title: The Autographa californica Multiple Nucleopolyhedrovirusac83Gene Contains acis-Acting Element That Is Essential for Nucleocapsid Assembly.
abstract: Baculoviridaeis a family of insect-specific viruses that have a circular double-stranded DNA genome packaged within a rod-shaped capsid. The mechanism of baculovirus nucleocapsid assembly remains unclear. Previous studies have shown that deletion of theac83gene of Autographa californica multiple nucleopolyhedrovirus (AcMNPV) blocks viral nucleocapsid assembly. Interestingly, theac83-encoded protein Ac83 is not a component of the nucleocapsid, implying a particular role forac83in nucleocapsid assembly that may be independent of its protein product. To examine this possibility, Ac83 synthesis was disrupted by insertion of a chloramphenicol resistance gene into its coding sequence or by deleting its promoter and translation start codon. Both mutants produced progeny viruses normally, indicating that the Ac83 protein is not required for nucleocapsid assembly. Subsequently, complementation assays showed that the production of progeny viruses required the presence ofac83in the AcMNPV genome instead of its presence intransTherefore, we reasoned thatac83is involved in nucleocapsid assembly via an internalcis-acting element, which we named the nucleocapsid assembly-essential element (NAE). The NAE was identified to lie within nucleotides 1651 to 1850 ofac83and had 8 conserved A/T-rich regions. Sequences homologous to the NAE were found only in alphabaculoviruses and have a conserved positional relationship with another essentialcis-acting element that was recently identified. The identification of the NAE may help to connect the data of viralcis-acting elements and related proteins in the baculovirus nucleocapsid assembly, which is important for elucidating DNA-protein interaction events during this process.IMPORTANCEVirus nucleocapsid assembly usually requires specificcis-acting elements in the viral genome for various processes, such as the selection of the viral genome from the cellular nucleic acids, the cleavage of concatemeric viral genome replication intermediates, and the encapsidation of the viral genome into procapsids. In linear DNA viruses, such elements generally locate at the ends of the viral genome; however, most of these elements remain unidentified in circular DNA viruses (including baculovirus) due to their circular genomic conformation. Here, we identified a nucleocapsid assembly-essential element in the AcMNPV (the archetype of baculovirus) genome. This finding provides an important reference for studies of nucleocapsid assembly-related elements in baculoviruses and other circular DNA viruses. Moreover, as most of the previous studies of baculovirus nucleocapsid assembly have been focused on viral proteins, our study provides a novel entry point to investigate this mechanism viacis-acting elements in the viral genome.
authors.affiliation: State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou, China.
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou, China.
authors.forename: Mengjia
authors.initials: M
authors.lastname: Pan
authors.affiliation: State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou, China.
authors.forename: Silei
authors.initials: S
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou, China.
authors.forename: Wenbi
authors.initials: W
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou, China.
authors.forename: Meijin
authors.initials: M
authors.lastname: Yuan
authors.affiliation: State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou, China yangkai@mail.sysu.edu.cn.
authors.forename: Kai
authors.initials: K
authors.lastname: Yang
mesh_terms: D000818:Animals; D001483:Base Sequence; D036022:Capsid Proteins / Q000235:genetics*; D017124:Conserved Sequence; D019251:Nucleocapsid / Q000235:genetics / Q000378:metabolism*; D017924:Nucleopolyhedroviruses / Q000502:physiology*; D054730:Protein Interaction Domains and Motifs; D055503:Protein Multimerization; D017422:Sequence Analysis, DNA; D061987:Sf9 Cells; D018411:Spodoptera; D019065:Virus Assembly; D014779:Virus Replication
chemical_list: D036022:Capsid Proteins
keywords: ac83; baculovirus; cis-acting element; dsDNA virus; nucleocapsid assembly