Blocking of iron uptake from transferrin by antibodies against the transferrin binding proteins inNeisseria meningitidis

1996 ◽  
Vol 20 (3) ◽  
pp. 127-139 ◽  
Author(s):  
M Pintor
Keyword(s):  
Iron Uptake ◽  
Binding Proteins ◽  
Transferrin Binding Proteins

Transferrin-mediated iron acquisition by pathogenic Neisseria

2002 ◽  
Vol 30 (4) ◽  
pp. 705-707 ◽  
Author(s):  
R. W. Evans ◽  
J. S. Oakhill
Keyword(s):  
Bacterial Cell ◽  
Iron Uptake ◽  
Binding Proteins ◽  
Current Knowledge ◽  
Iron Acquisition ◽  
Direct Interaction ◽  
Acquisition System ◽  
Uptake System ◽  
Short Account ◽  
Transferrin Binding Proteins

The pathogenic Neisseria have a siderophore-independent iron-uptake system reliant on a direct interaction between the bacterial cell and transferrin. In the meningococcus this uptake system is dependent on two surface-exposed transferrin-binding proteins. This short account will review our current knowledge of the transferrin-mediated iron-acquisition system of pathogenic Neisseria.

scholarly journals Identification of TbpA Residues Required for Transferrin-Iron Utilization by Neisseria gonorrhoeae

2008 ◽  
Vol 76 (5) ◽  
pp. 1960-1969 ◽  
Author(s):  
Jennifer M. Noto ◽  
Cynthia Nau Cornelissen
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Iron Uptake ◽  
Binding Proteins ◽  
Iron Acquisition ◽  
Uptake System ◽  
Wild Type ◽  
Conserved Motif ◽  
Alanine Substitution ◽  
Transferrin Binding Proteins ◽  
Iron Utilization

ABSTRACT Neisseria gonorrhoeae requires iron for survival in the human host and therefore expresses high-affinity receptors for iron acquisition from host iron-binding proteins. The gonococcal transferrin-iron uptake system is composed of two transferrin binding proteins, TbpA and TbpB. TbpA is a TonB-dependent, outer membrane transporter critical for iron acquisition, while TbpB is a surface-exposed lipoprotein that increases the efficiency of iron uptake. The precise mechanism by which TbpA mediates iron acquisition has not been elucidated; however, the process is distinct from those of characterized siderophore transporters. Similar to these TonB-dependent transporters, TbpA is proposed to have two distinct domains, a β-barrel and a plug domain. We hypothesize that the TbpA plug coordinates iron and therefore potentially functions in multiple steps of transferrin-mediated iron acquisition. To test this hypothesis, we targeted a conserved motif within the TbpA plug domain and generated single, double, and triple alanine substitution mutants. Mutagenized TbpAs were expressed on the gonococcal cell surface and maintained wild-type transferrin binding affinity. Single alanine substitution mutants internalized iron at wild-type levels, while the double and triple mutants showed a significant decrease in iron uptake. Moreover, the triple alanine substitution mutant was unable to grow on transferrin as a sole iron source; however, expression of TbpB compensated for this defect. These data indicate that the conserved motif between residues 120 and 122 of the TbpA plug domain is critical for transferrin-iron utilization, suggesting that this region plays a role in iron acquisition that is shared by both TbpA and TbpB.

scholarly journals Transferrin Binding Proteins as a Means to Obtain Iron in Parasitic Protozoa

10.5772/48288 ◽  
2012 ◽  
Author(s):  
Magda Reyes-Lpez ◽  
Jess Serrano-Luna ◽  
Carolina Pia-Vzquez ◽  
Mireya de la Garz
Keyword(s):  
Binding Proteins ◽  
Parasitic Protozoa ◽  
Transferrin Binding Proteins

Methods for Manipulation of Transferrin-Binding Proteins

2003 ◽  
pp. 109-120 ◽  
Author(s):  
Leanne M. DeWinter ◽  
Anthony B. Schryvers
Keyword(s):  
Binding Proteins ◽  
Transferrin Binding Proteins

scholarly journals Identification of Discrete Domains within Gonococcal Transferrin-Binding Protein A That Are Necessary for Ligand Binding and Iron Uptake Functions

2000 ◽  
Vol 68 (12) ◽  
pp. 6988-6996 ◽  
Author(s):  
Ian C. Boulton ◽  
Mary Kate Yost ◽  
James E. Anderson ◽  
Cynthia Nau Cornelissen
Keyword(s):  
Ligand Binding ◽  
Iron Uptake ◽  
Binding Protein ◽  
Protein A ◽  
Ligand Interaction ◽  
Whole Cells ◽  
Affinity Ligand ◽  
Discrete Domains ◽  
Transferrin Binding Proteins

ABSTRACT The availability of free iron in vivo is strictly limited, in part by the iron-binding protein transferrin. The pathogenicNeisseria spp. can sequester iron from this protein, dependent upon two iron-repressible, transferrin-binding proteins (TbpA and TbpB). TbpA is a TonB-dependent, integral, outer membrane protein that may form a β-barrel exposing multiple surface loops, some of which are likely to contain ligand-binding motifs. In this study we propose a topological model of gonococcal TbpA and then test some of the hypotheses set forth by the model by individually deleting three putative loops (designated loops 4, 5, and 8). Each mutant TbpA could be expressed without toxicity and was surface exposed as assessed by immunoblotting, transferrin binding, and protease accessibility. Deletion of loop 4 or loop 5 abolished transferrin binding to whole cells in solid- and liquid-phase assays, while deletion of loop 8 decreased the affinity of the receptor for transferrin without affecting the copy number. Strains expressing any of the three mutated TbpAs were incapable of growth on transferrin as a sole iron source. These data implicate putative loops 4 and 5 as critical determinants for receptor function and transferrin-iron uptake by gonococcal TbpA. The phenotype of the ΔL8TbpA mutant suggests that high-affinity ligand interaction is required for transferrin-iron internalization.

scholarly journals Gonococcal Genes Encoding Transferrin-Binding Proteins A and B Are Arranged in a Bicistronic Operon but Are Subject to Differential Expression

2001 ◽  
Vol 69 (10) ◽  
pp. 6336-6347 ◽  
Author(s):  
Chalinee Ronpirin ◽  
Ann E. Jerse ◽  
Cynthia Nau Cornelissen
Keyword(s):  
Binding Proteins ◽  
Iron Acquisition ◽  
Sole Source ◽  
Mrna Levels ◽  
Rt Pcr ◽  
Upstream Promoter ◽  
Genes Encoding ◽  
Transferrin Binding Proteins ◽  
Iron Binding Proteins ◽  
Fusion Analysis

ABSTRACT Neisseria gonorrhoeae is capable of utilizing host iron-binding proteins, such as transferrin, lactoferrin, and hemoglobin, as the sole source of iron. The receptor involved in transferrin iron acquisition is composed of two distinct transferrin-binding proteins, TbpA and TbpB. The genes that encode these proteins are linked on the chromosome in the ordertbpB-tbpA but are separated by an inverted repeat of unknown function. In this study, we sought to understand the transcriptional organization and regulation of thetbp genes, using a combination of lacZtranscriptional fusion analysis and reverse transcriptase PCR (RT-PCR). First, we demonstrated that tbpB and tbpAare cotranscribed and coregulated from the common upstream promoter that precedes tbpB. Using β-galactosidase activity as a surrogate for tbp-specific transcription, we found that tbpB-specific transcripts were more prevalent thantbpA-specific transcripts after 2 h of growth under iron stress conditions. We confirmed the results obtained by fusion analysis by using RT-PCR applied to native RNA isolated from wild-type gonococci. Three different varieties of RT-PCR were employed: relative, competitive, and real time quantitative. The results of all analyses indicated that tbpB-specific transcripts were approximately twofold more prevalent than tbpA-specific transcripts at steady state. In iron-stressed cultures, the ratio oftbpB- to tbpA-specific message was approximately 2; however, in iron-replete cultures, this ratio dropped to 1. Using these techniques, we also quantitated the effects of iron, external pH, and presence of ligand on tbp mRNA levels.

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