Document Detail

ModA and ModB, two ADP-ribosyltransferases encoded by bacteriophage T4: catalytic properties and mutation analysis.
MedLine Citation:
PMID:  15489438     Owner:  NLM     Status:  MEDLINE    
Bacteriophage T4 encodes three ADP-ribosyltransferases, Alt, ModA, and ModB. These enzymes participate in the regulation of the T4 replication cycle by ADP-ribosylating a defined set of host proteins. In order to obtain a better understanding of the phage-host interactions and their consequences for regulating the T4 replication cycle, we studied cloning, overexpression, and characterization of purified ModA and ModB enzymes. Site-directed mutagenesis confirmed that amino acids, as deduced from secondary structure alignments, are indeed decisive for the activity of the enzymes, implying that the transfer reaction follows the Sn1-type reaction scheme proposed for this class of enzymes. In vitro transcription assays performed with Alt- and ModA-modified RNA polymerases demonstrated that the Alt-ribosylated polymerase enhances transcription from T4 early promoters on a T4 DNA template, whereas the transcriptional activity of ModA-modified polymerase, without the participation of T4-encoded auxiliary proteins for middle mode or late transcription, is reduced. The results presented here support the conclusion that ADP-ribosylation of RNA polymerase and of other host proteins allows initial phage-directed mRNA synthesis reactions to escape from host control. In contrast, subsequent modification of the other cellular target proteins limits transcription from phage early genes and participates in redirecting transcription to phage middle and late genes.
Bernd Tiemann; Reinhard Depping; Egle Gineikiene; Laura Kaliniene; Rimas Nivinskas; Wolfgang Rüger
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of bacteriology     Volume:  186     ISSN:  0021-9193     ISO Abbreviation:  J. Bacteriol.     Publication Date:  2004 Nov 
Date Detail:
Created Date:  2004-10-18     Completed Date:  2004-11-24     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  2985120R     Medline TA:  J Bacteriol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  7262-72     Citation Subset:  IM    
Ruhr Universität Bochum, Fakultät für Biologie, Arbeitsgruppe Molekulare Genetik, 44780 Bochum, Germany.
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MeSH Terms
ADP Ribose Transferases* / chemistry,  genetics,  isolation & purification,  metabolism
Amino Acid Sequence
Bacteriophage T4 / enzymology*,  physiology
Inclusion Bodies / enzymology
Molecular Sequence Data
Mutagenesis, Site-Directed
Protein Renaturation
Transcription, Genetic
Reg. No./Substance:
EC 2.4.2.-/ADP Ribose Transferases

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