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.
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.
Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autónoma de Madrid, 28049 Cantoblanco, Madrid, Spain.
Cristina
C
Sánchez-Martínez
Esther
E
Grueso
Miles
M
Carroll
Jean
J
Rommelaere
José M
JM
Almendral
D000818:Animals; D036022:Capsid Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002467:Cell Nucleus / Q000821:virology; D011992:Endosomes / Q000821:virology; D051379:Mice; D008915:Minute Virus of Mice / Q000502:physiology*; D008954:Models, Biological; D017434:Protein Structure, Tertiary; D019065:Virus Assembly; D053586:Virus Internalization
D036022:Capsid Proteins