Linked Life Data

11532145

Source:http://linkedlifedata.com/resource/pubmed/id/11532145

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
2001-9-4
pubmed:abstractText
In the N2-fixing bacterium Rhizobium leguminosarum, mutations in a homologue of tonB (tonB(Rl)) block the import of vicibactin and haem as iron sources in free-living bacteria. TonB(Rl) mutants were normal for growth with ferric dicitrate and slightly reduced for growth with haemoglobin as sole iron sources. The deduced TonB(Rl) product is larger than that of (for example) Escherichia coli, on account of an extended N-terminal domain. Transcription of tonB(Rl) was enhanced in low-Fe growth conditions; this was not controlled by Fur, nor RpoI, an Fe-regulated extracytoplasmic sigma factor. Upstream of tonB(Rl) and transcribed divergently is an operon, hmuPSTUV, whose products are homologous to ABC transporters involved in haem uptake in pathogenic bacteria. Expression of hmuPSTUV was enhanced in low-Fe conditions, and hmu mutants show slightly diminished growth on haem as sole Fe source, suggesting that there is more than one system for the uptake of this molecule. hmuPSTUV expression appears to be from three closely linked promoters. Downstream of hmuPSTUV, a gene that may encode an extracytoplasmic sigma factor was identified, but this gene, rpoZ, did not affect the transcription of tonB(Rl) or hmuPSTUV. Mutations in tonB(Rl), hmu genes and rpoZ did not affect symbiotic N(2) fixation in peas.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0950-382X
pubmed:author
pubmed:issnType
Print
pubmed:volume
41
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
801-16
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed-meshheading:11532145-Bacterial Proteins, pubmed-meshheading:11532145-Base Sequence, pubmed-meshheading:11532145-Biological Transport, pubmed-meshheading:11532145-Cloning, Molecular, pubmed-meshheading:11532145-Escherichia coli Proteins, pubmed-meshheading:11532145-Gene Expression Regulation, Bacterial, pubmed-meshheading:11532145-Heme, pubmed-meshheading:11532145-Iron, pubmed-meshheading:11532145-Membrane Proteins, pubmed-meshheading:11532145-Molecular Sequence Data, pubmed-meshheading:11532145-Mutation, pubmed-meshheading:11532145-Nitrogen Fixation, pubmed-meshheading:11532145-Operon, pubmed-meshheading:11532145-Promoter Regions, Genetic, pubmed-meshheading:11532145-Rhizobium leguminosarum, pubmed-meshheading:11532145-Siderophores, pubmed-meshheading:11532145-Transcription, Genetic
pubmed:year
2001
pubmed:articleTitle
The Rhizobium leguminosarum tonB gene is required for the uptake of siderophore and haem as sources of iron.
pubmed:affiliation
School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't