Ectodomain structure of per os infectivity factor 5

Experimental Data Snapshot

  • Resolution: 2.20 Å
  • R-Value Free: 0.244 
  • R-Value Work: 0.199 
  • R-Value Observed: 0.201 

wwPDB Validation   3D Report Full Report

This is version 1.1 of the entry. See complete history


Structural Characterization of Per Os Infectivity Factor 5 (PIF5) Reveals the Essential Role of Intramolecular Interactions in Baculoviral Oral Infectivity.

Li, Z.Zhang, H.Li, Z.Fu, Y.Wang, X.Li, J.Wang, K.Wang, Z.Zhang, T.Wang, M.Hu, Z.Cao, S.

(2022) J Virol 96: e0080622-e0080622

  • DOI: https://doi.org/10.1128/jvi.00806-22
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Baculoviruses initiate oral infection in the highly alkaline midgut of insects via a group of envelope proteins called per os infectivity factors (PIFs). To date, no high-resolution structural information has been reported for any PIF. Here, we present the crystal structure of the PIF5 ectodomain (PIF5e) from Autographa californica multiple nucleopolyhedrovirus (AcMNPV) at a 2.2-Å resolution. It revealed an open cavity between the N-terminal E1 domain and the C-terminal E2 domain and a cysteine-rich region with three pairs of disulfide bonds in the E2 domain. Multiple conserved intramolecular interactions within PIF5 are essential for maintaining its tertiary structure. Two conserved arginines (Arg8 and Arg74) play critical roles in E1-E2 interactions, and mutagenesis analysis supported their crucial role in oral infection. Importantly, the reduction in the oral infectivity of the Arg8, Arg74, or cysteine mutant viruses was related to the proteolytic cleavage of PIF5 by the endogenous protease embedded in occlusion bodies during alkaline treatment. This suggested that the structural stability of PIF5 under physiological conditions in the insect midgut is critical for baculoviral oral infectivity. IMPORTANCE Per os infection mediated by PIFs is the highly complex mechanism by which baculoviruses initiate infection in insects. Previous studies revealed that multiple PIF proteins form a large PIF complex on the envelope of virions, while PIF5 functions independently of the PIF complex. Here, we report the crystal structure of AcMNPV PIF5e, which, to our knowledge, is the first atomic structure reported for a PIF protein. The structure revealed the precise locations of three previously proposed disulfide bonds and other conserved intramolecular interactions, which are important for the structural stability of PIF5 and are also essential for oral infectivity. These findings advance our understanding of the molecular mechanism of baculovirus oral infection under alkaline conditions.

  • Organizational Affiliation

    CAS Key Laboratory of Special Pathogens, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, People's Republic of China.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Per os infectivity factor 5378Autographa californica multiple nucleopolyhedrovirusMutation(s): 0 
Gene Names: Ac-odv-e56LO84_150
Find proteins for P41705 (Autographa californica nuclear polyhedrosis virus)
Explore P41705 
Go to UniProtKB:  P41705
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP41705
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.20 Å
  • R-Value Free: 0.244 
  • R-Value Work: 0.199 
  • R-Value Observed: 0.201 
  • Space Group: P 21 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 68.173α = 90
b = 92.36β = 90
c = 52.646γ = 90
Software Package:
Software NamePurpose
XDSdata reduction
PHENIXmodel building
Cootmodel building

Structure Validation

View Full Validation Report

Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
Chinese Academy of SciencesChinaQYZDJ-SSW-SMC021

Revision History  (Full details and data files)

  • Version 1.0: 2022-06-22
    Type: Initial release
  • Version 1.1: 2022-08-10
    Changes: Database references