Oligomerization of Baculovirus LEF-11 Is Involved in Viral DNA Replication.

Hai-Qing Li,Nan Hu,Peng Chen,Ming-Ya Cao,Miguel Lopez-Ferber,Zhan-Qi Dong,Min-Hui Pan,Cheng Lu,Jun Zhang,Ting-Ting Chen,Xue-Jiao Lei

doi:10.1371/journal.pone.0144930

Abstract

We have previously reported that baculovirus Bombyx mori nucleopolyhedrovirus (BmNPV) late expression factor 11 (lef-11) is associated with viral DNA replication and have demonstrated that it potentially interacts with itself; however, whether LEF-11 forms oligomers and the impact of LEF-11 oligomerization on viral function have not been substantiated. In this study, we first demonstrated that LEF-11 is capable of forming oligomers. Additionally, a series of analyses using BmNPV LEF-11 truncation mutants indicated that two distinct domains control LEF-11 oligomerization (aa 42–61 and aa 72–101). LEF-11 truncation constructs were inserted into a lef-11-knockout BmNPV bacmid, which was used to demonstrate that truncated LEF-11 lacking either oligomerization domain abrogates viral DNA replication. Finally, site-directed mutagenesis was used to determine that the conserved hydrophobic residues Y58&I59 (representing Y58 and I59), I85 and L88&L89 (representing L88 and L89) are required for LEF-11 oligomerization and viral DNA replication. Collectively, these data indicate that BmNPV LEF-11 oligomerization influences viral DNA replication.

Highlights

Baculoviruses are a highly diverse group of viruses with large, circular, double-stranded DNA genomes that exclusively infect invertebrates [1,2]
We found that residues Y58&I59, I85 and L88&L89 are required for LEF-11 oligomerization and viral DNA replication
Further analysis by Co-Immunoprecipitation Assays (Co-IP) verified that LEF-11 interacts with itself, as the LEF-11:cMYC fusion protein co-precipitated with the LEF-11:FLAG fusion protein in co-transfected BmN-SWU1 cells (Fig 1B)

Summary

Introduction

Baculoviruses are a highly diverse group of viruses with large, circular, double-stranded DNA genomes that exclusively infect invertebrates [1,2]. Specific genes have been identified that are required for viral DNA replication, and major advances have been made in understanding the functions of most of these genes in Alphabaculovirus; the functional roles of DNA replication factors have not been fully elucidated [3,4,5,6,7,8]. Previous research has identified at least 10 such factors (lef-1, lef-2, lef-3, lef-7, lef-11, ie-1, ie, p143, dnapol and p35) [3,5,6,7,9,10]. Late expression factor 11 (lef-11) of Autographa californica multiple nucleopolyhedrovirus (AcMNPV) encodes a protein with a predicted molecular weight of approximately 13.1 kDa that is required for viral DNA replication and late/very late gene activation[11,12].

Methods

Results

Conclusion