Essential role of the unordered VP2 n-terminal domain of the parvovirus MVM capsid in nuclear assembly and endosomal enlargement of the virion fivefold channel for cell entry

• Published in: Virology (New York, N.Y.) N.Y.), 2012-10, Vol.432 (1), p.45-56
• Main Authors: Sánchez-Martínez, Cristina, Grueso, Esther, Carroll, Miles, Rommelaere, Jean, Almendral, José M
• Format: Article
• Language: English
• Subjects: 60 APPLIED LIFE SCIENCES; Animals; ANTIBODIES; Assembly; Capsid cleavage; Capsid Proteins - genetics; Capsid Proteins - metabolism; Cell entry; Cell Line; Cell Nucleus - virology; CLEAVAGE; Endosomes - virology; Infectious Disease; INFECTIVITY; Mice; Minute Virus of Mice - physiology; Models, Biological; Parvovirus; Peptide insertion; PEPTIDES; Protein Structure, Tertiary; Virus Assembly; Virus Internalization; Virus traffick; VIRUSES
• ISSN: 0042-6822; 1096-0341
• DOI: 10.1016/j.virol.2012.05.025

Abstract The unordered N-termini of parvovirus capsid proteins (Nt) are translocated through a channel at the icosahedral five-fold axis to serve for virus traffick. Heterologous peptides were genetically inserted at the Nt of MVM to study their functional tolerance to manipulations. Insertion of a 5T4-single-chain antibody at VP2-Nt (2Nt) yielded chimeric capsid subunits failing to enter the nucleus. The VEGFR2-binding peptide (V1) inserted at both 2Nt and VP1-Nt efficiently assembled in virions, but V1 disrupted VP1 and VP2 entry functions. The VP2 defect correlated with restricted externalization of V1-2Nt out of the coat. The specific infectivity of MVM and wtVP-pseudotyped mosaic MVM-V1 virions, upon heating and/or partial 2Nt cleavage, demonstrated that some 2Nt domains become intracellularly translocated out of the virus shell and cleaved to initiate entry. The V1 insertion defines a VP2-driven endosomal enlargement of the channel as an essential structural rearrangement performed by the MVM virion to infect.