Linked Life Data

17975091

Source:http://linkedlifedata.com/resource/pubmed/id/17975091

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
Pt 11
pubmed:dateCreated
2007-11-2
pubmed:abstractText
Legionella pneumophila is an opportunistic pathogen that in the environment colonizes biofilms and replicates within amoebae. The bacteria employ the intracellular multiplication/defective organelle trafficking (Icm/Dot) type IV secretion system to grow intracellularly in a specific vacuole. Using Acanthamoeba castellanii as a host cell, we have previously identified lcsC (Legionella cytotoxic suppressor), a paralogue of the lipid A disaccharide synthase lpxB, as a cytotoxic factor of L. pneumophila. A bioinformatic analysis of the genome revealed that L. pneumophila is unique in harbouring two paralogues of lpxB and two and three paralogues of the lipid A biosynthesis acyltransferases lpxA and lpxD, respectively. LcsC (lpxB1) forms a transcriptional unit with gnnA, encoding a putative UDP-GlcNAc oxidase in the biosynthetic pathway leading to 3-aminoglucosamine analogues of lipid A. LpxB2 clusters with lpxD2, lpxA2 and lpxL paralogues, encoding secondary acyltransferases. LcsC/lpxB1 and lpxB2 were found to partially complement the growth defect of an Escherichia coli lpxB conditional mutant strain, indicating that both corresponding enzymes possess lipid A disaccharide synthase activity. The two L. pneumophila lpxB paralogues are not functionally equivalent, since expression of lcsC/lpxB1 but not lpxB2 in an L. pneumophila icmG mutant is cytotoxic for A. castellanii, and LPS purified from the two strains triggers CD14-dependent tumour necrosis factor (TNF)alpha production by macrophages with a different potency. The lpxB and lpxA paralogues are expressed under various growth conditions, including broth, biofilms and in A. castellanii. While the flagellar gene flaA is mainly expressed in late stationary phase, the lpxB and lpxA paralogues are preferentially expressed in the exponential and early stationary phases. Upon exposure to hypotonic stress and nutrient deprivation, lpxA1, and to a lesser extent lcsC/lpxB1, is upregulated. The differential regulation of lpxB or lpxA paralogues in response to changing environmental conditions might allow L. pneumophila to adapt its lipid A structure.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
1350-0872
pubmed:author
pubmed:issnType
Print
pubmed:volume
153
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
3817-29
pubmed:meshHeading
pubmed:year
2007
pubmed:articleTitle
Expression of Legionella pneumophila paralogous lipid A biosynthesis genes under different growth conditions.
pubmed:affiliation
ETH Zürich, Institute of Microbiology, Wolfgang-Pauli Strasse 10, HCI G405, 8093 Zürich, Switzerland.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't