tRNA species were localized on the master circle of Petunia hybrida mitochondrial (mt) DNA. Genes for trnN, trnM, trnS-GGA, trnW and trnH are of the chloroplast-like type and presumably originate from promiscuous chloroplast (cp) DNA sequences inserted into the petunia mitochondrial genome. A comparison of the mt tRNAs or tRNA genes population present in two monocotyledonous plants (wheat and maize) and two dicotyledonous plants (petunia and potato) show slight differences in the genetic origin of individual tRNAs. The organization of the petunia mt tRNA genes as well as the number of tRNA gene copies, compared to other plant species, is discussed. 相似文献
20.
B. P. Kaine 《Journal of molecular evolution》1987,25(3):248-254
Summary Nucleotide sequences of four tRNA genes from the archaebacteriumSulfolobus solfataricus have been determined. Based upon DNA sequence analysis, three of the four genes contain presumptive intervening sequences (introns) in their anticodon loops. The three introns can form similar, but not identical, secondary structures. The cleavage site at the 3 end of all three introns occurs in a three-base bulge loop. All four genes lack an encoded 3 CCA terminus and are flanked by A+T-rich DNA sequences. Two of the genes are located on antiparallel DNA strands, with their 3 termini separated by 414 bp of sequence. Including two previously published sequences, a total of five introns have now been detected among sixS. solfataricus tRNA genes. Occurrence of introns at corresponding locations in both archaebacterial and eukaryotic tRNA genes suggests that the intron/exon form of gene structure predates the evolutionary divergence of the archaebacteria and the eukaryotes. 相似文献