As our understanding of mobile genetic elements continues to grow we are gaining a deeper appreciation of their importance in shaping the bacterial genome and in the properties they confer to their bacterial hosts. These include, but are by no means limited to, resistance to antibiotics, and heavy metals, toxin production and increased virulence, production of antibiotics and the ability to utilize a diverse range of metabolic substrates. We are also gaining an understanding of diversity of these elements and their interactions with each other; a property which continually complicates any attempt to classify them. We are learning more about the molecular mechanisms by which they translocate to new genomic sites both within genomes and between different bacteria. This book provides a timely, state of the art update on the properties of an important selection of different bacterial integrative mobile genetic elements and the myriad of different ways in which they move and influence the biology of the host bacterium. The chapters are all written by authors who have undertaken pioneering work in their respective fields, making this book vital reading for all who are interested in the biology of bacteria and the mobile elements they carry.
Author(s): Adam P. Roberts, Peter Mullany
Series: Molecular Biology Intelligence Unit
Publisher: CRC Press
Year: 2013
Language: English
Pages: 335
City: Boca Raton
Cover
Title
Copyright
Dedication
About the Editors
About the Editors
Contents
Editors
Preface
Acknowledgments
1. Transposon Tn7
Introduction
Tn7 Transposition Functions
Target Selection in the TnsABC+D Transposition Pathway
Target Selection in the TnsABC+E Transposition Pathway
Recognition of a Positive Target Signal by TnsC
Target Immunity
Expansion of the Tn7 Family by Virtue of Vertical and Horizontal Transposition
Internal Networking of the Core Machinery
Assembly of the Transpososome for TnsABC+D Transposition
Tn7 as a Genetic Tool
Conclusion
2. Mercury Resistance Transposons
Introduction
Mercury Resistance Transposons of Gram-Negative Bacteria
Tn21 Subgroup of Tn3 Family Transposons
Mercury Resistance Transposons Belonging to Tn3 Family
Tn5053 Family Transposons
Tn5042-Like Transposons
Mercury Resistance Transposons of Gram-Positive Bacteria
Recombinant Transposons and Their Formation Mechanisms
Distribution of mer Transposons and Their Horizontal Transfer
Conclusion
3. Integrons: Antibiotic Resistance Evolution and Beyond
Introduction
Integrons: Emergence of a New Discrete Genetic Element
The Integron Site-Specific Recombination System
The Mobilisation of Integrons and the Spread of Antibiotic Resistance
The IntI Subfamily of Recombinases
Gene Cassette Structure
The Recombination Sites and Reaction—attI and attC
Chromosomal Integrons
Adaptive Role of Integrons and Cassettes
Gene Cassette Diversity—Metagenomic Studies
Gene Cassette Diversity—Functional Gene Content Studies
Use of Chromosomal Integron-Cassette Arrays in Phylogenetics
Conclusion
4. Inteins and Introns
Introduction
Group II Introns
Mobility Mechanisms for Group II Introns
Evolution of Group II Introns
Applications of Group II Introns
Group I Introns
Inteins
Applications of Inteins
Insertion Sites of Introns and Inteins
Homing Endonucleases
The Homing Cycle
Acquisition of New Functions
Conclusion/Outlook
5. Restriction-Modification Systems as Mobile Epigenetic Elements
Introduction: Restriction-Modification Systems in Epigenetic Conflicts
Abundance of RM Systems
Types of Restriction Systems
Gene Organization
Mobility of RM Systems Revealed from Molecular Evolutionary Analyses
RM Systems on Mobile Genetic Elements
RM Systems as Mobile Genetic Elements
Attack on the Host Bacterial Genome: Type II RM Systems
Attack on the Host Bacterial Genome: Type IV Restriction Systems
Attack on the Host Bacterial Genome: Type I RM Systems
Anti-Restriction Systems
RM Systems and Genome Rearrangements
Impact on Genome Evolution
Domain Sequence Movement in the Specificity Subunit
Gene Regulation
Conclusion and Perspective
6. Mobile Genetic Elements in the Genus Bacteroides, and Their Mechanism(s) of Dissemination
Introduction
Mobile Genetic Elements in the Bacteroides
How are Mobile Elements Transferred within and from Bacteroides Spp?
Combating Antibiotic Resistance by Targeting Bacterial Conjugation
Conclusion
7. Mobilisable Genetic Elements from the Clostridia
Introduction
Mobile Elements in the Clostridia
The Tn4451/3 Family of Mobilisable Transposons
The Lincomycin Resistance Element tISCpe8
The Erythromycin Resistance Element Tn5398
Conclusion
8. pSAM2, a Paradigm for a Family of Actinomycete Integrative and Conjugative Elements
Introduction
Overview of pSAM2 Functions
Site-Specific Excision/Integration
Replication
Transfer
Regulation
Other Genes
Host Range
pSAM2-Like Elements
Genetic Tools Derived from pSAM2
Conclusion
9. The Tn916/Tn1545 Family of Conjugative Transposons
Introduction
The Functions of the Transposon Encoded Proteins by Module
Variations on the Tn916 Theme
Conclusion
10. Tn1549 and Closely Related Elements
Introduction
Structure of Tn1549
The Resistance Module: The vanB Operon
The Transposition Module
The Conjugation Module
Fitness Cost ot VanB-Type Resistance in Enterococcil
Conclusion
11. The Tn4371 ICE Family of Bacterial Mobile Genetic Elements
Introduction
Taxonomy of Tn4371-Like ICEs and Their Hosts
Integration and Excision (IntMod)
Stability and Maintenance Genes (StaMod)
The Accessory Genes (AccMod)
Transfer Genes and TraMod
Conclusion
12. The Integrative and Conjugative Element ICEBs1 of Bacillus subtilis
Introduction to ICEBs1
Regulation of Induction of ICEBs1
DNA Processing Events Prior to Transfer
DNA Transfer through the ICEBs1 Mating Machinery
Cell Biology of Mating of ICEBs1
Integration of ICEBs1 on the Chromosome
Immunity
Conclusion and Future Directions
13. Integrating Conjugative Elements of the SXT/R391 Family
Introduction
SXT/R391 ICEs Share a Common Backbone
Variable Regions and Diversity of Encoded Functions
Entry Exclusion: Two Distinct Groups Coexist in SXI/R391 ICES
Plasticity and Evolution of SXT/R391 ICEs
Mobilization of Plasmids, Mobilizable Genomic Islands and Chromosomal DNA
Conclusion
14. Excision and Transfer of Bacteroides Conjugative Integrated Elements
Introduction
Excision of CTnDOT
Regulation of CTnDOT Excision
Transfer of CTnDOT
Excision of Other Bacteroides Integrated Mobile Elements
Conclusion
15. Integrative and Conjugative Elements Encoding DDE Transposases
Introduction
Organization and Diversity of TnGBS1 and Related Transposons
Organization and Diversity of TnGBS2 and Related Elements
Organization of ICE6013
The Transposition Module
Conclusion
16. The clc Element and Related Genomic Islands in Proteobacteria
Introduction
Genetic Structure of ICEclc
GEI/ICE Related to ICEclc
Integrase Mediates the Integration/Excision Reaction
Transfer System of ICEclc
Regulation of ICEclc Transfer
Effects of ICEclc on the Host Cell
Conclusion
17. Pathogenicity Island Evolution: A Distinct New Class of Integrative Element or a Mosaic of Other Elements?
Original Definition of a Pathogenicity Island (PAI)
The Discovery and Elucidation of the First PAIs
Pathogenicity Island Encoded Virulence Factors
The PAI Concept is Broadened
An Alternative Hypothesis of Pathogenicity Island Evolution
Pathogenicity Island Excision from the Host Chromosome
Conclusion
18. Staphylococcal Cassette Chromosome (SCC): A Unique Gene Transfer System in Staphylococci
Introduction
SCCmec is a SCC Specialized for the Transfer of Methicillin Resistance
Identification of mecA Gene and Its Homoloes
Structure of SCCmec: The mec Gene Complexes
Origin of mec Gene Complex
ccrs are Responsible for the Mobility of SCCmecs
SCCmec as a Vehicle for Multi-Drug Resistance
Horizontal Transfer and Molecular Evolution of SCCmec
Shaping a New SCCmec: Recombination and Fusion of SCC Elements
Conclusion
Index
