scholarly journals Iron Uptake Mechanisms in the Fish Pathogen Tenacibaculum maritimum

2005 ◽  
Vol 71 (11) ◽  
pp. 6947-6953 ◽  
Author(s):  
Ruben Avendaño-Herrera ◽  
Alicia E. Toranzo ◽  
Jesús L. Romalde ◽  
Manuel L. Lemos ◽  
Beatriz Magariños
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Iron Uptake ◽  
Outer Membrane Proteins ◽  
Chelating Agent ◽  
Proteinase K ◽  
Fish Pathogen ◽  
Whole Cells ◽  
Iron Deficient ◽  
Uptake Mechanisms

ABSTRACT We present here the first evidence of the presence of iron uptake mechanisms in the bacterial fish pathogen Tenacibaculum maritimum. Representative strains of this species, with different serotypes and origins, were examined. All of them were able to grow in the presence of the chelating agent ethylenediamine-di- (o-hydroxyphenyl acetic acid) (EDDHA) and also produced siderophores. Cross-feeding assays suggest that the siderophores produced are closely related. In addition, all T. maritimum strains utilized transferrin, hemin, hemoglobin, and ferric ammonic citrate as iron sources when added to iron-deficient media. Whole cells of all T. maritimum strains, grown under iron-supplemented or iron-restricted conditions, were able to bind hemin, indicating the existence of constitutive binding components located at the T. maritimum cell surface. This was confirmed by the observation that isolated total and outer membrane proteins from all of the strains, regardless of the iron levels of the media, were able to bind hemin, with the outer membranes showing the strongest binding. proteinase K treatment of whole cells did not affect the hemin binding, indicating that, in addition to proteins, some protease-resistant components could also bind hemin. At least three outer membrane proteins were induced in iron-limiting conditions, and all strains, regardless of their serotype, showed a similar pattern of induced proteins. The results of the present study suggest that T. maritimum possesses at least two different systems of iron acquisition: one involving the synthesis of siderophores and another that allows the utilization of heme groups as iron sources by direct binding.

scholarly journals Surface Immunolabeling and Consensus Computational Framework To Identify Candidate Rare Outer Membrane Proteins of Treponema pallidum

2010 ◽  
Vol 78 (12) ◽  
pp. 5178-5194 ◽  
Author(s):  
David L. Cox ◽  
Amit Luthra ◽  
Star Dunham-Ems ◽  
Daniel C. Desrosiers ◽  
Juan C. Salazar ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Treponema Pallidum ◽  
Immunoblot Analysis ◽  
Proteinase K ◽  
Membrane Proteome ◽  
Computational Framework ◽  
Shifting Balance ◽  
Dual Label

ABSTRACT Treponema pallidum reacts poorly with the antibodies present in rabbit and human syphilitic sera, a property attributed to the paucity of proteins in its outer membrane. To better understand the basis for the syphilis spirochete's “stealth pathogenicity,” we used a dual-label, 3-step amplified assay in which treponemes encapsulated in gel microdroplets were probed with syphilitic sera in parallel with anti-FlaA antibodies. A small (approximately 5 to 10%) but reproducible fraction of intact treponemes bound IgG and/or IgM antibodies. Three lines of evidence supported the notion that the surface antigens were likely β-barrel-forming outer membrane proteins (OMPs): (i) surface labeling with anti-lipoidal (VDRL) antibodies was not observed, (ii) immunoblot analysis confirmed prior results showing that T. pallidum glycolipids are not immunoreactive, and (iii) labeling of intact organisms was not appreciably affected by proteinase K (PK) treatment. With this method, we also demonstrate that TprK (TP0897), an extensively studied candidate OMP, and TP0136, a lipoprotein recently reported to be surface exposed, are both periplasmic. Consistent with the immunolabeling studies, TprK was also found to lack amphiphilicity, a characteristic property of β-barrel-forming proteins. Using a consensus computational framework that combined subcellular localization and β-barrel structural prediction tools, we generated ranked groups of candidate rare OMPs, the predicted T. pallidum outer membrane proteome (OMPeome), which we postulate includes the surface-exposed molecules detected by our enhanced gel microdroplet assay. In addition to underscoring the syphilis spirochete's remarkably poor surface antigenicity, our findings help to explain the complex and shifting balance between pathogen and host defenses that characterizes syphilitic infection.

Outer membrane proteins of Bacteroides fragilis and Bacteroides vulgatus in relation to iron uptake and virulence

1988 ◽  
Vol 4 (4) ◽  
pp. 279-287 ◽  
Author(s):  
B.R. Otto ◽  
A.M.J.J. Verweij-van Vught ◽  
J. van Doorn ◽  
D.M. Maclaren
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Iron Uptake ◽  
Outer Membrane Proteins ◽  
Bacteroides Fragilis

Studies on iron uptake and its effect on the outer membrane proteins ofPseudomonas stuzeri RC-7

1994 ◽  
Vol 28 (6) ◽  
pp. 321-323 ◽  
Author(s):  
R. N. Chakraborty ◽  
H. N. Patel ◽  
S. B. Desai
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Iron Uptake ◽  
Outer Membrane Proteins

Growth characteristics and expression of iron-regulated outer-membrane proteins of chemostat-grown biofilm cells of Pseudomonas aeruginosa

1991 ◽  
Vol 37 (10) ◽  
pp. 737-743 ◽  
Author(s):  
H. Anwar ◽  
J. L. Strap ◽  
J. W. Costerton
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Membrane Proteins ◽  
Dilution Rate ◽  
Outer Membrane ◽  
Iron Uptake ◽  
Iron Acquisition ◽  
Outer Membrane Proteins ◽  
Uptake System ◽  
Planktonic Cells

An in vitro chemostat system was used to study the growth and the expression of iron-regulated outer-membrane proteins (IROMPs) by biofilm cells of Pseudomonas aeruginosa cultivated under conditions of iron limitation. The population of the planktonic cells decreased when the dilution rate was increased. At a dilution rate of 0.05 h−1 the populations of planktonic cells of both mucoid and nonmucoid P. aeruginosa were 3 × 109 cells/mL. This value dropped to 5 × 106 cells/mL when the dilution rate was increased to 1.0 h−1. The reverse was observed for the biofilm cells. The number of biofilm cells colonising the silicone tubing increased when the dilution rate was increased. The number of biofilm cells of the mucoid strain at steady state was 2 × 108 cells/cm (length) when the dilution rate was fixed at 0.05 h−1. The figure increased to 8 × 109 cells/cm when the dilution rate was increased to 1.0 h−1. The population of biofilm cells of the nonmucoid strain was 9 × 107 cells/cm (length) when the dilution rate was 0.05 h−1. It increased to 2 × 109 cells/cm when the dilution rate was set at 1.0 h−1. The expression of IROMPs was induced in the biofilm cells of both mucoid and nonmucoid strains when the dilution rates were 0.05 and 0.2 h−1. IROMPs were reduced but still detectable at the dilution rate of 0.5 h−1. However, the expression of IROMPs was repressed when the dilution rate was increased to 1.0 h−1. The data suggest that the biofilm cells of P. aeruginosa switch on the expression of IROMPs to assist iron acquisition when the dilution rate used for the chemostat run is below 0.5 h−1. The high affinity iron uptake system is not required by the biofilm cells when the dilution rate is increased because the trace amount of iron present in the chemostat is sufficient for the growth of adherent biofilm cells. Key words: Pseudomonas aeruginosa, chemostat, iron, outer-membrane proteins, biofilm.

Serum antibodies in mares and foals to Actinobacillus equuli whole cells, outer membrane proteins, and Aqx toxin

2007 ◽  
Vol 118 (3-4) ◽  
pp. 310-316 ◽  
Author(s):  
G.R. Holyoak ◽  
C.M. Smith ◽  
R. Boyette ◽  
M. Montelongo ◽  
J.H. Wray ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Serum Antibodies ◽  
Whole Cells

scholarly journals Assembly of TolC, a Structurally Unique and Multifunctional Outer Membrane Protein of Escherichia coli K-12

2003 ◽  
Vol 185 (22) ◽  
pp. 6540-6547 ◽  
Author(s):  
John Werner ◽  
Anne Marie Augustus ◽  
Rajeev Misra
Keyword(s):  
Escherichia Coli ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Outer Membrane Proteins ◽  
The Other ◽  
Proteinase K ◽  
Folded Structure ◽  
K 12

ABSTRACT TolC is a multifunctional outer membrane protein of Escherichia coli that folds into a novel α-β-barrel conformation absent in the other model outer membrane proteins used in assembly studies. The data presented in this work show that the unique folded structure of TolC reflects a unique assembly pathway. During its assembly, the newly translocated nascent TolC monomers are released in the periplasm. Maturation of these nascent monomers, and possibly their oligomerization, in the periplasm precedes their insertion in the outer membrane. The completion of the assembly process is signaled by the development of a characteristic proteinase K-resistant fragment generated by cleavage at a single, periplasmically exposed, protease-sensitive site of the membrane-anchored trimer. None of the assembly steps of TolC is affected by known folding factors, such as SurA, Skp, and lipopolysaccharide, which have profound effects on the assembly of other model trimeric outer membrane proteins. Two assembly-defective TolC mutants were isolated and characterized. One of the mutants (TolCI106N) was defective in the folding of nascent monomers, while the other (TolCS350F) was impaired in steps involving trimerization and membrane insertion of folded monomers.

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