Document Detail

Structural modelling and mutagenesis of human cytomegalovirus alkaline nuclease UL98.
MedLine Citation:
PMID:  21900421     Owner:  NLM     Status:  MEDLINE    
Human cytomegalovirus encodes an alkaline nuclease, UL98, that is highly conserved among herpesviruses and has both endonuclease (endo) and exonuclease (exo) activities. This protein is thought to be important for viral replication and therefore represents a potential target for antiviral development; however, little is known about its structure or role in viral replication. Comparative structural modelling was used to build a model of UL98 based on the known structure of shutoff and exonuclease protein from Kaposi's sarcoma-associated herpesvirus. The model predicts that UL98 residues D254, E278 and K280 represent the critical aspartic acid, glutamic acid and lysine active-site residues, respectively, while R164 and S252 correspond to residues proposed to bind the 5' phosphate of the DNA substrate. UL98 with an amino-terminal hexahistidine tag was expressed in Escherichia coli, purified by affinity chromatography and confirmed to have exo and endo activities. Amino acid substitutions D254A, E278A, K280A and S252A virtually eliminated exo and endo activities, whereas R164A retained full endo activity but only 10 % of the exo activity compared with the wild-type enzyme. A mutant virus lacking UL98 was viable but severely attenuated for replication, while one expressing UL98(R164A) replicated normally. These results confirm the utility of the model in representing the active-site region of UL98 and suggest a mechanism for the differentiation of endonuclease and exonuclease activities. These findings could facilitate the exploration of the roles of alkaline nucleases in herpesvirus replication and the rational design of inhibitors that target their enzymic activities.
Alison L Kuchta; Hardik Parikh; Yali Zhu; Glen E Kellogg; Deborah S Parris; Michael A McVoy
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2011-09-07
Journal Detail:
Title:  The Journal of general virology     Volume:  93     ISSN:  1465-2099     ISO Abbreviation:  J. Gen. Virol.     Publication Date:  2012 Jan 
Date Detail:
Created Date:  2011-12-20     Completed Date:  2012-02-14     Revised Date:  2013-10-23    
Medline Journal Info:
Nlm Unique ID:  0077340     Medline TA:  J Gen Virol     Country:  England    
Other Details:
Languages:  eng     Pagination:  130-8     Citation Subset:  IM    
Department of Pediatrics, Virginia Commonwealth University, Richmond, VA 23298, USA.
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MeSH Terms
Amino Acid Motifs
Amino Acid Sequence
Base Sequence
Catalytic Domain
Cell Line
Cytomegalovirus / chemistry,  enzymology*,  genetics,  physiology
Cytomegalovirus Infections / virology
Immediate-Early Proteins / chemistry*,  genetics*,  metabolism
Models, Molecular
Molecular Sequence Data
Virus Replication
Grant Support
Reg. No./Substance:
0/Immediate-Early Proteins; 0/UL98 protein, cytomegalovirus

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