A distinct and divergent lineage of genomic island-associated Type IV Secretion Systems in Legionella

Wee, Bryan A., Woolfit, Megan, Beatson, Scott A. and Petty, Nicola K. (2013) A distinct and divergent lineage of genomic island-associated Type IV Secretion Systems in Legionella. PloS One, 8 12: 1-13. doi:10.1371/journal.pone.0082221


Author Wee, Bryan A.
Woolfit, Megan
Beatson, Scott A.
Petty, Nicola K.
Title A distinct and divergent lineage of genomic island-associated Type IV Secretion Systems in Legionella
Formatted title
A distinct and divergent lineage of genomic island-associated Type IV Secretion Systems in Legionella
Journal name PloS One   Check publisher's open access policy
ISSN 1932-6203
Publication date 2013-12-16
Year available 2013
Sub-type Article (original research)
DOI 10.1371/journal.pone.0082221
Open Access Status DOI
Volume 8
Issue 12
Start page 1
End page 13
Total pages 13
Place of publication San Francisco, United States
Publisher Public Library of Science
Language eng
Formatted abstract
Legionella encodes multiple classes of Type IV Secretion Systems (T4SSs), including the Dot/Icm protein secretion system that is essential for intracellular multiplication in amoebal and human hosts. Other T4SSs not essential for virulence are thought to facilitate the acquisition of niche-specific adaptation genes including the numerous effector genes that are a hallmark of this genus. Previously, we identified two novel gene clusters in the draft genome of Legionella pneumophila strain 130b that encode homologues of a subtype of T4SS, the genomic island-associated T4SS (GI-T4SS), usually associated with integrative and conjugative elements (ICE). In this study, we performed genomic analyses of 14 homologous GI-T4SS clusters found in eight publicly available Legionella genomes and show that this cluster is unusually well conserved in a region of high plasticity. Phylogenetic analyses show that Legionella GI-T4SSs are substantially divergent from other members of this subtype of T4SS and represent a novel clade of GI-T4SSs only found in this genus. The GI-T4SS was found to be under purifying selection, suggesting it is functional and may play an important role in the evolution and adaptation of Legionella. Like other GI-T4SSs, the Legionella clusters are also associated with ICEs, but lack the typical integration and replication modules of related ICEs. The absence of complete replication and DNA  pre-processing modules, together with the presence of Legionella-specific regulatory elements, suggest the Legionella GI-T4SS-associated ICE is unique and may employ novel mechanisms of regulation, maintenance and excision. The Legionella GI-T4SS cluster was found to be associated with several cargo genes, including numerous antibiotic resistance and virulence factors, which may confer a fitness benefit to the organism. The in-silico characterisation of this new T4SS furthers our understanding of the diversity of secretion systems involved in the frequent horizontal gene transfers that allow Legionella to adapt to and exploit diverse environmental niches.
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Article number e82221.

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2014 Collection
School of Chemistry and Molecular Biosciences
 
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Created: Fri, 10 Jan 2014, 20:58:41 EST by Miss Abigail Downie on behalf of School of Chemistry & Molecular Biosciences