title: BKV agnoprotein interacts with α-soluble N-ethylmaleimide-sensitive fusion attachment protein, and negatively influences transport of VSVG-EGFP.
abstract: BACKGROUND
  The human polyomavirus BK (BKV) infects humans worldwide and establishes a persistent infection in the kidney. The BK virus genome encodes three regulatory proteins, large and small tumor-antigen and the agnoprotein, as well as the capsid proteins VP1 to VP3. Agnoprotein is conserved among BKV, JC virus (JCV) and SV40, and agnoprotein-deficient mutants reveal reduced viral propagation. Studies with JCV and SV40 indicate that their agnoproteins may be involved in transcription, replication and/or nuclear and cellular release of the virus. However, the exact function(s) of agnoprotein of BK virus remains elusive.
  
  
  RESULTS
  As a strategy of exploring the functions of BKV agnoprotein, we decided to look for cellular interaction partners for the viral protein. Several partners were identified by yeast two-hybrid assay, among them α-SNAP which is involved in disassembly of vesicles during secretion. BKV agnoprotein and α-SNAP were found to partially co-localize in cells, and a complex consisting of agnoprotein and α-SNAP could be co-immunoprecipitated from cells ectopically expressing the proteins as well as from BKV-transfected cells. The N-terminal part of the agnoprotein was sufficient for the interaction with α-SNAP. Finally, we could show that BKV agnoprotein negatively interferes with secretion of VSVG-EGFP reporter suggesting that agnoprotein may modulate exocytosis.
  
  
  CONCLUSIONS
  We have identified the first cellular interaction partner for BKV agnoprotein. The most N-terminal part of BKV agnoprotein is involved in the interaction with α-SNAP. Presence of BKV agnoprotein negatively interferes with secretion of VSVG-EGFP reporter.
authors.affiliation: Research Group of Host-Microbe Interactions, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway. mona.johannessen@uit.no
authors.forename: Mona
authors.initials: M
authors.lastname: Johannessen
authors.forename: Mari
authors.initials: M
authors.lastname: Walquist
authors.forename: Nancy
authors.initials: N
authors.lastname: Gerits
authors.forename: Marte
authors.initials: M
authors.lastname: Dragset
authors.forename: Anne
authors.initials: A
authors.lastname: Spang
authors.forename: Ugo
authors.initials: U
authors.lastname: Moens
mesh_terms: D000951:Antigens, Neoplasm / Q000737:chemistry; D001739:BK Virus / Q000378:metabolism*; D005089:Exocytosis; D016679:Genome, Viral; D049452:Green Fluorescent Proteins / Q000737:chemistry; D057809:HEK293 Cells; D006801:Humans; D007668:Kidney / Q000821:virology; D008562:Membrane Glycoproteins / Q000737:chemistry*; D008856:Microscopy, Fluorescence / Q000379:methods; D010957:Plasmids / Q000378:metabolism; D017434:Protein Structure, Tertiary; D052067:Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins / Q000737:chemistry*; D020798:Two-Hybrid System Techniques; D014759:Viral Envelope Proteins / Q000737:chemistry*; D014764:Viral Proteins / Q000737:chemistry*; D054334:Viral Regulatory and Accessory Proteins / Q000737:chemistry / Q000378:metabolism*; D000086082:Viroporin Proteins
chemical_list: D000951:Antigens, Neoplasm; D049452:Green Fluorescent Proteins; D008562:Membrane Glycoproteins; D052067:Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins; D014759:Viral Envelope Proteins; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins; C028391:G protein, vesicular stomatitis virus; C042559:agnoprotein, polyomavirus; D000086082:Viroporin Proteins; C485184:enhanced green fluorescent protein