Translational control of the subgenomic RNAs of severe acute respiratory syndrome coronavirus.
The 3'-one-third of the severe acute respiratory syndrome coronavirus (SARS-CoV) genome contains genes for four essential structural proteins and eight virus-specific genes. The expression of this genomic information of SARS-CoV involves synthesis of a nested set of subgenomic RNAs (sgRNAs). In this study, we showed that the translational levels of 10 SARS-CoV sgRNAs including the two low-abundance sgRNAs 2-1 and 3-1 varied considerably in translation reporter assays. We also demonstrated that the initiator AUG codon of sgRNA-8 was silent and the repressive control was most likely positioned in the upstream untranslated region (UTR) of sgRNA-8. The initiator AUG codons of most sgRNAs are in poor Kozak contexts and the translation of truncated proteins from downstream AUG codons by leaky scanning was common in our experimental settings. No significant correlation was found between complexity of 5'-UTR and the sequence context of AUG codon with the level of translation of SARS-CoV sgRNAs. These results will be helpful for further studies to reveal the biological functions and translation regulatory mechanisms of sgRNAs in the coronavirus life cycle and pathogenesis.
State Key Laboratory of Virology and the Modern Virology Research Centre, College of Life Sciences, Wuhan University, Wuhan 430072, People's Republic of China.
Yaling
Y
Yang
Snawar
S
Hussain
Hao
H
Wang
Min
M
Ke
Deyin
D
Guo
D020121:5' Untranslated Regions; D000818:Animals; D002460:Cell Line; D018387:Codon, Initiator; D006224:Cricetinae; D015967:Gene Expression Regulation, Viral; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D014176:Protein Biosynthesis; D012367:RNA, Viral / Q000378:metabolism*; D045473:Severe acute respiratory syndrome-related coronavirus / Q000502:physiology*
D020121:5' Untranslated Regions; D018387:Codon, Initiator; D012367:RNA, Viral; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D008156:Luciferases