Limits...
Aquaporins with anion/monocarboxylate permeability: mechanisms, relevance for pathogen-host interactions.

Rambow J, Wu B, Rönfeldt D, Beitz E - Front Pharmacol (2014)

Bottom Line: It became apparent that not all aquaporins clearly fit into one of only two subfamilies.Here, we summarize the findings on aquaporin anion transport, analyze the pore layout of such aquaporins in comparison to prototypical non-selective anion channels, monocarboxylate transporters, and formate-nitrite transporters.Finally, we discuss in which scenarios anion conducting aquaporins may be of physiological relevance.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmaceutical and Medicinal Chemistry, Christian-Albrechts-University of Kiel Kiel, Germany.

ABSTRACT
Classically, aquaporins are divided based on pore selectivity into water specific, orthodox aquaporins and solute-facilitating aquaglyceroporins, which conduct, e.g., glycerol and urea. However, more aquaporin-passing substrates have been identified over the years, such as the gasses ammonia and carbon dioxide or the water-related hydrogen peroxide. It became apparent that not all aquaporins clearly fit into one of only two subfamilies. Furthermore, certain aquaporins from both major subfamilies have been reported to conduct inorganic anions, such as chloride, or monoacids/monocarboxylates, such as lactic acid/lactate. Here, we summarize the findings on aquaporin anion transport, analyze the pore layout of such aquaporins in comparison to prototypical non-selective anion channels, monocarboxylate transporters, and formate-nitrite transporters. Finally, we discuss in which scenarios anion conducting aquaporins may be of physiological relevance.

No MeSH data available.


Related in: MedlinePlus

Chemical protonation equilibrium of weak monoacids. The curves indicate the fraction of the protonated, neutral forms of acetic, lactic, and pyruvic acid in a pH range from 0 to 8. Calculations were done using the Hendersen–Hasselbalch equation; pKa values are given at the molecule structures.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4150397&req=5

Figure 3: Chemical protonation equilibrium of weak monoacids. The curves indicate the fraction of the protonated, neutral forms of acetic, lactic, and pyruvic acid in a pH range from 0 to 8. Calculations were done using the Hendersen–Hasselbalch equation; pKa values are given at the molecule structures.

Mentions: Besides inorganic anions, a physiological environment contains organic metabolites with negative charges in the form of carboxylates, such as acetate, pyruvate, or lactate. Here, the situation is complicated by the pH-dependent chemical protonation equilibrium, which renders the compounds anionic in the neutral and alkaline range and uncharged in the acidic range (Figure 3). Several reports have suggested permeability of certain AQPs for monocarboxylates (Tsukaguchi et al., 1998; Choi and Roberts, 2007; Faghiri et al., 2010; Bienert et al., 2013).


Aquaporins with anion/monocarboxylate permeability: mechanisms, relevance for pathogen-host interactions.

Rambow J, Wu B, Rönfeldt D, Beitz E - Front Pharmacol (2014)

Chemical protonation equilibrium of weak monoacids. The curves indicate the fraction of the protonated, neutral forms of acetic, lactic, and pyruvic acid in a pH range from 0 to 8. Calculations were done using the Hendersen–Hasselbalch equation; pKa values are given at the molecule structures.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4150397&req=5

Figure 3: Chemical protonation equilibrium of weak monoacids. The curves indicate the fraction of the protonated, neutral forms of acetic, lactic, and pyruvic acid in a pH range from 0 to 8. Calculations were done using the Hendersen–Hasselbalch equation; pKa values are given at the molecule structures.
Mentions: Besides inorganic anions, a physiological environment contains organic metabolites with negative charges in the form of carboxylates, such as acetate, pyruvate, or lactate. Here, the situation is complicated by the pH-dependent chemical protonation equilibrium, which renders the compounds anionic in the neutral and alkaline range and uncharged in the acidic range (Figure 3). Several reports have suggested permeability of certain AQPs for monocarboxylates (Tsukaguchi et al., 1998; Choi and Roberts, 2007; Faghiri et al., 2010; Bienert et al., 2013).

Bottom Line: It became apparent that not all aquaporins clearly fit into one of only two subfamilies.Here, we summarize the findings on aquaporin anion transport, analyze the pore layout of such aquaporins in comparison to prototypical non-selective anion channels, monocarboxylate transporters, and formate-nitrite transporters.Finally, we discuss in which scenarios anion conducting aquaporins may be of physiological relevance.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmaceutical and Medicinal Chemistry, Christian-Albrechts-University of Kiel Kiel, Germany.

ABSTRACT
Classically, aquaporins are divided based on pore selectivity into water specific, orthodox aquaporins and solute-facilitating aquaglyceroporins, which conduct, e.g., glycerol and urea. However, more aquaporin-passing substrates have been identified over the years, such as the gasses ammonia and carbon dioxide or the water-related hydrogen peroxide. It became apparent that not all aquaporins clearly fit into one of only two subfamilies. Furthermore, certain aquaporins from both major subfamilies have been reported to conduct inorganic anions, such as chloride, or monoacids/monocarboxylates, such as lactic acid/lactate. Here, we summarize the findings on aquaporin anion transport, analyze the pore layout of such aquaporins in comparison to prototypical non-selective anion channels, monocarboxylate transporters, and formate-nitrite transporters. Finally, we discuss in which scenarios anion conducting aquaporins may be of physiological relevance.

No MeSH data available.


Related in: MedlinePlus