ライフサイエンスコーパス: initiator tRNA

1 idelity-determining regions that contact the initiator tRNA.

2 he small ribosomal subunit from elongator to initiator tRNA.

3 on-AUG-related codon, without involvement of initiator tRNA.

4 2:71 base pairs in the acceptor stem of the initiator tRNA.

5 for formylation in the acceptor stem of the initiator tRNA.

6 irs 50:64 and 51:63 in the TpsiC stem of the initiator tRNA.

7 clustered mostly in the acceptor stem of the initiator tRNA.

8 mportant role in specific recognition of the initiator tRNA.

9 fically the binding affinity of eIF2 for the initiator tRNA.

10 nd hypermodified t6A at nucleotide 37 of the initiator tRNA.

11 in contact with the ternary complex eIF2.GTP.initiator tRNA.

12 onas aeruginosa bound to compact IF2-GDP and initiator tRNA.

13 romotes dissociation by dismissing the bound initiator tRNA.

14 C base (3G-C) pairs in the anticodon stem of initiator tRNA.

15 nd therefore 80S-like ribosomes lack mRNA or initiator tRNA.

16 bit translation by site-specific cleavage of initiator tRNA.

17 e codon on the mRNA and the anticodon of the initiator tRNA.

18 the anticodon stem-loop of the P site-bound initiator tRNA.

19 the 30S subunit for optimal interaction with initiator tRNA.

20 ribosomal subunits, between the platform and initiator tRNA.

21 em sequences are most divergent from that of initiator tRNA.

22 absence of canonical initiation factors and initiator tRNA.

23 ere synthesized in the absence of formylated initiator tRNA.

24 in the presence of the corresponding mutant initiator tRNAs.

25 e primary negative determinant in eukaryotic initiator tRNAs.

26 ion initiation is a complex process in which initiator tRNA, 40S, and 60S ribosomal subunits are asse

27 in the presence of the corresponding mutant initiator tRNAs, AGG and GUC can initiate protein synthe

28 Here we show that E. coli initiator tRNA also has a secondary negative determinant

29 In eukaryotic systems, however, a yeast initiator tRNA aminoacylated with isoleucine was found t

30 ing a 5-fold increase in the value of Km for initiator tRNA and a 100-fold decrease in Vmax in puromy

31 don stem are a key discriminatory feature of initiator tRNA and are required for its selection by IF3

32 ors (IFs) 1, 2, and 3 mediate the binding of initiator tRNA and mRNA to the small ribosomal subunit t

33 de evidence that the interaction between the initiator tRNA and the 30S P site is tuned to balance ef

34 on factors (IFs 1-3) enable the selection of initiator tRNA and the start codon in the P site of the

35 ation of translation is the process by which initiator tRNA and the start codon of mRNA are positione

36 s with the 30S ribosome binding first to the initiator tRNA and then to the mRNA.

37 tRNAs, most ribosomes would carry the mutant initiator tRNA and these ribosomes would select the muta

38 table owing to dissociation of eIF2*GDP from initiator tRNA, and eIF5B is then required to stabilize

39 n substantially pure form, free of the yeast initiator tRNA, and have analyzed their properties in vi

40 ure reveals conformational changes in eIF5B, initiator tRNA, and the ribosome that provide insights i

41 s are identical, our findings with the human initiator tRNA are likely to be valid for all vertebrate

42 how that both the wild-type and mutant human initiator tRNAs are aminoacylated well in vivo.

43 Because the sequences of all vertebrate initiator tRNAs are identical, our findings with the hum

44 The anticodon stem-loops of initiator tRNAs are more likely to be distinguished from

45 Initiator tRNAs are special in their direct binding to t

46 Initiator tRNAs are used exclusively for initiation of p

47 Initiator tRNAs are used exclusively for initiation of p

48 2L mutant enzymes using acceptor stem mutant initiator tRNAs as substrates suggest that arginine 42 m

49 The mechanism by which IF2 separates from initiator tRNA at the end of translation initiation rema

50 ate utilization of non-AUG codons and mutant initiator tRNAs at initiation.

51 initiation was independent of the canonical initiator tRNA (AUG/Met-tRNA(i)(Met)) pathway but requir

52 nal tail (CTT) of Rps16, believed to contact initiator tRNA base-paired to AUG in the P site.

53 nism of communication between the GTPase and initiator tRNA binding domains that has been proposed fo

54 AFs Tsr1 and Rio2 block the mRNA channel and initiator tRNA binding site, and therefore 80S-like ribo

55 model for controlled nucleotide exchange and initiator tRNA binding to the eIF2/eIF2B complex.

56 a complementary role, selectively promoting initiator tRNA binding to the ribosome.

57 to ribosomes even though it does not promote initiator-tRNA binding.

58 lves the assembly of a ribosome complex with initiator tRNA bound to the peptidyl site and paired to

59 stable complex with the protein, whereas the initiator tRNA bound transiently.

60 bacterial synthetase aminoacylates mammalian initiator tRNA, but not elongator tRNA.

61 e molecular mechanisms of recognition of the initiator tRNA by Escherichia coli MTF.

62 S subunits and the preferential selection of initiator tRNA by IF3 during initiation.

63 he molecular mechanism of recognition of the initiator tRNA by MTF, we report here on the isolation a

64 icodon sequence mutant of Haloferax volcanii initiator tRNA can initiate Bop protein synthesis using

65 her anticodon sequence mutant of an archaeal initiator tRNA can initiate protein synthesis using repo

66 This mutant initiator tRNA can, however, be aminoacylated in vitro b

67 on of the second ORF and mutant elongator or initiator tRNAs capable of reading these codons, we prov

68 , the activity in elongation of mutant human initiator tRNAs carrying anticodon sequence mutations fr

69 itiation of protein translation (delivery of initiator tRNA charged with methionine to the ribosome).

70 ion factor 3 (eIF3), and a ternary [eIF2-GTP-initiator tRNA] complex) binds the IRES in a precise man

71 uss the potential applications of the mutant initiator tRNA-dependent initiation of protein synthesis

72 chanism, which is conceptually distinct from initiator tRNA-dependent mechanisms.

73 ssociation of both eIF3 and eIF2, preventing initiator tRNA deposition and explaining the block in 80

74 During eukaryotic translation initiation, initiator tRNA does not insert fully into the P decoding

75 eraction between the AUG start codon and the initiator-tRNA during the ribosomal scanning process.

76 ome as part of a ternary complex composed of initiator tRNA, eIF2, and GTP.

77 e tRNA may serve to ensure that only charged initiator tRNA enters the initiation pathway.

78 ity for mRNA is restored upon recruitment of initiator tRNA, even though eIF3j remains in the mRNA-bi

79 (M) and k(cat) for aminoacylation of E. coli initiator tRNA(f)(Met) are reported.

80 the characteristic C(+1)/A(+72) base pair of initiator tRNA(f-met) as the sole determinant of slow RN

81 Second, the models reconcile how initiator tRNA(fMet) interacts less strongly with the L1

82 f nascent proteins using an Escherichia coli initiator tRNA(fmet) misaminoacylated with methionine mo

83 The 70SIC contains initiator tRNA, fMet-tRNA(fMet), bound in the P (peptidy

84 of IF2 or increasing the affinity of mutant initiator tRNA for IF2 enhanced re-initiation efficiency

85 ith an amber suppressor derived from E. coli initiator tRNA, for use in E. coli.

86 with an amber suppressor derived from human initiator tRNA, for use in yeast, and mutants of the yea

87 that two of the unique properties of E. coli initiator tRNA - formylation of the amino acid attached

88 ary sequence feature that prevents the human initiator tRNA from acting in the elongation step is the

89 y this process, we have cloned the wild type initiator tRNA gene from the moderate halophilic archaeb

90 n our laboratory for expression of the human initiator tRNA gene in yeasts.

91 In vivo, increasing the dose of the yeast initiator tRNA gene suppressed the slow-growth phenotype

92 formation with a plasmid carrying the mutant initiator tRNA gene, only strains designed to maintain t

93 ow that both Escherichia coli and eukaryotic initiator tRNAs have negative determinants, at the same

94 Using Escherichia coli, we show that initiator tRNA (i-tRNA), specifically the evolutionarily

95 hermophilus 70S ribosome in complex with the initiator tRNA(i)(fMet) and a short mRNA.

96 unction with the 40 S ribosomal subunit and (initiator) tRNA(i).

97 is critical for specific recognition of the initiator tRNA in Escherichia coli.

98 he 40S subunit and the positions of mRNA and initiator tRNA in initiation complexes.

99 s important for activity of Escherichia coli initiator tRNA in initiation.

100 ir is to orient the methionine moiety on the initiator tRNA in its recognition pocket on eIF2.

101 ifferent anticodon sequence mutants of human initiator tRNA in mammalian COS1 cells, using reporter g

102 A modification is essential for stability of initiator tRNA in Saccharomyces cerevisiae.

103 volves recognition of the start codon by the initiator tRNA in the 30S subunit.

104 t interacts only weakly with GTP or with the initiator tRNA in the absence of ribosomes.

105 and eIF5B is then required to stabilize the initiator tRNA in the P site of 40S subunit.

106 einitiation complex at 4.0 A resolution with initiator tRNA in the PIN state, prior to eIF1 release.

107 by the placement of the AUG start codon and initiator tRNA in the ribosomal peptidyl (P) site.

108 ing that the poor activity of unconventional initiator tRNAs in E. coli is because of competition fro

109 have isolated the wild-type and mutant human initiator tRNAs in substantially pure form, free of the

110 unctional studies of mutant Escherichia coli initiator tRNAs in vivo, we previously described a strat

111 eads to dissociation of eIF-2 x GDP from the initiator-tRNA in the 43S preinitiation complex serves a

112 h a higher rate of dissociation from charged initiator-tRNA in the absence of GTP hydrolysis.

113 This may reflect the rapid charging of the initiator tRNA, in contrast to the elongator tRNA, which

114 eatures resembling those of Escherichia coli initiator tRNA, including standard dihydrouridine and T

115 is similar to that observed with the intact initiator tRNA, indicating that the inhibition is substr

116 und ribosomes are also strongly enriched for initiator tRNA, indicating they are associated with earl

117 ticodon sequence mutants of Escherichia coli initiator tRNA initiate protein synthesis with codons ot

118 rect single-molecule tracking, the timing of initiator tRNA, initiation factor 2 (IF2; encoded by inf

119 ppressor tRNAs derived from Escherichia coli initiator tRNA into mammalian COS1 cells, and we present

120 itiation factors involved in introducing the initiator tRNA into the translation mechanism and perfor

121 Analysis of tRNAs in vivo show that the initiator tRNA is aminoacylated but is not formylated in

122 The role of formylation of the initiator tRNA is not known, but in vitro formylation in

123 prisingly, under conditions where the mutant initiator tRNA is optimally active, the CAT gene with th

124 The primary negative determinant in E. coli initiator tRNA is the C1xA72 mismatch at the end of the

125 Of all tRNAs, initiator tRNA is unique in its ability to start protein

126 The initiator tRNA is usually recruited to the ribosome as p

127 e primary negative determinant in eukaryotic initiator tRNAs is located in the TPsiC stem, whereas a

128 RNA(fMet) , we have engineered an orthogonal initiator tRNA (itRNA(Ty2) ) that is a substrate for Met

129 We show that E. coli can be sustained on an initiator tRNA lacking the first and third G-C pairs; th

130 Given this, the occurrence of unconventional initiator tRNAs lacking the 3G-C pairs, as in some speci

131 nsate for the formylation defect of a mutant initiator tRNA, lacking a critical determinant in the ac

132 smatch, unique to eubacterial and organellar initiator tRNAs, may also be important for the binding o

133 F1A with dual functions in binding methionyl initiator tRNA (Met-tRNA(i)(Met)) to the ribosome and in

134 ts GTP-bound state it delivers the methionyl initiator tRNA (Met-tRNA(i)) to the small ribosomal subu

135 with ribosomal recruitment of aminoacylated initiator tRNA (Met-tRNA(Met)(i)) by eukaryotic initiati

136 ic mRNAs depends on recruitment of methionyl initiator tRNA (Met-tRNAi) in a ternary complex (TC) wit

137 absence of canonical initiation factors and initiator tRNA (Met-tRNAi), occupy the ribosomal P-site

138 cid-starved cells involves the inhibition of initiator tRNA(Met) binding to eukaryotic translation in

139 ion in translation initiation at the step of initiator tRNA(Met) binding to the ribosome.

140 own to lower the amounts of ternary eIF2-GTP/initiator tRNA(met) complexes.

141 ces: the nusA operon, including the complete initiator tRNA(Met) gene, metY; a tRNA(Leu) gene; the tp

142 e eIF2 kinase GCN2 or in cells that have two initiator tRNA(met) genes disrupted.

143 4 overexpression did not diminish functional initiator tRNA(Met) levels.

144 P-tRNA(i)Met, the ternary complex that joins initiator tRNA(Met) to the 43S preinitiation complex.

145 erotrimeric protein that transfers methionyl-initiator tRNA(Met) to the small ribosomal subunit in a

146 in S. cerevisiae in the absence of eIF2 and initiator tRNA(met), by the same mechanism of factor-ind

147 tRNA fragments including those derived from initiator-tRNA(Met).

148 2alpha, the translation factor that recruits initiator tRNA-Meti for general translation, is observed

149 hamper its ability to interact with incoming initiator tRNA molecules.

150 In cells overproducing the mutant initiator tRNAs, most ribosomes would carry the mutant i

151 of the complex of bacterial 30S subunit with initiator tRNA, mRNA, and IFs 1-3, representing differen

152 y understood if assembly of the 30S ribosome-initiator tRNA-mRNA initiation complex in vivo proceeds

153 ses the in vivo amber suppressor activity of initiator tRNA mutants that have changes in the acceptor

154 CAU-->GAC) in the anticodon sequence of the initiator tRNA on its recognition by the aminoacyl-tRNA

155 IF2 is a GTPase that positions the initiator tRNA on the 30S ribosomal initiation complex a

156 IF2 on the ribosome required to position the initiator tRNA on the mRNA in the ribosomal peptidyl-tRN

157 the simple reaction of 70 S ribosomes using initiator-tRNA or N-protected CCA-Phe as a P-site substr

158 tochondrial ribosomes in the absence of GTP, initiator tRNA, or messenger RNA.

159 culminates in a ribosome positioned with an initiator tRNA over the start codon and, thus, ready to

160 IF2, in the presence of sufficient levels of initiator tRNA, overcome the requirement for eIF2B in vi

161 gh affinity of IF2 for both 30 S subunit and initiator tRNA overrides any perturbation of the codon-a

162 dance of an IF3-independent step, presumably initiator tRNA positioning.

163 ition from a large pool of the endogenous WT initiator tRNA (possessing the 3G-C pairs).

164 IF3 stems primarily from its interplay with initiator tRNA rather than its anti-subunit association

165 Some mRNA-ribosome-initiator tRNA reactions that yielded weak or no toeprin

166 Although initiator tRNA recruitment was originally ascribed to an

167 o play an important role in the mechanism of initiator tRNA release upon initiation codon recognition

168 it, eukaryotic initiation factors (eIFs) and initiator tRNA scans mRNA to find an appropriate start c

169 The mechanisms of initiation codon and initiator tRNA selection in prokaryotes and eukaryotes a

170 Our model suggests that IF3 influences initiator tRNA selection indirectly.

171 also show that like IF3, eIF1 can influence initiator tRNA selection, which occurs at the stage of r

172 bition of initiation on leaderless mRNA, and initiator-tRNA selection, thereby establishing a direct

173 -codon discrimination, mRNA translation, and initiator-tRNA selection.

174 eatures resembling those of Escherichia coli initiator tRNA(t-Met).

175 ticodon sequence mutants of Escherichia coli initiator tRNAs that carry formylmethionine (fMet), form

176 y, in the presence of initiation factors and initiator tRNA, the association kinetics of structured m

177 nism involving neither initiation factor nor initiator tRNA, the CrPV IRES jumpstarts translation in

178 determinants for formylation present in the initiator tRNA, the nature of the amino acid attached to

179 h requires GTP but not the AUG codon to bind initiator tRNA to 40 S subunits.

180 changed the A1 x U72 base pair of the human initiator tRNA to G1 x C72 and expressed the wild-type a

181 g the binding of fluorescent nucleotides and initiator tRNA to purified eIF2 we show that the eIF2bet

182 tein synthesis translation factor eIF2 binds initiator tRNA to ribosomes and facilitates start codon

183 IF2 (p-eIF2alpha), which reduces delivery of initiator tRNA to ribosomes.

184 ranslation initiation factor that brings the initiator tRNA to the 40S ribosome.

185 methionine attached to the yeast cytoplasmic initiator tRNA to the extent of about 70%.

186 eIF2 guides the initiator tRNA to the ribosome, participates in scanning

187 rimer required for GTP-dependent delivery of initiator tRNA to the ribosome.

188 Protein synthesis factor eIF2 delivers initiator tRNA to the ribosome.

189 on initiation as it selects and delivers the initiator tRNA to the small ribosomal subunit.

190 ivo and promotes the binding of unformylated initiator tRNA to yeast mIF2.

191 ich is conserved in virtually all eukaryotic initiator tRNAs, to G1:C72 in the C35 mutant background

192 em and in the dihydrouridine (D) stem of the initiator tRNA (tRNA(fMet)).

193 n, as well as with a synthetic mitochondrial initiator tRNA (tRNA(Met)(f)).

194 A-starting codons, including the eukaryotic initiator tRNA (tRNAi (Met)).

195 Eukaryotic initiator tRNA (tRNAi) contains several highly conserved

196 coli ribosome to initiate translation for 31 initiator tRNA (tRNAini) anticodon mutants at their resp

197 attempts to convert an elongator tRNA to an initiator tRNA, we previously generated a mutant elongat

198 the Mi:2 tRNA to those found in the E. coli initiator tRNA, we show that change of the U4:A69 base p

199 With this reporter and mutant initiator tRNAs, we show that two of the unique properti

200 out the involvement of initiation factors or initiator tRNA were active in elongation and are, theref

201 aryotes requires a 40 S ribosome loaded with initiator tRNA which scans for an initiation codon.

202 ugar phosphate backbone in the TpsiC stem of initiator tRNA, which most likely blocks binding of the

203 A mutant initiator tRNA with compensating anticodon mutations res

204 sistent with the hypothesis, a plasmid-borne initiator tRNA with one, two, or all 3G-C pairs mutated

205 The combination of mutant initiator tRNA with the CCU anticodon and the reporter s

206 nhance interaction of the negatively charged initiator tRNA with the ribosome when the tRNA is base-p

207 two domains of IF3 on opposite sides of the initiator tRNA, with the C domain at the platform interf