title: Host Cellular Protein TRAPPC6AΔ Interacts with Influenza A Virus M2 Protein and Regulates Viral Propagation by Modulating M2 Trafficking.
abstract: Influenza A virus (IAV) matrix protein 2 (M2) plays multiple roles in the early and late phases of viral infection. Once synthesized, M2 is translocated to the endoplasmic reticulum (ER), travels to the Golgi apparatus, and is sorted at the trans-Golgi network (TGN) for transport to the apical plasma membrane, where it functions in virus budding. We hypothesized that M2 trafficking along with its secretory pathway must be finely regulated, and host factors could be involved in this process. However, no studies examining the role of host factors in M2 posttranslational transport have been reported. Here, we used a yeast two-hybrid (Y2H) system to screen for host proteins that interact with the M2 protein and identified transport protein particle complex 6A (TRAPPC6A) as a potential binding partner. We found that both TRAPPC6A and its N-terminal internal-deletion isoform, TRAPPC6A delta (TRAPPC6AΔ), interact with M2. Truncation and mutation analyses showed that the highly conserved leucine residue at position 96 of M2 is critical for mediating this interaction. The role of TRAPPC6AΔ in the viral life cycle was investigated by the knockdown of endogenous TRAPPC6AΔ with small interfering RNA (siRNA) and by generating a recombinant virus that was unable to interact with TRAPPC6A/TRAPPC6AΔ. The results indicated that TRAPPC6AΔ, through its interaction with M2, slows M2 trafficking to the apical plasma membrane, favors viral replication in vitro, and positively modulates virus virulence in mice.
  
  
  OBJECTIVE
  The influenza A virus M2 protein regulates the trafficking of not only other proteins but also itself along the secretory pathway. However, the host factors involved in the regulation of the posttranslational transport of M2 are largely unknown. In this study, we identified TRAPPC6A and its N-terminal internal-deletion isoform, TRAPPC6AΔ, as interacting partners of M2. We found that the leucine (L) residue at position 96 of M2 is critical for mediating this interaction, which leads us to propose that the high level of conservation of 96L is a consequence of M2 adaptation to its interacting host factor TRAPPC6A/TRAPPC6AΔ. Importantly, we discovered that TRAPPC6AΔ can positively regulate viral replication in vitro by modulating M2 trafficking to the plasma membrane.
authors: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
authors: Pengyang
authors: P
authors: Zhu
authors: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
authors: Libin
authors: L
authors: Liang
authors: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
authors: Xinyuan
authors: X
authors: Shao
authors: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
authors: Weiyu
authors: W
authors: Luo
authors: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
authors: Shuitao
authors: S
authors: Jiang
authors: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
authors: Qingqing
authors: Q
authors: Zhao
authors: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
authors: Nan
authors: N
authors: Sun
authors: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
authors: Yuhui
authors: Y
authors: Zhao
authors: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
authors: Junping
authors: J
authors: Li
authors: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
authors: Jinguang
authors: J
authors: Wang
authors: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
authors: Yuan
authors: Y
authors: Zhou
authors: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
authors: Jie
authors: J
authors: Zhang
authors: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
authors: Guangwen
authors: G
authors: Wang
authors: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
authors: Li
authors: L
authors: Jiang
authors: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China chenhualan@caas.cn lichengjun@caas.cn.
authors: Hualan
authors: H
authors: Chen
authors: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China chenhualan@caas.cn lichengjun@caas.cn.
authors: Chengjun
authors: C
authors: Li
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000276:immunology / Q000821:virology; D004285:Dogs; D004847:Epithelial Cells / Q000821:virology; D005260:Female; D015870:Gene Expression; D057809:HEK293 Cells; D054884:Host-Pathogen Interactions; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000737:chemistry / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity; D053124:Influenza A Virus, H5N1 Subtype / Q000737:chemistry / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity; D061985:Madin Darby Canine Kidney Cells; D051379:Mice; D008807:Mice, Inbred BALB C; D009457:Neuroglia / Q000821:virology; D009976:Orthomyxoviridae Infections / Q000235:genetics / Q000276:immunology / Q000401:mortality / Q000821:virology*; D011485:Protein Binding; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D016019:Survival Analysis; D020798:Two-Hybrid System Techniques; D033921:Vesicular Transport Proteins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D014763:Viral Matrix Proteins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D057074:Virus Release / Q000235:genetics / Q000276:immunology; D014779:Virus Replication / Q000235:genetics / Q000276:immunology; D021601:trans-Golgi Network / Q000821:virology; D000086082:Viroporin Proteins
chemical_list: D011993:Recombinant Fusion Proteins; D033921:Vesicular Transport Proteins; D014763:Viral Matrix Proteins; C488937:M2 protein, Influenza A virus; D000086082:Viroporin Proteins
keywords: M2; TRAPPC6AΔ; influenza A virus; transport