The Arabidopsis cucumovirus multiplication 1 and 2 loci encode translation initiation factors 4E and 4G.
The cum1 and cum2 mutations of Arabidopsis thaliana inhibit cucumber mosaic virus (CMV) multiplication. In cum1 and cum2 protoplasts, CMV RNA and the coat protein accumulated to wild-type levels, but the accumulation of the 3a protein of CMV, which is necessary for cell-to-cell movement of the virus, was strongly reduced compared with that in wild-type protoplasts. In cum2 protoplasts, the accumulation of turnip crinkle virus (TCV)-related RNA and proteins was also reduced. Positional cloning demonstrated that CUM1 and CUM2 encode eukaryotic translation initiation factors 4E and 4G, respectively. Unlike most cellular mRNA, the CMV RNA lacks a poly(A) tail, whereas the TCV RNA lacks both a 5'-terminal cap and a poly(A) tail. In vivo translation analyses, using chimeric luciferase mRNA carrying the terminal structures and untranslated sequences of the CMV or TCV RNA, demonstrated that these viral untranslated sequences contain elements that regulate the expression of encoded proteins positively or negatively. The cum1 and cum2 mutations had different effects on the action of these elements, suggesting that the cum1 and cum2 mutations cause inefficient production of CMV 3a protein and that the cum2 mutation affects the production of TCV-encoded proteins.
Yoshii
Motoyasu
M
Plant Physiology Department, National Institute of Agrobiological Sciences, Tsukuba 305-8602, Japan. ishika32@affrc.go.jp
Nishikiori
Masaki
M
Tomita
Kayo
K
Yoshioka
Norimichi
N
Kozuka
Reiko
R
Naito
Satoshi
S
Ishikawa
Masayuki
M
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000821:virology*; D001483:Base Sequence; D019184:Carmovirus / Q000235:genetics / Q000378:metabolism; D002874:Chromosome Mapping; D017799:Cucumovirus / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology; D039561:Eukaryotic Initiation Factor-4E / Q000235:genetics / Q000378:metabolism*; D039603:Eukaryotic Initiation Factor-4G / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D053830:Plant Viral Movement Proteins; D011523:Protoplasts / Q000821:virology; D012367:RNA, Viral / Q000096:biosynthesis / Q000235:genetics; D017422:Sequence Analysis, DNA; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism
D039561:Eukaryotic Initiation Factor-4E; D039603:Eukaryotic Initiation Factor-4G; D053830:Plant Viral Movement Proteins; D012367:RNA, Viral; D014764:Viral Proteins