PDBsum entry 4jpp

Viral protein

PDB id: 4jpp

Contents

Protein chains

127 a.a.

Waters ×518

References listed in PDB file

Key reference

• Title: Icosahedral bacteriophage ΦX174 forms a tail for DNA transport during infection.
• Authors: L.Sun, L.N.Young, X.Zhang, S.P.Boudko, A.Fokine, E.Zbornik, A.P.Roznowski, I.J.Molineux, M.G.Rossmann, B.A.Fane.
• Ref.: Nature, 2014, 505, 432-435. [DOI no: 10.1038/nature12816]
• PubMed id: 24336205

Abstract

Prokaryotic viruses have evolved various mechanisms to transport their genomes across bacterial cell walls. Many bacteriophages use a tail to perform this function, whereas tail-less phages rely on host organelles. However, the tail-less, icosahedral, single-stranded DNA ΦX174-like coliphages do not fall into these well-defined infection processes. For these phages, DNA delivery requires a DNA pilot protein. Here we show that the ΦX174 pilot protein H oligomerizes to form a tube whose function is most probably to deliver the DNA genome across the host's periplasmic space to the cytoplasm. The 2.4 Å resolution crystal structure of the in vitro assembled H protein's central domain consists of a 170 Å-long α-helical barrel. The tube is constructed of ten α-helices with their amino termini arrayed in a right-handed super-helical coiled-coil and their carboxy termini arrayed in a left-handed super-helical coiled-coil. Genetic and biochemical studies demonstrate that the tube is essential for infectivity but does not affect in vivo virus assembly. Cryo-electron tomograms show that tubes span the periplasmic space and are present while the genome is being delivered into the host cell's cytoplasm. Both ends of the H protein contain transmembrane domains, which anchor the assembled tubes into the inner and outer cell membranes. The central channel of the H-protein tube is lined with amide and guanidinium side chains. This may be a general property of viral DNA conduits and is likely to be critical for efficient genome translocation into the host.