Contractile injection systems of bacteriophages and related systems. Issue 1 (26th February 2018)

• Record Type: Journal Article
• Authors: Taylor, Nicholas M. I.; van Raaij, Mark J.; Leiman, Petr G.
• Is Part Of: Molecular microbiology. Volume 108:Issue 1(2018)
• Page Start: 6
• Page End: 15
• Publication Date: 2018-02-26
• Subjects: Molecular microbiology -- Periodicals; 572.829
• DOI: 10.1111/mmi.13921
• Languages: English
• ISSNs: 0950-382X

Abstract

Summary: Contractile tail bacteriophages, or myobacteriophages, use a sophisticated biomolecular structure to inject their genome into the bacterial host cell. This structure consists of a contractile sheath enveloping a rigid tube that is sharpened by a spike‐shaped protein complex at its tip. The spike complex forms the centerpiece of a baseplate complex that terminates the sheath and the tube. The baseplate anchors the tail to the target cell membrane with the help of fibrous proteins emanating from it and triggers contraction of the sheath. The contracting sheath drives the tube with its spiky tip through the target cell membrane. Subsequently, the bacteriophage genome is injected through the tube. The structural transformation of the bacteriophage T4 baseplate upon binding to the host cell has been recently described in near‐atomic detail. In this review we discuss structural elements and features of this mechanism that are likely to be conserved in all contractile injection systems (systems evolutionary and structurally related to contractile bacteriophage tails). These include the type VI secretion system (T6SS), which is used by bacteria to transfer effectors into other bacteria and into eukaryotic cells, and tailocins, a large family of contractile bacteriophage tail‐like compounds that includes the P. aeruginosa R‐type pyocins. Abstract : Bacteria and bacteriophages utilize a rigid tube‐contractile sheath mechanism for delivering proteins and DNA across the cell envelope. Here we describe conserved features of these contractile assemblies and propose their evolutionary pathway. The complexity of today's systems is a result of gene duplication and subsequent specialization of function.