A novel aquaporin Aagp contributes to Streptococcus suis H2O2 efflux and virulence.

Streptococcus suis is a bacterium that can cause infections in pigs and humans. Although oxidative stress is common occurrence during bacterial growth and infection, the regulation networks of S. suis under oxidative stress remain poorly understood. To address this, we utilized RNA-Seq to reveal the transcriptional landscape of S. suis in response to H2O2 stress. We identified novel genes responsible for S. suis resistance to oxidative stress, including those involved in DNA repair or protection, and essential for the biosynthesis of amino acids and nucleic acids. In addition, we found that a novel aquaporin, Aagp, belonging to atypical aquaglyceroporins and widely distributed in diverse S. suis serotypes, plays a crucial role during H2O2 stress. By performing oxidative stress assays and measuring the intracellular H2O2 concentrations of the wild-type strain and Aagp mutants during H2O2 stress, we found that Aagp facilitated H2O2 efflux. Additionally, we found that Aagp might be involved in glycerol transport, as shown by the growth inhibition and H2O2 production in the presence of glycerol. Mice infection experiments indicated that Aagp contributed to S. suis virulence. This study contributes to understanding the mechanism of S. suis oxidative stress response, S. suis pathogenesis, and the function of aquaporins in prokaryotes.

Mechanisms of irreversible aquaporin-10 inhibition by organogold compounds studied by combined biophysical methods and atomistic simulations.

The inhibition of glycerol permeation via human aquaporin-10 (hAQP10) by organometallic gold complexes has been studied by stopped-flow fluorescence spectroscopy, and its mechanism has been described using molecular modelling and atomistic simulations. The most effective hAQP10 inhibitors are cyclometalated Au(III) C^N compounds known to efficiently react with cysteine residues leading to the formation of irreversible C-S bonds. Functional assays also demonstrate the irreversibility of the binding to hAQP10 by the organometallic complexes. The obtained computational results by metadynamics show that the local arylation of Cys209 in hAQP10 by one of the gold inhibitors is mapped into a global change of the overall free energy of glycerol translocation across the channel. Our study further pinpoints the need to understand the mechanism of glycerol and small molecule permeation as a combination of local structural motifs and global pore conformational changes, which are taking place on the scale of the translocation process and whose study, therefore, require sophisticated molecular dynamics strategies.

High-affinity transport, cyanide-resistant respiration, and ethanol production under aerobiosis underlying efficient high glycerol consumption by Wickerhamomyces anomalus.

Wickerhamomyces anomalus strain LBCM1105 was originally isolated from the wort of cachaça (the Brazilian fermented sugarcane juice-derived Brazilian spirit) and has been shown to grow exceptionally well at high amounts of glycerol. This paramount residue from the biodiesel industry is a promising cheap carbon source for yeast biotechnology. The assessment of the physiological traits underlying the W. anomalus glycerol consumption ability in opposition to Saccharomyces cerevisiae is presented. A new WaStl1 concentrative glycerol-H+ symporter with twice the affinity of S. cerevisiae was identified. As in this yeast, WaSTL1 is repressed by glucose and derepressed/induced by glycerol but much more highly expressed. Moreover, LBCM1105 aerobically growing on glycerol was found to produce ethanol, providing a redox escape to compensate the redox imbalance at the level of cyanide-resistant respiration (CRR) and glycerol 3P shuttle. This work is critical for understanding the utilization of glycerol by non-Saccharomyces yeasts being indispensable to consider their industrial application feeding on biodiesel residue.

Structural features of the aromatic/arginine constriction in the aquaglyceroporin GintAQPF2 are responsible for glycerol impermeability in arbuscular mycorrhizal symbiosis.

Carbon transport in arbuscular mycorrhizal (AM) symbiosis is of fundamental importance. However, the role of glycerol transport in AM symbiosis has not yet been resolved. Glycerol transport across the cell membrane is mediated by aquaglyceroporins (AQGPs), whereas our previous study revealed that it was disfavoured by GintAQPF2, an AQGP from AM fungi (AMF). Here, we analysed the function of two amino acid residues in the aromatic/arginine (ar/R) constriction known as the major selectivity filter in AQGPs. Replacement of phenylalanine-94 (Phe-94) by alanine (Ala) enlarged the diameter of the ar/R constriction and resulted in an increased intracellular glycerol accumulation and thus survival rate of yeast cells at high glycerol levels, while individual or joint replacement of Phe-94 and Ala-234 by tryptophan and glycine induced a closed state of GintAQPF2, suggesting that the potential double gates (Phe94-Phe243 and arginine-249) of the ar/R constriction also likely determined solute permeability. To figure out whether GintAQPF2 functions were relevant to the establishment of AM symbiosis, genomic analyses of four representative fungi with different lifestyles were performed. We found that glycerol facilitators existed in the facultative fungi (the ectomycorrhizal fungus Laccaria bicolor and hemibiotrophic pathogen Magnaporthe oryzae), but not in the obligatory fungi (the AMF Rhizophagus irregularis and necrotrophic pathogen Fusarium verticillioides), revealing a conserved pattern of glycerol transport in symbionts and pathogens. Our results suggested that glycerol blocks due to the special structural features of the ar/R constriction in the only AMF AQGP could potentially play a role in the establishment of AM symbiosis.

The role of glycerol transporters in yeast cells in various physiological and stress conditions.

Small and uncharged glycerol is an important molecule for yeast metabolism and osmoadaptation. Using a series of S. cerevisiae BY4741-derived mutants lacking genes encoding a glycerol exporter (Fps1p) and/or importer (Stl1p) and/or the last kinase of the HOG pathway (Hog1p), we studied their phenotypes and various physiological characteristics with the aim of finding new roles for glycerol transporters. Though the triple mutant hog1Δ stl1Δ fps1Δ was viable, it was highly sensitive to various stresses. Our results showed that the function of both Stl1p and Fps1p transporters contributes to the cell ability to survive during the transfer into the state of anhydrobiosis, and that the deletion of FPS1 decreases the cell's tolerance of hyperosmotic stress. The deletion of STL1 results in a slight increase in cell size and in a substantial increase in intracellular pH. Taken together, our results suggest that the fluxes of glycerol in both directions across the plasma membrane exist in yeast cells simultaneously, and the export or import predominates according to the actual specific conditions.

Aquaglyceroporin3-mediated glycerol transport and skin function / 第二军医大学学报

Aquaglyceroporin3 (AQP3), a dual function water channel, can transport both water molecule and other small molecular substances such as glycerol. AQP3-mediated glycerol transport in skin is very important for skin function, whose absence can lead to dry skin, decreased elasticity, and impaired barrier function, and whose overexpression is related to higher risk of skin tumorigenesis. The multiple roles of AQP3 in skin function make it a potential target in treatment of skin disease and development of cosmetics. This paper reviews the characteristics, function, application, and research perspective of AQP3.

Aquaglyceroporin3-mediated glycerol transport and skin function / 第二军医大学学报

Aquaglyceroporin3(AQP3),a dual function water channel,can transport both water molecule and other small molecular substances such as glycerol.AQP3-mediated glycerol transport in skin is very important for skin function,whose absence can lead to dry skin,decreased elasticity,and impaired barrier function,and whose overexpression is related to higher risk of skin tumorigenesis.The multiple roles of AQP3 in skin function make it a potential target in treatment of skin disease and development of cosmetics.This paper reviews the characteristics,function,application,and research perspective of AQP3.