ライフサイエンスコーパス: eIF1

1 eIF1 also mediates release of P site tRNA, whereas eIF3j

2 eIF1 and eIF1A are key players in assembly of 43S.mRNA c

3 eIF1 binds simultaneously to eIF4G and eIF3c in vitro, a

4 eIF1 interacts with the region (60-137) that immediately

5 eIF1 is a universally conserved translation factor that

6 eIF1 prevents the irreversible GTP hydrolysis that commi

7 eIF1 release in response to start codon recognition is a

8 Eukaryotic initiation factor 1 (eIF1) is a low molecular weight factor critical for stri

9 eukaryotic translation initiation factor 1 (eIF1), eIF1A, and eIF2beta all increase SUI1 expression

10 timulated by eukaryotic initiation factor 1 (eIF1), eIF1A, eIF3, and eIF5, and the resulting preiniti

11 tis elegans translation initiation factor 1 (eIF1).

12 und to eukaryotic initiation factor (eIF) 3, eIF1, eIF1A, and an eIF2/GTP/Met-tRNAi(Met) ternary comp

13 d eIF3 in the 40S preinitiation complex (40S.eIF1.eIF1A.eIF3.Met-tRNA(i).eIF2.GTP) and the subsequent

14 (93-97)ASQAA (abbreviated 93-97) accelerates eIF1 dissociation and P(i) release from reconstituted pr

15 Although eIF1 and eIF1A promote scanning, eIF1 and possibly the C

16 Although eIF1 autoregulates by discriminating against poor contex

17 F1 on the 40S subunit suggests that although eIF1 is unable to inspect the region of initiation codon

18 formation of this cap-proximal complex, and eIF1 weakly promotes formation of a 48S ribosomal comple

19 so a marked reduction in 40 S-bound eIF2 and eIF1, consistent with an important role for RLI1 in asse

20 Therefore eIF3 and eIF1 dissociate from 40S subunits during, rather than be

21 anonical initiation factors except eIF4E and eIF1.

22 -1 reduced the interaction between eIF4G and eIF1 in vitro.

23 lso reduces the levels of 40S-bound eIF5 and eIF1 and increases leaky scanning at the GCN4 uORF1.

24 on with the AUG recognition factors eIF5 and eIF1.

25 us of NIP1 can bind concurrently to eIF5 and eIF1.

26 The eIF2, eIF5, and eIF1 all have been implicated in stringent selection of

27 (MFC), comprised of these three factors and eIF1, supporting a mechanism of coupled 40S binding by M

28 that closes upon start codon recognition and eIF1 release to stabilize ternary complex binding and cl

29 hich justifies the possibility that YciH and eIF1 might have a common evolutionary origin as initiati

30 le for the factor's activity in antagonizing eIF1 binding to the PIC.

31 hat ribosomes are three times as abundant as eIF1, eIF2 and eIF5, while eIF3 is half as abundant as t

32 The direct interaction at eIF1-KH also places eIF5 near the decoding site of the 4

33 F1 exacerbated the tif5-7A phenotype because eIF1 forms unusual inhibitory complexes with a hyperstoi

34 NIP1-NTD coordinates an interaction between eIF1 and eIF5 that inhibits GTP hydrolysis at non-AUG co

35 g the core of the platform domain that binds eIF1 and eIF2, and A1193U, changing the h31 loop located

36 complex contained, in addition to eIF3, both eIF1 and eIF1A in a 1:1 stoichiometry with respect to th

37 mplex was stabilized by the presence of both eIF1 and eIF3.

38 These studies demonstrate that both eIF1 and eIF1A are capable of binding to the 40S subunit

39 ined 3D reconstructions of 40S bound to both eIF1 and eIF1A, and with each factor alone.

40 -tRNA(iMet) recruitment were destabilized by eIF1, dissociation of 48S complexes formed with eIF2 cou

41 renders them susceptible to dissociation by eIF1.

42 s, after which tRNA and mRNA are released by eIF1/eIF1A, Ligatin, or MCT-1/DENR.

43 ces PIC assembly, but in a manner rescued by eIF1.

44 s Gcd(-) phenotype is likewise suppressed by eIF1 overexpression or the 17-21 mutation.

45 cts of this NIP1 mutation were suppressed by eIF1 overexpression, as was the Sui(-) phenotype conferr

46 ues affected by the Saccharomyces cerevisiae eIF1 mutations are also localized.

47 Sui(-) mutations in Saccharomyces cerevisiae eIF1, which increase initiation at UUG codons, reduce in

48 implicated in the yeast multifactor complex (eIF1-eIF3-eIF5-eIF2-GTP-Met-tRNA(i)(Met)).

49 stable multifactor complex (MFC) comprising eIF1, eIF2, eIF3 and eIF5, similar to the MFC reported i

50 stoichiometric quaternary complex containing eIF1 and the minimal segments of eIF2beta, eIF3c, and eI

51 stabilize the multifactor complex containing eIF1, eIF3, eIF5, and TC, showing that eIF1 promotes PIC

52 Eukaryotic initiation factor (eIF) eIF1 maintains the fidelity of initiation codon selectio

53 were identified previously, including eIF1A, eIF1, eIF2, and eIF5.

54 eIF2, eIF3, eIF1 and eIF1A promote efficient 48S initiation complex

55 The presence of eIF2, eIF3, eIF1, eIF1A, and Met-tRNAi(Met) was sufficient for recyc

56 can be mediated by initiation factors eIF3, eIF1, and eIF1A, this energy-free mechanism can function

57 don and report that initiation factors eIF3, eIF1, eIF1A, and eIF3j, a loosely associated subunit of

58 initiation factors in vitro, including eIF3, eIF1, eIF5, and eIF1A.

59 The TC, eIF3, eIF1, and eIF1A cooperatively bind to the 40S subunit, y

60 In cooperation with eIF3, eIF1, and eIF1A, Met-tRNA(Met)(i)/eIF2/GTP binds to 40S

61 et) ternary complex (TC) interacts with eIF3-eIF1-eIF5 complex to form the multifactor complex (MFC),

62 rm the 40 S preinitiation complex (40 S.eIF3.eIF1.eIF1A.Met-tRNA(i).eIF2.GTP).

63 e findings suggest the occurrence of an eIF3/eIF1/eIF5/eIF2 multifactor complex, which was observed i

64 D) bridges interaction between eIF2 and eIF3/eIF1 in a multifactor complex containing Met-tRNA(i)(Met

65 (i)(Met) ternary complex (TC) binds the eIF3/eIF1/eIF5 complex to form the multifactor complex (MFC),

66 eIF5, eIF1 and HCR1 co-purified with this subcomplex, but not

67 f eIF2beta bind three common partners, eIF5, eIF1, and mRNA.

68 it binds to, and stabilizes, the eIF3-eIF5- eIF1-eIF2 multifactor complex and is required for the no

69 tion of a stress-inducible cDNA that encodes eIF1 suggests that modulation of translation initiation

70 in other eukaryotes, the yeast gene encoding eIF1 (SUI1) contains an AUG in poor context, which could

71 esidues that are identical in all eukaryotic eIF1 proteins.

72 In addition, excess eIF1 inhibits growth of a second eIF4G mutant defective

73 Interestingly, excess eIF1 carrying the sui1-1 mutation, known to relax the ac

74 Eukaryotic initiation factor eIF1 and the functional C-terminal domain of prokaryotic

75 the role of the mammalian initiation factor eIF1 in the formation of the 40 S preinitiation complex

76 ologous to the translation initiation factor eIF1/SUI1; these proteins may comprise a novel type of t

77 show that the presence of initiation factors eIF1, eIF1A and eIF3 in the 40S preinitiation complex (4

78 Two eukaryotic initiation factors, eIF1 and eIF1A, are key actors in this process.

79 s involves the binding of two small factors, eIF1 and eIF1A, to the small (40S) ribosomal subunit.

80 Nevertheless, both forms of FLAG-eIF1 fail to bind eIF3 and are incorporated into the 43

81 Furthermore, N-terminal FLAG-eIF1 overexpression reduces eIF2 binding to the ribosome

82 is lethal; overexpression of C-terminal FLAG-eIF1 severely impedes 43 S complex formation and derepre

83 hese studies suggest that it is possible for eIF1 and eIF1A to bind the 40 S preinitiation complex pr

84 ic/acidic boxes), that the binding sites for eIF1 and eIF3c are located in a conserved surface region

85 odon selection during 48S complex formation, eIF1 also participates in maintaining the fidelity of th

86 This interaction explains how eIF1 is recruited to the 40S ribosomal subunit.

87 To understand how eIF1 plays its discriminatory role, we determined its po

88 Human eIF1 and eIF1A bind cooperatively to the 40 S subunit, r

89 e determined the solution structure of human eIF1 with an N-terminal His tag using NMR spectroscopy.

90 partial sequence of recently purified human eIF1.

91 We also show that like IF3, eIF1 can influence initiator tRNA selection, which occur

92 by an eIF1A mutation (17-21) known to impede eIF1 dissociation in vitro.

93 omplex revealed several basic amino acids in eIF1 contacting 18 S rRNA, and we tested the prediction

94 at the SUI1 AUG, whereas Ssu(-) mutations in eIF1 and eIF1A decrease SUI1 expression with the native,

95 We also describe Gcd(-) mutations in eIF1 that impair TC loading on 40S subunits or destabili

96 ion (Sui(-) phenotype) by allowing increased eIF1 release at non-AUG codons.

97 Interestingly, eIF1-KH includes the altered hydrophobic residues.

98 eIF1A enhances the ability of eIF1 to dissociate aberrantly assembled complexes from m

99 is process and report that in the absence of eIF1 and DHX29, eIFs 4A, 4B and 4G promote efficient byp

100 In the absence of eIF1, 43S complexes could no longer discriminate between

101 In the absence of eIF1, eIF5-stimulated hydrolysis of eIF2-bound GTP occur

102 eIF3 dramatically increases the affinity of eIF1 and eIF3j for the 40 S subunit.

103 uitment of TC also increases the affinity of eIF1 for the 40 S subunit, but this interaction has an i

104 py to systematically measure the affinity of eIF1, eIF1A, and eIF3j in the presence of different comb

105 mplexes with a hyperstoichiometric amount of eIF1.

106 The stable association of eIF1 with 40 S subunits required the presence of eIF3.

107 in multiple segments reduced the binding of eIF1 or eIF5 to the NIP1-NTD.

108 Together, our data indicate that binding of eIF1 to the c/Nip1-NTD is equally important for its init

109 e also show that eIF5 antagonizes binding of eIF1 to the complex and that key interactions of eIF1 wi

110 Mutations that weaken binding of eIF1 to the PIC decrease the fidelity of start codon rec

111 ween the binding of eIF3j and the binding of eIF1, eIF1A, and TC with the 40 S subunit.

112 se findings indicate that direct contacts of eIF1 with 18 S rRNA seen in the Tetrahymena 40 S.eIF1 co

113 However, the contributions of eIF1, eIF1A, eIF3, and the eIF2-GTP-Met-tRNAi ternary co

114 that AUG recognition evokes dissociation of eIF1 from its 40S binding site, ejection of the eIF1A-CT

115 codon is thought to require dissociation of eIF1 from the 40 S ribosomal subunit, enabling irreversi

116 rrests scanning and promotes dissociation of eIF1 from the 40S subunit.

117 this movement is coupled to dissociation of eIF1 from the PIC, a critical event in start codon recog

118 Dissociation of eIF1 from the preinitiation complex (PIC) allows release

119 trolled by the AUG-dependent dissociation of eIF1 from the preinitiation complex.

120 in gating phosphate release, dissociation of eIF1 triggers conversion from an open, scanning-competen

121 Although the ribosome-binding face of eIF1 was identified, interfaces to other preinitiation c

122 tiation at UUG codons, reduce interaction of eIF1 with 40S subunits in vitro and in vivo, and both de

123 to the complex and that key interactions of eIF1 with its partners are modulated by the charge at an

124 These structures reveal the locations of eIF1, eIF1A, mRNA and initiator transfer RNA bound to th

125 very favorable for an indirect mechanism of eIF1's action by influencing the conformation of the pla

126 reduced approximately 5-fold on omission of eIF1 and eIF1A.

127 By contrast, overexpression of eIF1 exacerbated the tif5-7A phenotype because eIF1 form

128 In vivo, co-overexpression of eIF1 or eIF5 reverses the genetic suppression of an eIF4

129 Overexpression of eIF1, which is thought to monitor codon-anticodon intera

130 A mutation altering the basic part of eIF1-KH is lethal and shows a dominant phenotype indicat

131 xcellent candidate for the direct partner of eIF1-KH that mediates the critical link.

132 The position of eIF1 on the 40S subunit suggests that although eIF1 is u

133 Unexpectedly, the position of eIF1 on the 40S subunit was strikingly similar to the po

134 lated region (5'-UTR) and in the presence of eIF1 scan along it and locate the initiation codon witho

135 -) phenotypes without increasing the rate of eIF1 release.

136 propose that the coordinated recruitment of eIF1 to the 40 S ribosome in the MFC is critical for the

137 ons that eIF3 is required for recruitment of eIF1 to the small ribosomal subunit.

138 Our results also suggest that release of eIF1 from the PIC and movement of the CTT of eIF1A are t

139 ts in a conformational change and release of eIF1 from the ribosome.

140 d assists the start codon-induced release of eIF1, the major antagonist of establishing tRNA(i)(Met):

141 ined mutations at the penultimate residue of eIF1, G107, that produce Sui(-) phenotypes without incre

142 at the alteration of hydrophobic residues of eIF1 disrupts a critical link to the preinitiation compl

143 l tail of eIF1A, changes in the structure of eIF1 likely instrumental in its subsequent release, and

144 ethered to seven positions on the surface of eIF1 places eIF1 on the interface surface of the platfor

145 Here we show that FLAG epitope tagging of eIF1 at either terminus abolishes its in vitro interacti

146 C-terminal FLAG tagging of eIF1 is lethal; overexpression of C-terminal FLAG-eIF1 s

147 mplicate the unstructured N-terminal tail of eIF1 in blocking rearrangement to the closed conformatio

148 One domain has the fold similar to that of eIF1, which is crucial for the scanning and initiation c

149 o retrograde scanning, strongly dependent on eIF1 and eIF1A.

150 is induction of AIRAP is solely dependent on eIF1 and the uORF kozak context.

151 s led to release of eIF2-GDP but not eIF3 or eIF1.

152 one deacetylase 2B but did not phosphorylate eIF1, eIF1A, eIF4A, eIF4E, eIF4G, eIFiso4E, or eIFiso4G.

153 even positions on the surface of eIF1 places eIF1 on the interface surface of the platform of the 40S

154 yeast eIF1 are required to prevent premature eIF1 dissociation from scanning ribosomes at non-AUG tri

155 and mammals, this mechanism does not prevent eIF1 overproduction in yeast, accounting for the hyperac

156 Previously, eIF1 mutations were identified that increase initiation

157 YciH, a prokaryotic eIF1 homologue, could perform some of IF3's functions, w

158 poor context of the eIF1 AUG codon to reduce eIF1 abundance.

159 codon base-pairing in 48S complexes relieved eIF1's inhibition.

160 es not involve scanning and does not require eIF1, eIF1A, and the eIF4E subunit of eIF4F.

161 rnary complex to 40 S subunits also required eIF1.

162 The resulting complex requires eIF1, eIF1A, eIF4A, eIF4B and eIF4F to bind to a messeng

163 rough dVI to the initiation codon, requiring eIF1 to bypass its AUG.

164 with 18 S rRNA seen in the Tetrahymena 40 S.eIF1 complex are crucial in yeast to stabilize the open

165 The crystal structure of a Tetrahymena 40 S.eIF1 complex revealed several basic amino acids in eIF1

166 hat in addition to its function in scanning, eIF1 also plays a principal role in initiation codon sel

167 Although eIF1 and eIF1A promote scanning, eIF1 and possibly the C-terminal tail of eIF1A must be d

168 Overexpressing the NIP1-NTD sequestered eIF1-eIF5-eIF2 in a defective subcomplex that derepresse

169 (PIC) containing the 40S ribosomal subunit, eIF1, eIF1A, eIF3, ternary complex (eIF2-GTP-Met-tRNAi),

170 to the preinitiation complex that suppresses eIF1 release before start codon selection.

171 These findings demonstrate that eIF1 dissociation is a critical step in start codon sele

172 ults provide the first in vivo evidence that eIF1 plays an important role in promoting 43 S complex f

173 We hypothesize that eIF1 acts by antagonizing conformational changes that oc

174 The data further indicate that eIF1 dissociation must be accompanied by the movement of

175 Our data indicate that eIF1 plays multiple roles in start codon recognition and

176 This indicates that eIF1 and eIF1A communicate with one another when bound t

177 Here we report that eIF1 and eIF1A are also both essential for translation i

178 NMR, but GST pull-down experiments show that eIF1 binds specifically to the p110 subunit of eIF3.

179 We show that eIF1 is phosphorylated under specific conditions that in

180 ining eIF1, eIF3, eIF5, and TC, showing that eIF1 promotes PIC assembly in vivo beyond its important

181 Our results suggest that eIF1 and eIF1A promote an open, scanning-competent prein

182 These results support that eIF1 functions in ensuring the fidelity of AUG start cod

183 It is thought that eIF1 prevents recognition of non-AUGs by promoting scann

184 The eIF1 Sui(-) mutations also derepress translation of GCN4

185 ressed the Sui(-) phenotypes produced by the eIF1-D83G and eIF5-G31R mutations.

186 t suppresses Sui(-) mutations) decreases the eIF1 off-rate.

187 eps in translation initiation, including the eIF1- and eIF1A-dependent delivery of initiator methiony

188 acerbating the effect of poor context of the eIF1 AUG codon to reduce eIF1 abundance.

189 ic and biochemical studies indicate that the eIF1 N-terminal tail plays a stimulatory role in coopera

190 racy of initiation codon selection belong to eIF1 and eIF1A, whereas the mammalian-specific DHX29 hel

191 Nip1 subunit, which mediates eIF3 binding to eIF1 and eIF5, to semirandom mutagenesis to investigate

192 that the binding of the eIF4G HEAT domain to eIF1 and eIF5 is important for maintaining the integrity

193 /eIF3- and eIF5B/eIF3-mediated mechanisms to eIF1-induced destabilization.

194 th initiator tRNA in the PIN state, prior to eIF1 release.

195 on complex components and their relevance to eIF1 function have not been determined.

196 These structures reveal that together, eIF1 and eIF1A stabilize a conformational change that op

197 P hydrolysis in 43S complexes assembled with eIF1 was much slower than in 43S or 48S complexes assemb

198 bunits, eliminating functional coupling with eIF1.

199 (NTD) of NIP1/eIF3c interacts directly with eIF1 and eIF5 and indirectly through eIF5 with the eIF2-

200 its C-terminal HEAT domain to interact with eIF1, eIF2, and eIF3 in the multifactor complex and with

201 (NIP1-NTD and TIF32-CTD) that interact with eIF1, eIF5, and the eIF2/GTP/Met-tRNA(i)(Met) ternary co

202 2-mediated increase in eIF5 interaction with eIF1 and eIF3c in pulldown assays and reduces the eIF5-m

203 tic initiation factor (eIF) 5 interacts with eIF1, eIF2beta, and eIF3c, thereby mediating formation o

204 eIF3) forms a multifactor complex (MFC) with eIF1, eIF2, and eIF5 that stimulates Met-tRNA(i)(Met) bi

205 ractions of NIP1 with PRT1 and of TIF32 with eIF1.

206 an in 43S or 48S complexes assembled without eIF1.

207 Yeast eIF1 inhibits initiation at non-AUG triplets, but it was

208 prediction that their counterparts in yeast eIF1 are required to prevent premature eIF1 dissociation

209 eta-hairpin loop-1, impairs binding of yeast eIF1 to 40 S.eIF1A complexes in vitro, and it confers in

210 Exploiting the solution structure of yeast eIF1, here we locate the binding site for eIF5 in its N-