title: Differential modulation of prM cleavage, extracellular particle distribution, and virus infectivity by conserved residues at nonfurin consensus positions of the dengue virus pr-M junction.
abstract: In the generation of flavivirus particles, an internal cleavage of the envelope glycoprotein prM by furin is required for the acquisition of infectivity. Unlike cleavage of the prM of other flaviviruses, cleavage of dengue virus prM is incomplete in many cell lines; the partial cleavage reflects the influence of residues at furin nonconsensus positions of the pr-M junction, as flaviviruses share basic residues at positions P1, P2, and P4, recognized by furin. In this study, viruses harboring the alanine-scanning and other multiple-point mutations of the pr-M junction were generated, employing a dengue virus background that exhibited 60 to 70% prM cleavage and a preponderance of virion-sized extracellular particles. Analysis of prM and its cleavage products in viable mutants revealed a cleavage-suppressive effect at the conserved P3 Glu residue, as well as the cleavage-augmenting effects at the P5 Arg and P6 His residues, indicating an interplay between opposing modulatory influences mediated by these residues on the cleavage of the pr-M junction. Changes in the prM cleavage level were associated with altered proportions of extracellular virions and subviral particles; mutants with reduced cleavage were enriched with subviral particles and prM-containing virions, whereas the mutant with enhanced cleavage was deprived of these particles. Alterations of virus multiplication were detected in mutants with reduced prM cleavage and were correlated with their low specific infectivities. These findings define the functional roles of charged residues located adjacent to the furin consensus sequence in the cleavage of dengue virus prM and provide plausible mechanisms by which the reduction in the pr-M junction cleavability may affect virus replication.
authors: Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
authors: Jiraphan
authors: J
authors: Junjhon
authors: Matthawee
authors: M
authors: Lausumpao
authors: Sunpetchuda
authors: S
authors: Supasa
authors: Sansanee
authors: S
authors: Noisakran
authors: Adisak
authors: A
authors: Songjaeng
authors: Prakaimuk
authors: P
authors: Saraithong
authors: Kridsada
authors: K
authors: Chaichoun
authors: Utaiwan
authors: U
authors: Utaipat
authors: Poonsook
authors: P
authors: Keelapang
authors: Amornrat
authors: A
authors: Kanjanahaluethai
authors: Chunya
authors: C
authors: Puttikhunt
authors: Watchara
authors: W
authors: Kasinrerk
authors: Prida
authors: P
authors: Malasit
authors: Nopporn
authors: N
authors: Sittisombut
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D009033:Culicidae; D003716:Dengue Virus / Q000235:genetics / Q000502:physiology*; D045683:Furin / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D017354:Point Mutation; D014759:Viral Envelope Proteins / Q000235:genetics / Q000378:metabolism*; D014771:Virion / Q000378:metabolism / Q000648:ultrastructure; D019065:Virus Assembly
chemical_list: D014759:Viral Envelope Proteins; C074932:prM protein, Flavivirus; D045683:Furin