Polycistronic mRNAs and internal ribosome entry site elements (IRES) are widely used by white spot syndrome virus (WSSV) structural protein genes.
The genome of the white spot syndrome virus (WSSV) Taiwan isolate has many structural and non-structural genes that are arranged in clusters. Screening with Northern blots showed that at least four of these clusters produce polycistronic mRNA, and one of these (vp31/vp39b/vp11) was studied in detail. The vp31/vp39b/vp11 cluster produces two transcripts, including a large 3.4-kb polycistronic transcript of all three genes. No monocistronic vp39b mRNA was detected. TNT and in vitro translation assays showed that vp39b translation was independent of vp31 translation, and that ribosomal reinitiation was not a possible mechanism for vp39b. An unusually located IRES (internal ribosome entry site) element was identified in the vp31/vp39b coding region, and this region was able to promote the expression of a downstream firefly luciferase reporter. We show that vp31/vp39b/vp11 is representative of many other WSSV structural/non-structural gene clusters, and argue that these are also likely to produce polycistronic mRNAs and that use an IRES mechanism to regulate their translation.
Kang
Shih-Ting
ST
Institute of Zoology, National Taiwan University, Taipei, Taiwan.
Leu
Jiann-Horng
JH
Wang
Han-Ching
HC
Chen
Li-Li
LL
Kou
Guang-Hsiung
GH
Lo
Chu-Fang
CF
D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D008969:Molecular Sequence Data; D005810:Multigene Family; D033561:Penaeidae / Q000378:metabolism / Q000821:virology; D014176:Protein Biosynthesis; D012314:RNA Cap Analogs; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics*; D012367:RNA, Viral / Q000032:analysis / Q000235:genetics; D012270:Ribosomes / Q000378:metabolism*; D014764:Viral Proteins / Q000096:biosynthesis / Q000235:genetics*; D046848:White spot syndrome virus 1 / Q000235:genetics* / Q000378:metabolism
D012314:RNA Cap Analogs; D012333:RNA, Messenger; D012367:RNA, Viral; D014764:Viral Proteins