title: Alternative Polyadenylation of Human Bocavirus at Its 3' End Is Regulated by Multiple Elements and Affects Capsid Expression.
abstract: Alternative processing of human bocavirus (HBoV) P5 promoter-transcribed RNA is critical for generating the structural and nonstructural protein-encoding mRNA transcripts. The regulatory mechanism by which HBoV RNA transcripts are polyadenylated at proximal [(pA)p] or distal [(pA)d] polyadenylation sites is still unclear. We constructed a recombinant HBoV infectious clone to study the alternative polyadenylation regulation of HBoV. Surprisingly, in addition to the reported distal polyadenylation site, (pA)d, a novel distal polyadenylation site, (pA)d2, which is located in the right-end hairpin (REH), was identified during infectious clone transfection or recombinant virus infection. (pA)d2 does not contain typical hexanucleotide polyadenylation signal, upstream elements (USE), or downstream elements (DSE) according to sequence analysis. Further study showed that HBoV nonstructural protein NS1, REH, and cis elements of (pA)d were necessary and sufficient for efficient polyadenylation at (pA)d2. The distance and sequences between (pA)d and (pA)d2 also played a key role in the regulation of polyadenylation at (pA)d2. Finally, we demonstrated that efficient polyadenylation at (pA)d2 resulted in increased HBoV capsid mRNA transcripts and protein translation. Thus, our study revealed that all the bocaviruses have distal poly(A) signals on the right-end palindromic terminus, and alternative polyadenylation at the HBoV 3' end regulates its capsid expression.
  
  
  OBJECTIVE
  The distal polyadenylation site, (pA)d, of HBoV is located about 400 nucleotides (nt) from the right-end palindromic terminus, which is different from those of bovine parvovirus (BPV) and canine minute virus (MVC) in the same genus whose distal polyadenylation is located in the right-end stem-loop structure. A novel polyadenylation site, (pA)d2, was identified in the right-end hairpin of HBoV during infectious clone transfection or recombinant virus infection. Sequence analysis showed that (pA)d2 does not contain typical polyadenylation signals, and the last 42 nt form a stem-loop structure which is almost identical to that of MVC. Further study showed that NS1, REH, and cis elements of (pA)d are required for efficient polyadenylation at (pA)d2. Polyadenylation at (pA)d2 enhances capsid expression. Our study demonstrates alternative polyadenylation at the 3' end of HBoV and suggests an additional mechanism by which capsid expression is regulated.
authors.affiliation: Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, China.|University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Sujuan
authors.initials: S
authors.lastname: Hao
authors.affiliation: Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, China.|University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Junmei
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, China.|University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Huanzhou
authors.initials: H
authors.lastname: Xu
authors.affiliation: Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, China.
authors.forename: Hanzhong
authors.initials: H
authors.lastname: Wang
authors.affiliation: Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, China guanwx@wh.iov.cn.|Hubei Collaborative Innovation Center for Industrial Fermentation, Wuhan, Hubei, China.
authors.forename: Wuxiang
authors.identifier: http://orcid.org/0000-0002-2415-4659
authors.initials: W
authors.lastname: Guan
mesh_terms: D017398:Alternative Splicing; D001483:Base Sequence; D036022:Capsid Proteins / Q000235:genetics*; D002460:Cell Line; D015967:Gene Expression Regulation, Viral; D056661:Human bocavirus / Q000502:physiology*; D006801:Humans; D009154:Mutation; D011061:Poly A; D026723:Polyadenylation; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D020079:Terminal Repeat Sequences; D014158:Transcription, Genetic
chemical_list: D036022:Capsid Proteins; D012333:RNA, Messenger; D011061:Poly A
keywords: HBoV; alternative polyadenylation; capsid protein expression; parvovirus