scholarly journals Pumping iron: mechanisms for iron uptake by Campylobacter

Microbiology ◽  
2009 ◽  
Vol 155 (10) ◽  
pp. 3157-3165 ◽  
Author(s):  
Claire E. Miller ◽  
Peter H. Williams ◽  
Julian M. Ketley
Keyword(s):  
Outer Membrane ◽  
Molecular Characterization ◽  
Iron Uptake ◽  
Receptor Protein ◽  
Outer Membrane Receptor ◽  
Inner Membrane ◽  
Putative Receptor ◽  
Successful Colonization ◽  
Insight Into

Campylobacter requires iron for successful colonization of the host. In the last 7 years, a wealth of data has been generated allowing detailed molecular characterization of Campylobacter iron-uptake systems. Several exogenous siderophores have been identified as sources of ferric iron for Campylobacter. Ferri-enterochelin uptake requires both the outer-membrane receptor protein CfrA and the inner-membrane ABC transporter system CeuBCDE. Ferrichrome has been shown to support growth of some Campylobacter jejuni strains and the presence of homologues of Escherichia coli fhuABD genes was proposed; the Cj1658–Cj1663 system appears to be involved in the uptake of ferri-rhodotorulic acid. In addition to siderophores, the importance of host iron sources was highlighted by recent studies demonstrating that C. jejuni can exploit haem compounds and the transferrins using ChuABCDZ and Cj0173c–Cj0178, respectively. An additional putative receptor, Cj0444, present in some, but not all, strains has not yet been characterized. Following diffusion through the outer membrane, inner-membrane transport of ferrous iron can occur via the FeoB protein. While it may be assumed that all systems are not essential, there is growing evidence supporting the need for multiple iron-uptake systems for successful host colonization by Campylobacter. In light of this, comparative molecular characterization of iron systems in all Campylobacter strains is necessary to gain further insight into the pathogenesis of members of this genus.

The central matrix loop drives import of uncoupling protein 1 into mitochondria

2000 ◽  
Vol 113 (12) ◽  
pp. 2267-2272 ◽  
Author(s):  
E. Schleiff ◽  
H. McBride
Keyword(s):  
Outer Membrane ◽  
Uncoupling Protein ◽  
Full Length ◽  
Receptor Protein ◽  
Outer Membrane Receptor ◽  
Inner Mitochondrial Membrane ◽  
Inner Membrane ◽  
Amino Terminal ◽  
Repeated Unit ◽  
Targeting Signal

The uncoupling protein (UCP1) is a carrier protein of the inner mitochondrial membrane spanning the bilayer six times. It does not contain a typical amino-terminal targeting signal and the mechanism of targeting and insertion is unknown. Here we focus on the biogenesis of UCP1 by analysing the import signals contained within the three repeated units of the protein. The amino-terminal third of the protein can mediate insertion into the outer membrane and therefore acts as artificial targeting signal when fused to DHFR. However, in the context of full-length UCP, the targeting information contained within the first repeated unit is not sufficient to trigger insertion into the outer membrane. Deletion of either the first or third repeated unit from UCP1 did not reduce import into the inner membrane and bound to the outer membrane receptor protein hTom20 with the characteristics of full-length UCP1. Deletion of the second repeat of UCP1 completely abolished all import into the mitochondria. Consistent with this, the central repeat alone was efficiently imported to the inner membrane and bound hTom20 with the characteristics of UCP1. We conclude that the site for binding hTom20 is within the central repeat and that this domain contains the complete targeting signal for directing UCP1 to the inner membrane.

Characterization of the stability functions and inverted repeat structure X3 of the IncFI plasmid ColV2-K94

1986 ◽  
Vol 32 (10) ◽  
pp. 806-813
Author(s):  
Peter C. Weber ◽  
Sunil Palchaudhuri
Keyword(s):  
Outer Membrane ◽  
Inverted Repeat ◽  
Iron Uptake ◽  
Membrane Receptor ◽  
Outer Membrane Receptor ◽  
Plasmid Maintenance ◽  
Stability Functions ◽  
Repeat Structure ◽  
The Stability

A region of the IncFI plasmid ColV2-K94 which showed homology to the sop partitioning genes of F was cloned and characterized in an attempt to study the stability functions of this element. The sop region contained the incD incompatibility determinant common to many IncFI plasmids, but could not confer on ColV2-K94 miniplasmids the same stable inheritance found in the intact ColV2-K94; thus, other functions appear to be required for efficient plasmid maintenance. Adjacent to the area of sop homology was the X3 region, which was found to contain three inverted IS1-like sequences. The X3 region of ColV2-K94 was similar in organization to the aerobactin iron uptake region of ColV3-K30, but ColV2-K94 lacked the ability to synthesize either the aerobactin siderophore or its outer membrane receptor.

Characterization of the cloacin DF13/aerobactin outer membrane receptor protein of Escherichia coli (pFS8)

1985 ◽  
Vol 51 (5-6) ◽  
pp. 553-554
Author(s):  
Willy J. A. Krone ◽  
Freek Stegehuis ◽  
Frits K. de Graaf ◽  
Bauke Oudega
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Membrane Receptor ◽  
Receptor Protein ◽  
Outer Membrane Receptor

scholarly journals Pyoverdine-Mediated Iron Uptake in Pseudomonas aeruginosa: the Tat System Is Required for PvdN but Not for FpvA Transport

2006 ◽  
Vol 188 (9) ◽  
pp. 3317-3323 ◽  
Author(s):  
Romé Voulhoux ◽  
Alain Filloux ◽  
Isabelle J. Schalk
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Outer Membrane ◽  
Iron Uptake ◽  
Cytoplasmic Membrane ◽  
Signal Sequence ◽  
Iron Release ◽  
Outer Membrane Receptor ◽  
Uptake Pathway ◽  
Uptake Process ◽  
Tat System

ABSTRACT Under iron-limiting conditions, Pseudomonas aeruginosa PAO1 secretes a fluorescent siderophore called pyoverdine (Pvd). After chelating iron, this ferric siderophore is transported back into the cells via the outer membrane receptor FpvA. The Pvd-dependent iron uptake pathway requires several essential genes involved in both the synthesis of Pvd and the uptake of ferric Pvd inside the cell. A previous study describing the global phenotype of a tat-deficient P. aeruginosa strain showed that the defect in Pvd-mediated iron uptake was due to the Tat-dependent export of proteins involved in Pvd biogenesis and ferric Pvd uptake (U. Ochsner, A. Snyder, A. I. Vasil, and M. L. Vasil, Proc. Natl. Acad. Sci. USA 99:8312-8317, 2002). Using biochemical and biophysical tools, we showed that despite its predicted Tat signal sequence, FpvA is correctly located in the outer membrane of a tat mutant and is fully functional for all steps of the iron uptake process (ferric Pvd uptake and recycling of Pvd on FpvA after iron release). However, in the tat mutant, no Pvd was produced. This suggested that a key element in the Pvd biogenesis pathway must be exported to the periplasm by the Tat pathway. We located PvdN, a still unknown but essential component in Pvd biogenesis, at the periplasmic side of the cytoplasmic membrane and showed that its export is Tat dependent. Our results further support the idea that a critical step of the Pvd biogenesis pathway involving PvdN occurs at the periplasmic side of the cytoplasmic membrane.

scholarly journals Molecular characterization of an Enterobacter cloacae outer membrane protein (OmpX).

1991 ◽  
Vol 173 (1) ◽  
pp. 156-160 ◽  
Author(s):  
J Stoorvogel ◽  
M J van Bussel ◽  
J Tommassen ◽  
J A van de Klundert
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Molecular Characterization ◽  
Outer Membrane Protein ◽  
Enterobacter Cloacae
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