Cryo-EM structure of a bacteriophage T4 gp24 bypass mutant: The evolution of pentameric vertex proteins in icosahedral viruses

ArticleinJournal of Structural Biology 154(3):255-9 · July 2006with11 Reads
DOI: 10.1016/j.jsb.2006.01.008 · Source: PubMed
Abstract
Many large viral capsids require special pentameric proteins at their fivefold vertices. Nevertheless, deletion of the special vertex protein gene product 24 (gp24) in bacteriophage T4 can be compensated by mutations in the homologous major capsid protein gp23. The structure of such a mutant virus, determined by cryo-electron microscopy to 26 angstroms, shows that the gp24 pentamers are replaced by mutant major capsid protein (gp23) pentamers at the vertices, thus re-creating a viral capsid prior to the evolution of specialized major capsid proteins and vertex proteins. The mutant gp23* pentamer is structurally similar to the wild-type gp24* pentamer but the insertion domain is slightly more distant from the gp23* pentamer center. There are additional SOC molecules around the gp23* pentamers in the mutant virus that were not present around the gp24* pentamers in the wild-type virus.
    • "All these viruses used a slightly different protein that folded into a single jelly-roll and assembled as a pentamer. Similarly the T4 phage, whose capsid is constructed out of HK97 hexamers (gene product gp23), also has a homologous but different protein (gp24) at the five-fold vertices [112, 113]. Furthermore, in the case of the double jelly-roll structures, as a consequence of having only three-fold rather than six-fold symmetry there is a slight difference in the assembly when a hexamer is rotated by 60°. "
    [Show abstract] [Hide abstract] ABSTRACT: I describe my gradually evolving role as a scientist from my birth in Frankfurt (Germany) to my education in the UK, my post-doc years and my experiences as an independent investigator at Purdue University1. I discuss the significance of my post-doctoral work in Minnesota where I had my first encounter with an electronic computer and subsequently in Cambridge where I participated in the first structure determination of proteins. After six years back in England my family moved to Indiana (USA) where my home remains to this day. At Purdue University I first studied the structure of enzymes and in the process I discovered the organization and slow evolution of protein domains, each with a specific function. With this success I started what had been on my mind already for a long time, namely the structural analysis of viruses. Initially we studied plant viruses but then switched to small RNA animal viruses, discovering that some plant and animal RNA viruses have closely similar structures and therefore presumably had a common evolutionary origin. Next I became interested in somewhat larger viruses that had lipid membrane envelopes. In turn that has led to the study of very large dsDNA viruses as big as small bacteria as well as studies of bacterial viruses that require complex molecular motors for different parts of their life cycle. While developing crystallographic techniques for the study of viruses it has become progressively more apparent that electron microscopy is an important new tool that is likely to eclipse x-ray crystallography in the next decade.
    Article · Sep 2014
    • "In Herpes and most tdphage , a single major capsid protein (MCP) accounts for both structures [10,11]. Phage T4 does have distinct hexon and penton proteins, but these are closely related and are thought to have arisen through gene duplication [12]. Apart from this underlying similarity, the capsids of Herpes and td-phage display a multiplicity of architectures. "
    [Show abstract] [Hide abstract] ABSTRACT: Structural information can inform our understanding of virus origins and evolution. The herpesviruses and tailed bacteriophages constitute two large families of dsDNA viruses which infect vertebrates and prokaryotes respectively. A relationship between these disparate groups was initially suggested by similarities in their capsid assembly and DNA packaging strategies. This relationship has now been confirmed by a range of studies that have revealed common structural features in their capsid proteins, and similar organizations and sequence conservation in their DNA packaging machinery and maturational proteases. This concentration of conserved traits in proteins involved in essential and primordial capsid/packaging functions is evidence that these structures are derived from an ancient, common ancestor and is in sharp contrast to the lack of such evidence for other virus functions.
    Full-text · Article · Apr 2014
    • "Although both are present in the wild-type T4 phage, a mutant gp23 can form both hexameric and pentameric capsomers, producing a capsid that contains only one type of capsid protein414243. These two proteins share 21% sequence similarity and probably occurred as the result of gene duplication [42,44]. Many eukaryotic viruses, like herpesvirus, adenovirus, picornaviruses, PBCV-1 and others, code for more than one capsid protein [45]. "
    [Show abstract] [Hide abstract] ABSTRACT: Bacteriophages have been a model system to study assembly processes for over half a century. Formation of infectious phage particles involves specific protein-protein and protein-nucleic acid interactions, as well as large conformational changes of assembly precursors. The sequence and molecular mechanisms of phage assembly have been elucidated by a variety of methods. Differences and similarities of assembly processes in several different groups of bacteriophages are discussed in this review. The general principles of phage assembly are applicable to many macromolecular complexes.
    Full-text · Article · Mar 2011
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