The Nramp Homologue Encoded by Mycobacterium Tuberculosis is a Ph-Dependent Divalent Cation Transporter

1999 ◽  
Vol 97 (s41) ◽  
pp. 10P-11P
Author(s):  
D. Agranoff ◽  
I. Monahan ◽  
J. Mangan ◽  
P. Butcher ◽  
S. Krishna
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Divalent Cation ◽  
Ph Dependent ◽  
Divalent Cation Transporter

GENE ORGANIZATION AND EXPRESSION OF THE DIVALENT CATION TRANSPORTER NRAMP IN THE PROTISTAN PARASITE PERKINSUS MARINUS

2004 ◽  
Vol 90 (5) ◽  
pp. 1004-1014 ◽  
Author(s):  
José-Antonio F. Robledo ◽  
Pascal Courville ◽  
Mathieu F. M. Cellier ◽  
Gerardo R. Vasta
Keyword(s):  
Divalent Cation ◽  
Gene Organization ◽  
Perkinsus Marinus ◽  
Divalent Cation Transporter

scholarly journals pH-dependent pore-forming activity of OmpATb from Mycobacterium tuberculosis and characterization of the channel by peptidic dissection

2006 ◽  
Vol 61 (3) ◽  
pp. 826-837 ◽  
Author(s):  
Virginie Molle ◽  
Nathalie Saint ◽  
Sylvie Campagna ◽  
Laurent Kremer ◽  
Edward Lea ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Ph Dependent

scholarly journals The regulation of mineral absorption in the gastrointestinal tract

1999 ◽  
Vol 58 (1) ◽  
pp. 147-153 ◽  
Author(s):  
J. J. Powell ◽  
R. Jugdaohsingh ◽  
R. P. H. Thompson
Keyword(s):  
Metal Ions ◽  
Divalent Cation ◽  
Metal Binding ◽  
Metal Ion ◽  
Divalent Cations ◽  
Transmembrane Protein ◽  
Mineral Absorption ◽  
Basolateral Side ◽  
Molecule Transport ◽  
Divalent Cation Transporter

The absorption of metal ions in the mammalian single-stomached gut is fortunately highly selective, and both luminal and tissue regulation occur. Initially, assimilation of metal ions in an available form is facilitated by the intestinal secretions, chiefly soluble mucus (mucin) that retards hydrolysis of ions such as Cu, Fe and Zn. Metal ions then bind and traverse the mucosally-adherent mucus layer with an efficiency M+> M2+> M3+. At the mucosa Fe3+is probably uniquely reduced to Fe2+, and all divalent cations (including Fe2+) are transported by a membrane protein (such as divalent cation transporter 1) into the cell. This minimizes absorption of toxic trivalent metals (e.g. A13+). Intracellular metal-binding molecules (such as mobilferrin) may be present at the intracellular side of the apical membrane, anchored to a transmembrane protein such as an integrin complex. This mobilferrin would receive the metal ion from divalent cation transporter 1 and, with part of the integrin molecule, transport the metal to the cytosol for safe sequestration in a larger complex such as ferritin or‘paraferritin’. β2-Microglobulin and HFE (previously termed human leucocyte antigen H) may be involved in stabilizing metal mobilferrin-integrin to form this latter complex. Finally, a systemic metal-binding protein such as transferrin may enter the antiluminal (basolateral) side of the cell for binding of the sequestered metal ion and delivery to the circulation. Regulatory proteins, such as HFE, may determine the degree of ion transport from intestinal cells to the circulation. Gradients in pH and perhaps pCa or even pNa could allow the switching of ions between the different transporters throughout this mechanism.

scholarly journals Evolution of Differences in Transport Function in Slc11a Family Members

2007 ◽  
Vol 282 (49) ◽  
pp. 35646-35656 ◽  
Author(s):  
Michala Eichner Techau ◽  
Javier Valdez-Taubas ◽  
Jean-François Popoff ◽  
Richard Francis ◽  
Matthew Seaman ◽  
...  
Keyword(s):  
Divalent Cation ◽  
Mammalian Cells ◽  
Transmembrane Domain ◽  
Divalent Cations ◽  
Transport Function ◽  
Cation Uptake ◽  
Cation Homeostasis ◽  
N Terminus ◽  
Resistance To Infection ◽  
Divalent Cation Transporter

Slc11a1 (formerly Nramp1) is a proton/divalent cation transporter that regulates cation homeostasis in macrophages. Slc11a2 mediates divalent cation uptake via the gut and delivery into cells. The mode of action of the two transporters remains controversial. Heterologous expression in frog oocytes shows Slc11a2 is a symporter, whereas Slc11a1 is an antiporter fluxing divalent cations against the proton gradient. This explains why Slc11a2, but not Slc11a1, can complement EGTA sensitivity in smf1Δ/smf2Δ/smf3Δ yeast. However, some studies of transport in mammalian cells suggest Slc11a1 is a symporter. We now demonstrate that Slc11a1, but not Slc11a2, complements a divalent cation stress phenotype in bsd2Δ/rer1Δ yeast. This is the first description of a yeast complementation assay for Slc11a1 function. Given the prior demonstration in frog oocytes that Slc11a1 acts as an antiporter, the most plausible interpretation of the data is that Slc11a1 is rescuing bsd2Δ/rer1Δ yeast by exporting divalent cations. Chimaeras define the N terminus, and a segment of the protein core preceding transmembrane domain 9 through transmembrane domain 12, as important in rescuing the divalent cation stress phenotype. EGTA sensitivity and divalent cation stress phenotypes in yeast expressing Slc11a orthologues show that symport activity is ancestral. Molecular changes that mediate rescue of the divalent cation stress phenotype post-date frogs and co-evolved with Slc11a1 orthologues that regulate divalent cation homeostasis in macrophages and resistance to infection in chickens and mammals.

Roles of Divalent-Cation Transporter Genes mntB and mntC of Beer Spoilage Bacteria in Resisting Hop Bitter Compound Iso-α-Acid

2020 ◽  
Vol 79 (1) ◽  
pp. 90-98
Author(s):  
Feiyun Zheng ◽  
Tianmu Wang ◽  
Chengtuo Niu ◽  
Ruilong Zheng ◽  
Chunfeng Liu ◽  
...  
Keyword(s):  
Divalent Cation ◽  
Bitter Compound ◽  
Spoilage Bacteria ◽  
Beer Spoilage ◽  
Divalent Cation Transporter

scholarly journals Genetic and metabolic regulation ofMycobacterium tuberculosisacid growth arrest

2017 ◽  
Author(s):  
Jacob J. Baker ◽  
Robert B. Abramovitch
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Metabolic Regulation ◽  
Isocitrate Lyase ◽  
Growth Arrest ◽  
Drug Tolerance ◽  
Acidic Ph ◽  
Acid Growth ◽  
Physiological Basis ◽  
Acidic Environments ◽  
Ph Dependent

AbstractMycobacterium tuberculosis(Mtb) senses and adapts to acidic environments during the course of infection. Acidic pH-dependent adaptations include the induction of metabolic genes associated with anaplerosis and growth arrest on specific carbon sources. In this study, reverse and forward genetic studies were undertaken to define new mechanisms underlying pH-dependent adaptations. Here we report that deletion of isocitrate lyase (icl1/2) or phosphoenolpyruvate carboxykinase (pckA) results in reduced growth at acidic pH and altered metabolite profiles, supporting that remodeling of anaplerotic metabolism is required for pH-dependent adaptation. Mtb cultured at pH 5.7 in minimal medium containing glycerol as a single carbon source exhibits an acid growth arrest phenotype, where the bacterium is non-replicating but viable and metabolically active. The bacterium uptakes and metabolizes glycerol and maintains ATP pools during acid growth arrest and becomes tolerant to detergent stress and the antibiotics isoniazid and rifampin. A forward genetic screen identified mutants that do not arrest their growth at acidic pH, including four enhanced acid growth (eag) mutants with three distinct mutations in the PPE gene MT3221. Overexpression of the MT3221(S211R) variant protein in wild type Mtb results in enhanced acid growth and reduced drug tolerance. Together, these findings provide new evidence for a genetic and physiological basis for acid growth arrest and support that growth arrest is an adaptive process and not simply a physiological limitation associated with acidic pH.Author SummaryThe bacteriumMycobacterium tuberculosis(Mtb) causes the disease tuberculosis in humans. During infection Mtb colonizes a variety of environments that have acidic environments and Mtb must adapt to these environments to cause disease. One of these adaptations is that Mtb slows and arrests its growth at acidic pH, and the goal of this study was to examine the genetics and physiology of these pH-dependent adaptations. We found that Mtb modifies its metabolism at acidic pH and that these adaptations are required for optimal growth. We also found that acidic pH and specific nutrient sources can promote the bacterium to enter a state of dormancy, called acid growth arrest, where the bacterium becomes tolerant to antibiotics. Mutants were identified that do not arrest their growth at acidic, revealing that acid growth arrest is a genetically controlled process. Overall, understanding how Mtb adapts to acidic pH has revealed pathway that are required for virulence and drug tolerance and thus may identify new targets for drug development that may function to shorten the course of TB therapy.

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