Ring structure amino acids affect the suppressor activity of melon aphid-borne yellows virus P0 protein.
Melon aphid-borne yellows virus (MABYV) is a newly identified polerovirus occurring in China. Here, we demonstrate that the MABYV encoded P0 (P0(MA)) protein is a strong suppressor of post-transcriptional gene silencing (PTGS) with activity comparable to tobacco etch virus (TEV) HC-Pro. In addition we have shown that the LP F-box motif present at the N-terminus of P0(MA) is required for suppressor activity. Detailed mutational analyses on P0(MA) revealed that changing the conserved Trp 212 with non-ring structured amino acids altered silencing suppressor functions. Ala substitutions at positions 12 and 211 for Phe had no effect on P0 suppression-activity, whereas Arg and Glu substitutions had greatly decreased suppressor activity. Furthermore, substitutions targeting Phe at position 30 also resulted in reduced P0 suppression-activity. Altogether, these results suggest that ring structured Trp/Phe residues in P0 have important roles in suppressor activity.
Han
Yan-Hong
YH
State Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing, P. R. China. han.037@163.com
Xiang
Hai-Ying
HY
Wang
Qian
Q
Li
Yuan-Yuan
YY
Wu
Wen-Qi
WQ
Han
Cheng-Gui
CG
Li
Da-Wei
DW
Yu
Jia-Lin
JL
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000596:Amino Acids / Q000737:chemistry; D000818:Animals; D001042:Aphids / Q000821:virology; D001483:Base Sequence; D002681:China; D019662:Cucurbitaceae / Q000821:virology; D017931:DNA Primers / Q000235:genetics; D004279:DNA, Viral / Q000235:genetics; D005814:Genes, Viral; D049452:Green Fluorescent Proteins / Q000235:genetics; D007303:Insect Vectors / Q000821:virology; D052679:Luteoviridae / Q000235:genetics* / Q000472:pathogenicity / Q000502:physiology*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D030821:Plants, Genetically Modified; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D014026:Nicotiana / Q000235:genetics / Q000821:virology; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*
D000596:Amino Acids; D017931:DNA Primers; D004279:DNA, Viral; D050505:Mutant Proteins; D034741:RNA, Small Interfering; D014764:Viral Proteins; D049452:Green Fluorescent Proteins