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Zinc piracy as a mechanism of Neisseria meningitidis for evasion of nutritional immunity.

Stork M, Grijpstra J, Bos MP, Mañas Torres C, Devos N, Poolman JT, Chazin WJ, Tommassen J - PLoS Pathog. (2013)

Bottom Line: Expression of CbpA enables N. meningitidis to survive and propagate in the presence of calprotectin and to use calprotectin as a zinc source.Besides CbpA, also the TonB protein, which couples energy of the proton gradient across the inner membrane to receptor-mediated transport across the outer membrane, is required for the process.Together, our results demonstrate that N. meningitidis is able to subvert an important defense mechanism of the human host and to utilize calprotectin to promote its growth.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, Utrecht, Netherlands.

ABSTRACT
The outer membrane of Gram-negative bacteria functions as a permeability barrier that protects these bacteria against harmful compounds in the environment. Most nutrients pass the outer membrane by passive diffusion via pore-forming proteins known as porins. However, diffusion can only satisfy the growth requirements if the extracellular concentration of the nutrients is high. In the vertebrate host, the sequestration of essential nutrient metals is an important defense mechanism that limits the growth of invading pathogens, a process known as "nutritional immunity." The acquisition of scarce nutrients from the environment is mediated by receptors in the outer membrane in an energy-requiring process. Most characterized receptors are involved in the acquisition of iron. In this study, we characterized a hitherto unknown receptor from Neisseria meningitidis, a causative agent of sepsis and meningitis. Expression of this receptor, designated CbpA, is induced when the bacteria are grown under zinc limitation. We demonstrate that CbpA functions as a receptor for calprotectin, a protein that is massively produced by neutrophils and other cells and that has been shown to limit bacterial growth by chelating Zn²⁺ and Mn²⁺ ions. Expression of CbpA enables N. meningitidis to survive and propagate in the presence of calprotectin and to use calprotectin as a zinc source. Besides CbpA, also the TonB protein, which couples energy of the proton gradient across the inner membrane to receptor-mediated transport across the outer membrane, is required for the process. CbpA was found to be expressed in all N. meningitidis strains examined, consistent with a vital role for the protein when the bacteria reside in the host. Together, our results demonstrate that N. meningitidis is able to subvert an important defense mechanism of the human host and to utilize calprotectin to promote its growth.

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Related in: MedlinePlus

CbpA synthesis in a variety of meningococcal isolates.Various meningococcal isolates from our laboratory collection were grown in RPMI medium either supplemented or not with 0.5 µM ZnSO4 as indicated. After overnight growth, whole cell lysates were analyzed by Western blotting using an antiserum directed against CbpA. Where available [47], serogroups and clonal lineages of the strains are indicated. -, the strain was typed by Multi-Locus Enzyme Electrophoresis but could not be assigned to a specific clone.
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ppat-1003733-g005: CbpA synthesis in a variety of meningococcal isolates.Various meningococcal isolates from our laboratory collection were grown in RPMI medium either supplemented or not with 0.5 µM ZnSO4 as indicated. After overnight growth, whole cell lysates were analyzed by Western blotting using an antiserum directed against CbpA. Where available [47], serogroups and clonal lineages of the strains are indicated. -, the strain was typed by Multi-Locus Enzyme Electrophoresis but could not be assigned to a specific clone.

Mentions: The expression of many cell-surface-exposed proteins in N. meningitidis is prone to phase variation due to slipped-strand mispairing at short nucleotide repeats [17]. Inspection of the nucleotide sequence of cbpA and its promoter region did not reveal evidence for the presence of such repeats. Furthermore, the cbpA gene was found in all available genome sequences of N. meningitidis strains and the encoded protein showed high sequence conservation (Figure S3). Most of the variation is located in a small region between amino-acid residues 270–294 (Figure S3), which likely corresponds to a cell-surface-exposed loop of the protein that one anticipates, would be prone to immune selection. To further evaluate the conservation of the expression of cbpA, a series of strains was grown in RPMI medium either supplemented or not with 0.5 µM ZnSO4. Western blot analysis of whole cell lysates showed that the protein is expressed in all strains examined and that its expression is regulated by zinc availability (Figure 5). The ubiquitous presence of CbpA in all strains examined and the lack of phase variation suggest a vital role for the protein when the bacteria reside in the host.


Zinc piracy as a mechanism of Neisseria meningitidis for evasion of nutritional immunity.

Stork M, Grijpstra J, Bos MP, Mañas Torres C, Devos N, Poolman JT, Chazin WJ, Tommassen J - PLoS Pathog. (2013)

CbpA synthesis in a variety of meningococcal isolates.Various meningococcal isolates from our laboratory collection were grown in RPMI medium either supplemented or not with 0.5 µM ZnSO4 as indicated. After overnight growth, whole cell lysates were analyzed by Western blotting using an antiserum directed against CbpA. Where available [47], serogroups and clonal lineages of the strains are indicated. -, the strain was typed by Multi-Locus Enzyme Electrophoresis but could not be assigned to a specific clone.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3814407&req=5

ppat-1003733-g005: CbpA synthesis in a variety of meningococcal isolates.Various meningococcal isolates from our laboratory collection were grown in RPMI medium either supplemented or not with 0.5 µM ZnSO4 as indicated. After overnight growth, whole cell lysates were analyzed by Western blotting using an antiserum directed against CbpA. Where available [47], serogroups and clonal lineages of the strains are indicated. -, the strain was typed by Multi-Locus Enzyme Electrophoresis but could not be assigned to a specific clone.
Mentions: The expression of many cell-surface-exposed proteins in N. meningitidis is prone to phase variation due to slipped-strand mispairing at short nucleotide repeats [17]. Inspection of the nucleotide sequence of cbpA and its promoter region did not reveal evidence for the presence of such repeats. Furthermore, the cbpA gene was found in all available genome sequences of N. meningitidis strains and the encoded protein showed high sequence conservation (Figure S3). Most of the variation is located in a small region between amino-acid residues 270–294 (Figure S3), which likely corresponds to a cell-surface-exposed loop of the protein that one anticipates, would be prone to immune selection. To further evaluate the conservation of the expression of cbpA, a series of strains was grown in RPMI medium either supplemented or not with 0.5 µM ZnSO4. Western blot analysis of whole cell lysates showed that the protein is expressed in all strains examined and that its expression is regulated by zinc availability (Figure 5). The ubiquitous presence of CbpA in all strains examined and the lack of phase variation suggest a vital role for the protein when the bacteria reside in the host.

Bottom Line: Expression of CbpA enables N. meningitidis to survive and propagate in the presence of calprotectin and to use calprotectin as a zinc source.Besides CbpA, also the TonB protein, which couples energy of the proton gradient across the inner membrane to receptor-mediated transport across the outer membrane, is required for the process.Together, our results demonstrate that N. meningitidis is able to subvert an important defense mechanism of the human host and to utilize calprotectin to promote its growth.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, Utrecht, Netherlands.

ABSTRACT
The outer membrane of Gram-negative bacteria functions as a permeability barrier that protects these bacteria against harmful compounds in the environment. Most nutrients pass the outer membrane by passive diffusion via pore-forming proteins known as porins. However, diffusion can only satisfy the growth requirements if the extracellular concentration of the nutrients is high. In the vertebrate host, the sequestration of essential nutrient metals is an important defense mechanism that limits the growth of invading pathogens, a process known as "nutritional immunity." The acquisition of scarce nutrients from the environment is mediated by receptors in the outer membrane in an energy-requiring process. Most characterized receptors are involved in the acquisition of iron. In this study, we characterized a hitherto unknown receptor from Neisseria meningitidis, a causative agent of sepsis and meningitis. Expression of this receptor, designated CbpA, is induced when the bacteria are grown under zinc limitation. We demonstrate that CbpA functions as a receptor for calprotectin, a protein that is massively produced by neutrophils and other cells and that has been shown to limit bacterial growth by chelating Zn²⁺ and Mn²⁺ ions. Expression of CbpA enables N. meningitidis to survive and propagate in the presence of calprotectin and to use calprotectin as a zinc source. Besides CbpA, also the TonB protein, which couples energy of the proton gradient across the inner membrane to receptor-mediated transport across the outer membrane, is required for the process. CbpA was found to be expressed in all N. meningitidis strains examined, consistent with a vital role for the protein when the bacteria reside in the host. Together, our results demonstrate that N. meningitidis is able to subvert an important defense mechanism of the human host and to utilize calprotectin to promote its growth.

Show MeSH
Related in: MedlinePlus