Journal article
Phylogenomics Reveals a Diverse Rickettsiales Type IV Secretion System
Infection and immunity, Vol.78(5), pp.1809-1823
05/2010
Handle:
https://hdl.handle.net/2376/115966
PMCID: PMC2863512
PMID: 20176788
Abstract
With an obligate intracellular lifestyle,
Alphaproteobacteria
of the order
Rickettsiales
have inextricably coevolved with their various eukaryotic hosts, resulting in small, reductive genomes and strict dependency on host resources. Unsurprisingly, large portions of
Rickettsiales
genomes encode proteins involved in transport and secretion. One particular transporter that has garnered recent attention from researchers is the type IV secretion system (T4SS). Homologous to the well-studied archetypal
vir
T4SS of
Agrobacterium tumefaciens
, the
R
ickettsiales
v
ir
h
omolog (
rvh
) T4SS is characterized primarily by duplication of several of its genes and scattered genomic distribution of all components in several conserved islets. Phylogeny estimation suggests a single event of ancestral acquirement of the
rvh
T4SS, likely from a nonalphaproteobacterial origin. Bioinformatics analysis of over 30
Rickettsiales
genome sequences illustrates a conserved core
rvh
scaffold (lacking only a
virB5
homolog), with lineage-specific diversification of several components (
rvhB1
,
rvhB2
, and
rvhB9b
), likely a result of modifications to cell envelope structure. This coevolution of the
rvh
T4SS and cell envelope morphology is probably driven by adaptations to various host cells, identifying the transporter as an important target for vaccine development. Despite the genetic intractability of
Rickettsiales
, recent advancements have been made in the characterization of several components of the
rvh
T4SS, as well as its putative regulators and substrates. While current data favor a role in effector translocation, functions in DNA uptake and release and/or conjugation cannot at present be ruled out, especially considering that a mechanism for plasmid transfer in
Rickettsia
spp. has yet to be proposed.
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Details
- Title
- Phylogenomics Reveals a Diverse Rickettsiales Type IV Secretion System
- Creators
- Joseph J Gillespie - Virginia Bioinformatics Institute at Virginia Tech, Blacksburg, Virginia 24061Kelly A Brayton - Virginia Bioinformatics Institute at Virginia Tech, Blacksburg, Virginia 24061Kelly P Williams - Virginia Bioinformatics Institute at Virginia Tech, Blacksburg, Virginia 24061Marco A Quevedo Diaz - Virginia Bioinformatics Institute at Virginia Tech, Blacksburg, Virginia 24061Wendy C Brown - Virginia Bioinformatics Institute at Virginia Tech, Blacksburg, Virginia 24061Abdu F Azad - Virginia Bioinformatics Institute at Virginia Tech, Blacksburg, Virginia 24061Bruno W Sobral - Virginia Bioinformatics Institute at Virginia Tech, Blacksburg, Virginia 24061
- Publication Details
- Infection and immunity, Vol.78(5), pp.1809-1823
- Academic Unit
- Veterinary Microbiology and Pathology, Department of
- Publisher
- American Society for Microbiology (ASM)
- Identifiers
- 99900548295901842
- Language
- English
- Resource Type
- Journal article