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Structure. 2018 Jul 3;26(7):936-947.e3. doi: 10.1016/j.str.2018.04.008. Epub 2018 May 17.

A Hyperthermophilic Phage Decoration Protein Suggests Common Evolutionary Origin with Herpesvirus Triplex Proteins and an Anti-CRISPR Protein.

Author information

1
Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01655, USA.
2
RNA Therapeutics Institute, Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01655, USA.
3
Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01655, USA. Electronic address: brian.kelch@umassmed.edu.

Abstract

Virus capsids are protein shells that protect the viral genome from environmental assaults, while maintaining the high internal pressure of the tightly packaged genome. To elucidate how capsids maintain stability under harsh conditions, we investigated the capsid components of the hyperthermophilic phage P74-26. We determined the structure of capsid protein gp87 and show that it has the same fold as decoration proteins in many other phages, despite lacking significant sequence homology. We also find that gp87 is significantly more stable than mesophilic homologs. Our analysis of the gp87 structure reveals that the core "β tulip" domain is conserved in trimeric capsid components across numerous double-stranded DNA viruses, including Herpesviruses. Moreover, this β barrel domain is found in anti-CRISPR protein AcrIIC1, suggesting a mechanism for the evolution of this Cas9 inhibitor. Our work illustrates the principles for increased stability of gp87, and extends the evolutionary reach of the β tulip domain.

KEYWORDS:

anti-CRISPR protein; capsid decoration protein; double-stranded DNA virus; viral proteins

PMID:
29779790
PMCID:
PMC6277972
DOI:
10.1016/j.str.2018.04.008
[Indexed for MEDLINE]
Free PMC Article

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