Characterization of a trifunctional mimivirus mRNA capping enzyme and crystal structure of the RNA triphosphatase domain Journal Article

  

Authors:	Benarroch, D.; Smith, P.; Shuman, S.
Article Title:	Characterization of a trifunctional mimivirus mRNA capping enzyme and crystal structure of the RNA triphosphatase domain
Abstract:	The RNA triphosphatase (RTPase) components of the mRNA capping apparatus are a bellwether of eukaryal taxonomy. Fungal and protozoal RTPases belong to the triphosphate tunnel metalloenzyme (TTM) family, exemplified by yeast Cet1. Several large DNA viruses encode metal-dependent RTPases unrelated to the cysteinyl-phosphatase RTPases of their metazoan host organisms. The origins of DNA virus RTPases are unclear because they are structurally uncharacterized. Mimivirus, a giant virus of amoeba, resembles poxviruses in having a trifunctional capping enzyme composed of a metal-dependent RTPase module fused to guanylyltransferase (GTase) and guanine-N7 methyltransferase domains. The crystal structure of mimivirus RTPase reveals a minimized tunnel fold and an active site strikingly similar to that of Cet1. Unlike homodimeric fungal RTPases, mimivirus RTPase is a monomer. The mimivirus TTM-type RTPase-GTase fusion resembles the capping enzymes of amoebae, providing evidence that the ancestral large DNA virus acquired its capping enzyme from a unicellular host. © 2008 Elsevier Ltd. All rights reserved.
Keywords:	unclassified drug; mutation; nonhuman; protein domain; protein; rna triphosphatase; acid anhydride hydrolases; rna; methyltransferase; methyltransferases; amino acid sequence; molecular sequence data; messenger rna; virus rna; enzyme analysis; dna viruses; sequence alignment; amoeba (genus); eukaryota; mimivirus; crystal structure; models, molecular; crystallography, x-ray; protein structure, tertiary; binding sites; protein folding; structure analysis; enzyme structure; protein tertiary structure; monomer; viral proteins; enzyme active site; metazoa; isoenzyme; nucleotidyltransferases; rna capping enzyme; transferase; fungal enzyme; homodimer; protein cet1; virus enzyme; amoeba; dna virus
Journal Title:	Structure
Volume:	16
Issue:	4
ISSN:	0969-2126
Publisher:	Cell Press
Date Published:	2008-04-08
Start Page:	501
End Page:	512
Language:	English
DOI:	10.1016/j.str.2008.01.009
PUBMED:	18400173
PROVIDER:	scopus
DOI/URL:	http://www.scopus.com/inward/record.url?eid=2-s2.0-41449108933&partnerID=40&md5=e3c2c01f16b8cdc1c1f119c98b1f4284
Notes:	--- - "Cited By (since 1996): 9" - "Export Date: 17 November 2011" - "CODEN: STRUE" - "Source: Scopus"

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