An activation domain of plasmid R1 TraI protein delineates stages of gene transfer initiation

Summary Bacterial conjugation is a form of type IV secretion that transports protein and DNA to recipient cells. Specific bacteriophage exploit the conjugative pili and cell envelope spanning protein machinery of these systems to invade bacterial cells. Infection by phage R17 requires F‐like pili an...

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Bibliographic Details
Published in:Molecular microbiology 2011-12, Vol.82 (5), p.1071-1085
Main Authors: Lang, Silvia, Kirchberger, Paul C., Gruber, Christian J., Redzej, Adam, Raffl, Sandra, Zellnig, Guenther, Zangger, Klaus, Zechner, Ellen L.
Format: Article
Language:English
Subjects:
Bacteriolysis
Conjugation, Genetic
Cytoplasm
Deoxyribonucleic acid
DNA
DNA Helicases - metabolism
Escherichia coli - genetics
Escherichia coli - metabolism
Escherichia coli - virology
Escherichia coli Proteins - metabolism
Fimbriae, Bacterial - metabolism
Gene Transfer, Horizontal
Genes
Levivirus - genetics
Levivirus - physiology
Membrane Proteins - metabolism
Models, Biological
Phage r17
Plasmids
Plasmids - genetics
Plasmids - metabolism
Protein Binding
Protein Interaction Mapping
Protein Multimerization
Proteins
Replication Origin
Signal transduction
Virus Internalization
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Summary:Summary Bacterial conjugation is a form of type IV secretion that transports protein and DNA to recipient cells. Specific bacteriophage exploit the conjugative pili and cell envelope spanning protein machinery of these systems to invade bacterial cells. Infection by phage R17 requires F‐like pili and coupling protein TraD, which gates the cytoplasmic entrance of the secretion channel. Here we investigate the role of TraD in R17 nucleoprotein uptake and find parallels to secretion mechanisms. The relaxosome of IncFII plasmid R1 is required. A ternary complex of plasmid oriT, TraD and a novel activation domain within the N‐terminal 992 residues of TraI contributes a key mechanism involving relaxase‐associated properties of TraI, protein interaction and the TraD ATPase. Helicase‐associated activities of TraI are dispensable. These findings distinguish for the first time specific protein domains and complexes that process extracellular signals into distinct activation stages in the type IV initiation pathway. The study also provided insights into the evolutionary interplay of phage and the plasmids they exploit. Related plasmid F adapted to R17 independently of TraI. It follows that selection for phage resistance drives not only variation in TraA pilins but diversifies TraD and its binding partners in a plasmid‐specific manner.
ISSN:0950-382X
1365-2958
DOI:10.1111/j.1365-2958.2011.07872.x