Allele mining in the pepper gene pool provided new complementation effects between pvr2-eIF4E and pvr6-eIF(iso)4E alleles for resistance to pepper veinal mottle virus

Molecular cloning of recessive resistance genes to potyviruses in a large range of host species identified the eukaryotic translation initiation factor 4E (eIF4E) as an essential determinant in the outcome of potyvirus infection. Resistance results from a few amino acid changes in the eIF4E protein encoded by the recessive resistance allele that disrupt the direct interaction with the potyviral protein VPg. In plants, several loci encode two protein subfamilies, eIF4E and eIF(iso)4E. While most eIF4E-mediated resistance to potyviruses depends on mutations in a single eIF4E protein, simultaneous mutations in eIF4E (corresponding to the pvr2 locus) and eIF(iso)4E (corresponding to the pvr6 locus) are required to prevent pepper veinal mottle virus (PVMV) infection in pepper. We used this model to look for additional alleles at the pvr2-eIF4E locus that result in resistance when combined with the pvr6-eIF(iso)4E resistant allele. Among the 12 pvr2-eIF4E resistance alleles sequenced in the pepper gene pool, three were shown to have a complementary effect with pvr6-eIF(iso)4E for resistance. Two amino acid changes were exclusively shared by these three alleles and were systematically associated with a second amino acid change, suggesting that these substitutions are associated with resistance expression. The availability of new resistant allele combinations increases the possibility for the durable deployment of resistance against this pepper virus which is prevalent in Africa.

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Direct Interaction Between the Rice yellow mottle virus (RYMV) VPg and the Central Domain of the Rice eIF(iso)4G1 Factor Correlates with Rice Susceptibility and RYMV Virulence

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-03-10-0073 ◽

2010 ◽

Vol 23 (11) ◽

pp. 1506-1513 ◽

Cited By ~ 38

Author(s):

Eugénie Hébrard ◽

Nils Poulicard ◽

Clément Gérard ◽

Oumar Traoré ◽

Hui-Chen Wu ◽

...

Keyword(s):

Molecular Mechanisms ◽

Direct Interaction ◽

Translation Initiation Factor ◽

Initiation Factor ◽

Mottle Virus ◽

Rice Yellow Mottle Virus ◽

Recessive Resistance ◽

In Planta ◽

Central Domain ◽

Yellow Mottle

The adaptation of Rice yellow mottle virus (RYMV) to recessive resistance mediated by the rymv1-2 allele has been reported as a model to study the emergence and evolution of virulent variants. The resistance and virulence factors have been identified as eukaryotic translation initiation factor eIF(iso)4G1 and viral genome–linked protein (VPg), respectively, but the molecular mechanisms involved in their interaction are still unknown. In this study, we demonstrated a direct interaction between RYMV VPg and the central domain of rice eIF(iso)4G1 both in vitro, using recombinant proteins, and in vivo, using a yeast two-hybrid assay. Insertion of the E309K mutation in eIF(iso)4G1, conferring resistance in planta, strongly diminished the interaction with avirulent VPg. The efficiency of the major virulence mutations at restoring the interaction with the resistance protein was assessed. Our results explain the prevalence of virulence mutations fixed during experimental evolution studies and are consistent with the respective viral RNA accumulation levels of avirulent and virulent isolates. Our results also explain the origin of the residual multiplication of wild-type isolates in rymv1-2–resistant plants and the role of genetic context in the poor adaptability of the S2/S3 strain. Finally, the strategies of RYMV and members of family Potyviridae to overcome recessive resistance were compared.

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Simultaneous mutations in translation initiation factors eIF4E and eIF(iso)4E are required to prevent pepper veinal mottle virus infection of pepper

Journal of General Virology ◽

10.1099/vir.0.81817-0 ◽

2006 ◽

Vol 87 (7) ◽

pp. 2089-2098 ◽

Cited By ~ 101

Author(s):

Sandrine Ruffel ◽

Jean-Luc Gallois ◽

Benoît Moury ◽

Christophe Robaglia ◽

Alain Palloix ◽

...

Keyword(s):

Transient Expression ◽

Translation Initiation ◽

Genomic Region ◽

Translation Initiation Factor ◽

Initiation Factor ◽

Mottle Virus ◽

Susceptibility Allele ◽

Eukaryotic Translation ◽

Pepper Veinal Mottle Virus ◽

Loss Of Resistance

Capsicum resistance to Pepper veinal mottle virus (PVMV) results from complementation between the pvr2 and pvr6 resistance genes: recessive alleles at these two loci are necessary for resistance, whereas any dominant allele confers susceptibility. In line with previous results showing that pvr2 resistance alleles encode mutated versions of the eukaryotic translation initiation factor 4E (eIF4E), the involvement of other members of the eIF4E multigenic family in PVMV resistance was investigated. It was demonstrated that pvr6 corresponds to an eIF(iso)4E gene, predicted to encode the second cap-binding isoform identified in plants. Comparative genetic mapping in pepper and tomato indicated that eIF(iso)4E maps in the same genomic region as pvr6. Sequence analysis revealed an 82 nt deletion in eIF(iso)4E cDNAs from genotypes with the pvr6 resistance allele, leading to a truncated protein. This deletion was shown to co-segregate with pvr6 in doubled haploid and F2 progeny. Transient expression in a PVMV-resistant genotype of eIF(iso)4E derived from a genotype with the pvr6 + susceptibility allele resulted in loss of resistance to subsequent PVMV inoculation, confirming that pvr6 encodes the translation factor eIF(iso)4E. Similarly, transient expression of eIF4E from a genotype with the pvr2 + -eIF4E susceptibility allele also resulted in loss of resistance, demonstrating that wild-type eIF4E and eIF(iso)4E are susceptibility factors for PVMV and that resistance results from the combined effect of mutations in the two cap-binding isoforms. Thus, whilst most potyviruses specifically require one eIF4E isoform to perform their replication cycle, PVMV uses either eIF4E or eIF(iso)4E for infection of pepper.

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Hsp90 Binds and Regulates the Ligand-Inducible α Subunit of Eukaryotic Translation Initiation Factor Kinase Gcn2

Molecular and Cellular Biology ◽

10.1128/mcb.19.12.8422 ◽

1999 ◽

Vol 19 (12) ◽

pp. 8422-8432 ◽

Cited By ~ 50

Author(s):

Olivier Donzé ◽

Didier Picard

Keyword(s):

Amino Acid ◽

Constitutive Expression ◽

Amino Acid Starvation ◽

Translation Initiation Factor ◽

Initiation Factor ◽

Restrictive Temperature ◽

Α Subunit ◽

Macbecin I

ABSTRACT The protein kinase Gcn2 stimulates translation of the yeast transcription factor Gcn4 upon amino acid starvation. Using genetic and biochemical approaches, we show that Gcn2 is regulated by the molecular chaperone Hsp90 in budding yeast Saccharomyces cerevisiae. Specifically, we found that (i) several Hsp90 mutant strains exhibit constitutive expression of a GCN4-lacZ reporter plasmid; (ii) Gcn2 and Hsp90 form a complex in vitro as well as in vivo; (iii) the specific inhibitors of Hsp90, geldanamycin and macbecin I, enhance the association of Gcn2 with Hsp90 and inhibit its kinase activity in vitro; (iv) in vivo, macbecin I strongly reduces the levels of Gcn2; (v) in a strain expressing the temperature-sensitive Hsp90 mutant G170D, both the accumulation and activity of Gcn2 are abolished at the restrictive temperature; and (vi) the Hsp90 cochaperones Cdc37, Sti1, and Sba1 are required for the response to amino acid starvation. Taken together, these data identify Gcn2 as a novel target for Hsp90, which plays a crucial role for the maturation and regulation of Gcn2.

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Translation of the yeast transcriptional activator GCN4 is stimulated by purine limitation: implications for activation of the protein kinase GCN2

Molecular and Cellular Biology ◽

10.1128/mcb.13.8.5099-5111.1993 ◽

1993 ◽

Vol 13 (8) ◽

pp. 5099-5111

Author(s):

R J Rolfes ◽

A G Hinnebusch

Keyword(s):

Amino Acid ◽

Protein Kinase ◽

Transcriptional Activation ◽

Phosphorylation Site ◽

Transcriptional Activator ◽

Translation Initiation Factor ◽

Initiation Factor ◽

Single Amino Acid ◽

Biosynthetic Genes ◽

Transcriptional Activator Protein

The transcriptional activator protein GCN4 is responsible for increased transcription of more than 30 different amino acid biosynthetic genes in response to starvation for a single amino acid. This induction depends on increased expression of GCN4 at the translational level. We show that starvation for purines also stimulates GCN4 translation by the same mechanism that operates in amino acid-starved cells, being dependent on short upstream open reading frames in the GCN4 mRNA leader, the phosphorylation site in the alpha subunit of eukaryotic translation initiation factor 2 (eIF-2 alpha), the protein kinase GCN2, and translational activators of GCN4 encoded by GCN1 and GCN3. Biochemical experiments show that eIF-2 alpha is phosphorylated in response to purine starvation and that this reaction is completely dependent on GCN2. As expected, derepression of GCN4 in purine-starved cells leads to a substantial increase in HIS4 expression, one of the targets of GCN4 transcriptional activation. gcn mutants that are defective for derepression of amino acid biosynthetic enzymes also exhibit sensitivity to inhibitors of purine biosynthesis, suggesting that derepression of GCN4 is required for maximal expression of one or more purine biosynthetic genes under conditions of purine limitation. Analysis of mRNAs produced from the ADE4, ADE5,7, ADE8, and ADE1 genes indicates that GCN4 stimulates the expression of these genes under conditions of histidine starvation, and it appeared that ADE8 mRNA was also derepressed by GCN4 in purine-starved cells. Our results indicate that the general control response is more global than was previously imagined in terms of the type of nutrient starvation that elicits derepression of GCN4 as well as the range of target genes that depend on GCN4 for transcriptional activation.

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Abstract 1394: Sublethal Levels of Aldehydes Augmented Cardiac Anti-Oxidant Defense through Activation of eIF2 α -ATF4 Pathway via GCN2 Kinase

Circulation ◽

10.1161/circ.118.suppl_18.s_320 ◽

2008 ◽

Vol 118 (suppl_18) ◽

Author(s):

Takaharu Katayama ◽

Motoaki Sano ◽

Jin Endo ◽

Kentaro Hayashida ◽

Tomohiro Matsuhashi ◽

...

Keyword(s):

Amino Acid ◽

Amino Acid Metabolism ◽

Acid Metabolism ◽

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Translation Initiation Factor ◽

Initiation Factor ◽

Special Importance ◽

Dependent Manner ◽

Protein Levels

[Introduction] Despite an increase in the levels of aldehydes, the heart from aldehyde dehydrogenase ( ALDH ) 2*2 -transgenic (Tg) mice, loss of function model of ALDH, exhibited a greater tolerance to oxidative stress via activation of amino acid metabolism leading to glutathione biosynthesis. This study was designed to identify the signaling cascades responsible for the activation of amino acid metabolism by aldehydes. [Methods & Results] (1) Phosphorylation of α -subunit of eukaryotic translation initiation factor 2 (eIF2 α ) and subsequent translational activation of ATF4 have been shown to induce amino acid metabolism as a common response to a wide variety of stressors. Consistent with this, phosphorylation levels of eIF2 α and protein expression of ATF4 were increased in ALDH2*2 -Tg hearts. (2) Among four eIF2 α kinases, general control non-depressible (GCN)2 kinase, a sensor for amino acid insufficiency, was activated in ALDH2*2 -Tg heart. (3) Quantification of intracellular amino acid demonstrated that free histidine concentration in ALDH2*2 -Tg heart was selectively reduced by 50% compared to that in non-Tg littermates. (4) To clarify the functional significance of observed reduction in histidine, ALDH2*2 -Tg mice were fed a high histidine diet. The phosphorylation levels of eIF2 α and the protein levels of ATF4 were diminished by 50% in ALDH2*2 -Tg mice fed the high histidine diet, in agreement with the normalization of histidine concentration. Accordingly, both enhanced tolerance to ischemia-reperfusion injury and elevated levels of glutathione were partially diminished in the heart from ALDH2*2 -Tg mice fed the high histidine diet compared to ALDH2*2 -Tg mice fed normal chow. (5) In culture, exposure to 4-hydroxy-2-nonenal (4-HNE) phosphorylated GCN2 and eIF2 α and increased protein levels of ATF4 in a time-dependent manner. (6) siRNA-mediated knockdown of GCN2 abrogated 4-HNE-induced induction of amino acid metabolic genes. [Conclusions] Activation of eIF2 α -ATF4 pathway via GCN2 kinase might be of special importance in the transcriptional control that coordinately promotes amino acid metabolism in response to aldehydes. Intracellular depletion of free histidine is at least partly involved in the activation of GCN2 kinase by aldehydes.

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Evidence that GCD6 and GCD7, translational regulators of GCN4, are subunits of the guanine nucleotide exchange factor for eIF-2 in Saccharomyces cerevisiae.

Molecular and Cellular Biology ◽

10.1128/mcb.13.3.1920 ◽

1993 ◽

Vol 13 (3) ◽

pp. 1920-1932 ◽

Cited By ~ 52

Author(s):

J L Bushman ◽

A I Asuru ◽

R L Matts ◽

A G Hinnebusch

Keyword(s):

Saccharomyces Cerevisiae ◽

Amino Acid ◽

Translational Control ◽

Open Reading Frames ◽

Translation Initiation Factor ◽

Initiation Factor ◽

Nucleotide Exchange ◽

Yeast Saccharomyces Cerevisiae ◽

High Molecular Weight Complex ◽

Exchange Factor

Starvation of the yeast Saccharomyces cerevisiae for an amino acid signals increased translation of GCN4, a transcriptional activator of amino acid biosynthetic genes. We have isolated and characterized the GCD6 and GCD7 genes and shown that their products are required to repress GCN4 translation under nonstarvation conditions. We find that both GCD6 and GCD7 show sequence similarities to components of a high-molecular-weight complex (the GCD complex) that appears to be the yeast equivalent of translation initiation factor 2B (eIF-2B), which catalyzes GDP-GTP exchange on eIF-2. Furthermore, we show that GCD6 is 30% identical to the largest subunit of eIF-2B isolated from rabbit reticulocytes. Deletion of either GCD6 or GCD7 is lethal, and nonlethal mutations in these genes increase GCN4 translation in the same fashion described for defects in known subunits of eIF-2 or the GCD complex; derepression of GCN4 is dependent on short open reading frames in the GCN4 mRNA leader and occurs independently of eIF-2 alpha phosphorylation by protein kinase GCN2, which is normally required to stimulate GCN4 translation. Together, our results provide evidence that GCD6 and GCD7 are subunits of eIF-2B in S. cerevisiae and further implicate this GDP-GTP exchange factor in gene-specific translational control.

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Recessive Resistance to Bean common mosaic virus Conferred by the bc-1 and bc-2 Genes in Common Bean (Phaseolus vulgaris) Affects Long-Distance Movement of the Virus

Phytopathology ◽

10.1094/phyto-01-18-0021-r ◽

2018 ◽

Vol 108 (8) ◽

pp. 1011-1018 ◽

Cited By ~ 4

Author(s):

Xue Feng ◽

Gardenia E. Orellana ◽

James R. Myers ◽

Alexander V. Karasev

Keyword(s):

Phaseolus Vulgaris ◽

Common Bean ◽

Mosaic Virus ◽

Bean Common Mosaic Virus ◽

Translation Initiation Factor ◽

Initiation Factor ◽

Recessive Resistance ◽

Long Distance ◽

Systemic Spread ◽

Long Distance Movement

Recessive resistance to Bean common mosaic virus (BCMV) in common bean (Phaseolus vulgaris) is governed by four genes that include one strain-nonspecific helper gene bc-u, and three strain-specific genes bc-1, bc-2, and bc-3. The bc-3 gene was identified as an eIF4E translation initiation factor gene mediating resistance through disruption of the interaction between this protein and the VPg protein of the virus. The mode of action of bc-1 and bc-2 in expression of BCMV resistance is unknown, although bc-1 gene was found to affect systemic spread of a related potyvirus, Bean common mosaic necrosis virus. To investigate the possible role of both bc-1 and bc-2 genes in replication, cell-to-cell, and long-distance movement of BCMV in P. vulgaris, we tested virus spread of eight BCMV isolates representing pathogroups I, IV, VI, VII, and VIII in a set of bean differentials expressing different combinations of six resistance alleles including bc-u, bc-1, bc-12, bc-2, bc-22, and bc-3. All studied BCMV isolates were able to replicate and spread in inoculated leaves of bean cultivars harboring bc-u, bc-1, bc-12, bc-2, and bc-22 alleles and their combinations, while no BCMV replication was found in inoculated leaves of cultivar IVT7214 carrying the bc-u, bc-2, and bc-3 genes, except for isolate 1755a, which was capable of overcoming the resistance conferred by bc-2 and bc-3. In contrast, the systemic spread of all BCMV isolates from pathogroups I, IV, VI, VII, and VIII was impaired in common bean cultivars carrying bc-1, bc-12, bc-2, and bc-22 alleles. The data suggest that bc-1 and bc-2 recessive resistance genes have no effect on the replication and cell-to-cell movement of BCMV, but affect systemic spread of BCMV in common bean. The BCMV resistance conferred by bc-1 and bc-2 and affecting systemic spread was found only partially effective when these two genes were expressed singly. The efficiency of the restriction of the systemic spread of the virus was greatly enhanced when the alleles of bc-1 and bc-2 genes were combined together.

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Mutations in the eIF(iso)4G translation initiation factor confer high resistance of rice toRice yellow mottle virus

The Plant Journal ◽

10.1111/j.1365-313x.2006.02792.x ◽

2006 ◽

Vol 47 (3) ◽

pp. 417-426 ◽

Cited By ~ 128

Author(s):

Laurence Albar ◽

Martine Bangratz-Reyser ◽

Eugénie Hébrard ◽

Marie-Noëlle Ndjiondjop ◽

Monty Jones ◽

...

Keyword(s):

Translation Initiation ◽

High Resistance ◽

Translation Initiation Factor ◽

Initiation Factor ◽

Mottle Virus ◽

Yellow Mottle

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Physiological rise in plasma leucine stimulates muscle protein synthesis in neonatal pigs by enhancing translation initiation factor activation

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00510.2004 ◽

2005 ◽

Vol 288 (5) ◽

pp. E914-E921 ◽

Cited By ~ 93

Author(s):

Jeffery Escobar ◽

Jason W. Frank ◽

Agus Suryawan ◽

Hanh V. Nguyen ◽

Scot R. Kimball ◽

...

Keyword(s):

Skeletal Muscle ◽

Protein Synthesis ◽

Amino Acid ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Mrna Translation ◽

Translation Initiation Factor ◽

Initiation Factor ◽

Neonatal Pigs ◽

Plasma Leucine

Protein synthesis in skeletal muscle of adult rats increases in response to oral gavage of supraphysiological doses of leucine. However, the effect on protein synthesis of a physiological rise in plasma leucine has not been investigated in neonates, an anabolic population highly sensitive to amino acids and insulin. Therefore, in the current study, fasted pigs were infused intra-arterially with leucine (0, 200, or 400 μmol·kg−1·h−1), and protein synthesis was measured after 60 or 120 min. Protein synthesis was increased in muscle, but not in liver, at 60 min. At 120 min, however, protein synthesis returned to baseline levels in muscle but was reduced below baseline values in liver. The increase in protein synthesis in muscle was associated with increased plasma leucine of 1.5- to 3-fold and no change in plasma insulin. Leucine infusion for 120 min reduced plasma essential amino acid levels. Phosphorylation of eukaryotic initiation factor (eIF)-4E-binding protein-1 (4E-BP1), ribosomal protein (rp) S6 kinase, and rpS6 was increased, and the amount of eIF4E associated with its repressor 4E-BP1 was reduced after 60 and 120 min of leucine infusion. No change in these biomarkers of mRNA translation was observed in liver. Thus a physiological increase in plasma leucine stimulates protein synthesis in skeletal muscle of neonatal pigs in association with increased eIF4E availability for eIF4F assembly. This response appears to be insulin independent, substrate dependent, and tissue specific. The results suggest that the branched-chain amino acid leucine can act as a nutrient signal to stimulate protein synthesis in skeletal muscle of neonates.

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A Novel Function of the MA-3 Domains in Transformation and Translation Suppressor Pdcd4 Is Essential for Its Binding to Eukaryotic Translation Initiation Factor 4A

Molecular and Cellular Biology ◽

10.1128/mcb.24.9.3894-3906.2004 ◽

2004 ◽

Vol 24 (9) ◽

pp. 3894-3906 ◽

Cited By ~ 141

Author(s):

Hsin-Sheng Yang ◽

Myung-Haing Cho ◽

Halina Zakowicz ◽

Glenn Hegamyer ◽

Nahum Sonenberg ◽

...

Keyword(s):

Amino Acid ◽

Translation Initiation ◽

Binding Activity ◽

Translation Initiation Factor ◽

Initiation Factor ◽

Amino Acid Residues ◽

Eukaryotic Translation Initiation Factor ◽

Stem Loop ◽

Eukaryotic Translation ◽

Eukaryotic Translation Initiation

ABSTRACT Αn α-helical MA-3 domain appears in several translation initiation factors, including human eukaryotic translation initiation factor 4G (eIF4G) and DAP-5/NAT1/p97, as well as in the tumor suppressor Pdcd4. The function of the MA-3 domain is, however, unknown. C-terminal eIF4G (eIG4Gc) contains an MA-3 domain that is located within the eIF4A-binding region, suggesting a role for eIF4A binding. Interestingly, C-terminal DAP-5/NAT1/p97 contains an MA-3 domain, but it does not bind to eIF4A. Mutation of amino acid residues conserved between Pdcd4 and eIF4Gc but not in DAP-5/NAT1/p97 to the amino acid residues found in the DAP-5/NAT1/p97 indicates that some of these amino acid residues within the MA-3 domain are critical for eIF4A-binding activity. Six Pdcd4 mutants (Pdcd4E249K, Pdcd4D253A, Pdcd4D414K, Pdcd4D418A, Pdcd4E249K,D414K, and Pdcd4D253A,D418A) lost >90% eIF4A-binding activity. Mutation of the corresponding amino acid residues in the eIF4Gc also produced similar results, as seen for Pdcd4. These results demonstrate that the MA-3 domain is important for eIF4A binding and explain the ability of Pdcd4 or eIF4Gc but not DAP-5/NAT1/p97 to bind to eIF4A. Competition experiments indicate that Pdcd4 prevents ca. 60 to 70% of eIF4A binding to eIF4Gc at a Pdcd4/eIF4A ratio of 1:1, but mutants Pdcd4D253A and Pdcd4D253A,D418A do not. Translation of stem-loop structured mRNA is susceptible to inhibition by wild-type Pdcd4 but not by Pdcd4D253A, Pdcd4D418A, or Pdcd4D235A,D418A. Together, these results indicate that not only binding to eIF4A but also prevention of eIF4A binding to the MA-3 domain of eIF4Gc contributes to the mechanism by which Pdcd4 inhibits translation.

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