A plant viral "reinitiation" factor interacts with the host translational machinery.
The cauliflower mosaic virus transactivator, TAV, controls translation reinitiation of major open reading frames on polycistronic RNA. We show here that TAV function depends on its association with polysomes and eukaryotic initiation factor eIF3 in vitro and in vivo. TAV physically interacts with eIF3 and the 60S ribosomal subunit. Two proteins mediating these interactions were identified: eIF3g and 60S ribosomal protein L24. Transient expression of eIF3g and L24 in plant protoplasts strongly affects TAV-mediated reinitiation activity. We demonstrate that TAV/eIF3/40S and eIF3/TAV/60S ternary complexes form in vitro, and propose that TAV mediates efficient recruitment of eIF3 to polysomes, allowing translation of polycistronic mRNAs by reinitiation, overcoming the normal cell barriers to this process.
Park
H S
HS
Friedrich Miescher-Institute, P.O. Box 2543, CH-4002, Basel, Switzerland.
Himmelbach
A
A
Browning
K S
KS
Hohn
T
T
Ryabova
L A
LA
D000595:Amino Acid Sequence; D001937:Brassica / Q000235:genetics* / Q000821:virology*; D017796:Caulimovirus / Q000235:genetics* / Q000502:physiology; D003001:Cloning, Molecular; D017124:Conserved Sequence; D039621:Eukaryotic Initiation Factor-3; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010448:Peptide Initiation Factors / Q000378:metabolism; D011132:Polyribosomes / Q000378:metabolism; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics; D012269:Ribosomal Proteins / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic; D014908:Triticum / Q000235:genetics
D039621:Eukaryotic Initiation Factor-3; D010448:Peptide Initiation Factors; D012333:RNA, Messenger; D012269:Ribosomal Proteins; D015534:Trans-Activators; C036298:ribosomal protein L24