Publication Date:
2013-12-18
Description:
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 PhiX174-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 PhiX174 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 A resolution crystal structure of the in vitro assembled H protein's central domain consists of a 170 A-long alpha-helical barrel. The tube is constructed of ten alpha-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.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sun, Lei -- Young, Lindsey N -- Zhang, Xinzheng -- Boudko, Sergei P -- Fokine, Andrei -- Zbornik, Erica -- Roznowski, Aaron P -- Molineux, Ian J -- Rossmann, Michael G -- Fane, Bentley A -- England -- Nature. 2014 Jan 16;505(7483):432-5. doi: 10.1038/nature12816. Epub 2013 Dec 15.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, USA [2]. ; 1] School of Plant Sciences and the BIO5 Institute, University of Arizona, Tucson, Arizona 85721, USA [2]. ; 1] Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, USA [2] The Research Department, Shriner's Hospital for Children, Portland, Oregon 97239, USA. ; Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, USA. ; School of Plant Sciences and the BIO5 Institute, University of Arizona, Tucson, Arizona 85721, USA. ; Molecular Genetics and Microbiology, Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24336205" target="_blank"〉PubMed〈/a〉
Keywords:
Bacteriophage phi X 174/*chemistry/*metabolism/ultrastructure
;
Biological Transport
;
Cryoelectron Microscopy
;
Crystallography, X-Ray
;
Cytoplasm/metabolism/ultrastructure/virology
;
DNA, Viral/*metabolism/ultrastructure
;
Escherichia coli/cytology/ultrastructure/*virology
;
Genome, Viral
;
Models, Molecular
;
Periplasm/metabolism/ultrastructure
;
Protein Structure, Secondary
;
Protein Structure, Tertiary
;
Viral Proteins/chemistry/metabolism/ultrastructure
;
*Virus Assembly
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
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