Search PubMed⌕ Search
Home/Archive/PubMed

PubMed · 11872826

Close before opening.

K Postle
View original source ↗Export metadata ↓

Abstract

As bacteria need iron from the environment to survive, they have evolved active iron transporter proteins in their outer membranes. In her Perspective, Postle discusses new insights into iron transport revealed by the crystal structure of the iron transporter FecA in E. coli (Ferguson et al.).

Explore related subjects

Bacterial Outer Membrane ProteinsBacterial ProteinsBinding SitesBiological Transport, ActiveCarrier ProteinsCell MembraneCrystallography, X-RayEscherichia coliEscherichia coli ProteinsFerric CompoundsIon Channel GatingLigandsMembrane ProteinsModels, BiologicalProtein BindingProtein ConformationProtein Structure, TertiaryReceptors, Cell SurfaceSiderophoresJournal ArticleComment

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

K Postle. 2002-03-01. Close before opening.. https://doi.org/10.1126/science.1070129

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2025

TamL is a Key Player of the Outer Membrane Homeostasis in Bacteroidota.

In Proteobacteria, the outer membrane protein TamA and the inner membrane-anchored protein TamB form the Translocation and Assembly Module (TAM) complex, which facilitates the transport of autotransporters, virulence factors, and likely lipids across the two membranes. In Bacteroidota, TamA is replaced by TamL, a TamA-like lipoprotein with a lipid modification at its N-terminus that likely anchors it to the outer membrane. This structural difference suggests that TamL may have a distinct function compared to TamA. However, the role of TAM in bacterial phyla other than Proteobacteria remains unexplored. Our study aimed to elucidate the function of TamL in Flavobacterium johnsoniae, an environmental Bacteroidota. Unlike its homologs in Proteobacteria, we found that TamL and TamB are essential in F. johnsoniae. Through genetic, phenotypic, proteomic, and lipidomic analyses, we show that TamL depletion severely compromises outer membrane integrity, as evidenced by reduced cell viability, altered cell shape, increased susceptibility to membrane-disrupting agents, and elevated levels of outer membrane lipoproteins. Notably, we did not observe an overall decrease in the levels of β-barrel outer membrane proteins, nor substantial alterations in outer membrane lipid composition. By pull-down assays, we found TamL co-purifying with TamB in F. johnsoniae, suggesting an interaction. Furthermore, we found that while TamL and TamB monocistronic genes are conserved among Bacteroidota, only some species encode multiple TamL, TamB and TamA proteins. To our knowledge, this study is the first to provide functional insights into a TAM subunit beyond Proteobacteria.

Bacterial Outer Membrane Proteins↗
PubMed2003

Role of SeqA and Dam in Escherichia coli gene expression: a global/microarray analysis.

High-density oligonucleotide arrays were used to monitor global transcription patterns in Escherichia coli with various levels of Dam and SeqA proteins. Cells lacking Dam methyltransferase showed a modest increase in transcription of the genes belonging to the SOS regulon. Bacteria devoid of the SeqA protein, which preferentially binds hemimethylated DNA, were found to have a transcriptional profile almost identical to WT bacteria overexpressing Dam methyltransferase. The latter two strains differed from WT in two ways. First, the origin proximal genes were transcribed with increased frequency due to increased gene dosage. Second, chromosomal domains of high transcriptional activity alternate with regions of low activity, and our results indicate that the activity in each domain is modulated in the same way by SeqA deficiency or Dam overproduction. We suggest that the methylation status of the cell is an important factor in forming and/or maintaining chromosome structure.

Bacterial Outer Membrane Proteins↗
PubMed2003

Secretins of Pseudomonas aeruginosa: large holes in the outer membrane.

Pseudomonas aeruginosa produces a large number of exoproteins, ranging from the ADP-ribosyltransferases exotoxin A and ExoS to degradative enzymes, such as elastase and chitinase. As it is a gram-negative bacterium, P. aeruginosa must be able to transport these exoproteins across both membranes of the cell envelope. In addition, also proteins that are part of cellular appendages, such as type IV pili and flagella, have to cross the cell envelope. Whereas the majority of the proteins transported across the inner membrane are dependent on the Sec channel, the systems for translocation across the outer membrane seem to be more diverse. Gram-negative bacteria have invented a number of different strategies during the course of evolution to achieve this goal. Although these transport machineries seem to be radically different, many of them actually depend on a member of the secretin protein family for their function. Recent results show that secretins form a large complex in the outer membrane, which constitutes the actual translocation channel. Understanding the working mechanism of this protein translocation channel could open up new strategies to target molecular machineries at the heart of many important virulence factors.

Bacterial Outer Membrane Proteins↗