Mutational analysis of plant cap-binding protein eIF4E reveals key amino acids involved in biochemical functions and potyvirus infection.
The eukaryotic translation initiation factor 4E (eIF4E) (the cap-binding protein) is involved in natural resistance against several potyviruses in plants. In lettuce, the recessive resistance genes mo1(1) and mo1(2) against Lettuce mosaic virus (LMV) are alleles coding for forms of eIF4E unable, or less effective, to support virus accumulation. A recombinant LMV expressing the eIF4E of a susceptible lettuce variety from its genome was able to produce symptoms in mo1(1) or mo1(2) varieties. In order to identify the eIF4E amino acid residues necessary for viral infection, we constructed recombinant LMV expressing eIF4E with point mutations affecting various amino acids and compared the abilities of these eIF4E mutants to complement LMV infection in resistant plants. Three types of mutations were produced in order to affect different biochemical functions of eIF4E: cap binding, eIF4G binding, and putative interaction with other virus or host proteins. Several mutations severely reduced the ability of eIF4E to complement LMV accumulation in a resistant host and impeded essential eIF4E functions in yeast. However, the ability of eIF4E to bind a cap analogue or to fully interact with eIF4G appeared unlinked to LMV infection. In addition to providing a functional mutational map of a plant eIF4E, this suggests that the role of eIF4E in the LMV cycle might be distinct from its physiological function in cellular mRNA translation.
German-Retana
Sylvie
S
Interactions Plante-Virus, UMR GDPP 1090, INRA Université de Bordeaux 2, BP 81, F-33883 Villenave d'Ornon Cedex, France. german@bordeaux.inra.fr
Walter
Jocelyne
J
Doublet
Bénédicte
B
Roudet-Tavert
Geneviève
G
Nicaise
Valérie
V
Lecampion
Cécile
C
Houvenaghel
Marie-Christine
MC
Robaglia
Christophe
C
Michon
Thierry
T
Le Gall
Olivier
O
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D004252:DNA Mutational Analysis; D039561:Eukaryotic Initiation Factor-4E / Q000235:genetics / Q000378:metabolism*; D039603:Eukaryotic Initiation Factor-4G / Q000378:metabolism; D005816:Genetic Complementation Test; D007113:Immunity, Innate; D018545:Lactuca / Q000502:physiology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D020125:Mutation, Missense; D010935:Plant Diseases / Q000276:immunology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D017354:Point Mutation; D017800:Potyvirus / Q000276:immunology*; D011485:Protein Binding; D011487:Protein Conformation; D012315:RNA Caps / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D016415:Sequence Alignment
D039561:Eukaryotic Initiation Factor-4E; D039603:Eukaryotic Initiation Factor-4G; D010940:Plant Proteins; D012315:RNA Caps