The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Juquan Jiang - One of the best experts on this subject based on the ideXlab platform.
-
characterization of a functionally unknown arginine Aspartate Aspartate family protein from halobacillus andaensis and functional analysis of its conserved arginine Aspartate residues
Frontiers in Microbiology, 2018Co-Authors: Li Shao, Zhenglai Zhang, Fankui Meng, Huiwen Chen, Lin Meng, Heba Abdelmotaal, Jin Chen, Tong Xu, Juquan JiangAbstract:Arginine-Aspartate-Aspartate (RDD) family representing a category of transmembrane proteins containing one highly conserved arginine and two highly conserved Aspartates has been functionally uncharacterized as yet. Here we present the characterization of a member of this family designated RDD from the moderate halophile Halobacillus andaensis NEAU-ST10-40T and report for the first time that RDD should function as a novel Na+(Li+, K+)/H+ antiporter. It's more interesting whether the highly conserved arginine/Aspartate residues among the whole family or between RDD and its selected homologs are related to the protein function. Therefore, we analyzed their roles in the cation-transporting activity through site-directed mutagenesis and found that D154, R124, R129 and D158 are indispensable for Na+(Li+, K+)/H+ antiport activity whereas neither R35 nor D42 is involved in Na+(Li+, K+)/H+ antiport activity. As a dual representative of Na+(Li+, K+)/H+ antiporters and RDD family proteins, the characterization of RDD and analysis of its important residues will positively contribute to the knowledge of the cation-transporting mechanisms of this novel antiporter and the roles of highly conserved arginine/Aspartate residues in the functions of RDD family proteins.
-
Table_1_Characterization of a Functionally Unknown Arginine–Aspartate–Aspartate Family Protein From Halobacillus andaensis and Functional Analysis of Its Conserved Arginine/Aspartate Residues.PDF
2018Co-Authors: Li Shao, Zhenglai Zhang, Fankui Meng, Huiwen Chen, Lin Meng, Jin Chen, Heba Abdel-motaal, Juquan JiangAbstract:Arginine–Aspartate–Aspartate (RDD) family, representing a category of transmembrane proteins containing one highly conserved arginine and two highly conserved Aspartates, has been functionally uncharacterized as yet. Here we present the characterization of a member of this family designated RDD from the moderate halophile Halobacillus andaensis NEAU-ST10-40T and report for the first time that RDD should function as a novel Na+(Li+, K+)/H+ antiporter. It’s more interesting whether the highly conserved arginine/Aspartate residues among the whole family or between RDD and its selected homologs are related to the protein function. Therefore, we analyzed their roles in the cation-transporting activity through site-directed mutagenesis and found that D154, R124, R129, and D158 are indispensable for Na+(Li+, K+)/H+ antiport activity whereas neither R35 nor D42 is involved in Na+(Li+, K+)/H+ antiport activity. As a dual representative of Na+(Li+, K+)/H+ antiporters and RDD family proteins, the characterization of RDD and the analysis of its important residues will positively contribute to the knowledge of the cation-transporting mechanisms of this novel antiporter and the roles of highly conserved arginine/Aspartate residues in the functions of RDD family proteins.
Lucas B Sullivan - One of the best experts on this subject based on the ideXlab platform.
-
Aspartate is an endogenous metabolic limitation for tumour growth
Nature Cell Biology, 2018Co-Authors: Lucas B Sullivan, Alba Luengo, Laura V Danai, Lauren N Bush, Frances F Diehl, Aaron M Hosios, Allison N Lau, Sarah Elmiligy, Scott E MalstromAbstract:Defining the metabolic limitations of tumour growth will help to develop cancer therapies1. Cancer cells proliferate slower in tumours than in standard culture conditions, indicating that a metabolic limitation may restrict cell proliferation in vivo. Aspartate synthesis can limit cancer cell proliferation when respiration is impaired2–4; however, whether acquiring Aspartate is endogenously limiting for tumour growth is unknown. We confirm that Aspartate has poor cell permeability, which prevents environmental acquisition, whereas the related amino acid asparagine is available to cells in tumours, but cancer cells lack asparaginase activity to convert asparagine to Aspartate. Heterologous expression of guinea pig asparaginase 1 (gpASNase1), an enzyme that produces Aspartate from asparagine5, confers the ability to use asparagine to supply intracellular Aspartate to cancer cells in vivo. Tumours expressing gpASNase1 grow at a faster rate, indicating that Aspartate acquisition is an endogenous metabolic limitation for the growth of some tumours. Tumours expressing gpASNase1 are also refractory to the growth suppressive effects of metformin, suggesting that metformin inhibits tumour growth by depleting Aspartate. These findings suggest that therapeutic Aspartate suppression could be effective to treat cancer.
Scott E Malstrom - One of the best experts on this subject based on the ideXlab platform.
-
Aspartate is an endogenous metabolic limitation for tumour growth
Nature Cell Biology, 2018Co-Authors: Lucas B Sullivan, Alba Luengo, Laura V Danai, Lauren N Bush, Frances F Diehl, Aaron M Hosios, Allison N Lau, Sarah Elmiligy, Scott E MalstromAbstract:Defining the metabolic limitations of tumour growth will help to develop cancer therapies1. Cancer cells proliferate slower in tumours than in standard culture conditions, indicating that a metabolic limitation may restrict cell proliferation in vivo. Aspartate synthesis can limit cancer cell proliferation when respiration is impaired2–4; however, whether acquiring Aspartate is endogenously limiting for tumour growth is unknown. We confirm that Aspartate has poor cell permeability, which prevents environmental acquisition, whereas the related amino acid asparagine is available to cells in tumours, but cancer cells lack asparaginase activity to convert asparagine to Aspartate. Heterologous expression of guinea pig asparaginase 1 (gpASNase1), an enzyme that produces Aspartate from asparagine5, confers the ability to use asparagine to supply intracellular Aspartate to cancer cells in vivo. Tumours expressing gpASNase1 grow at a faster rate, indicating that Aspartate acquisition is an endogenous metabolic limitation for the growth of some tumours. Tumours expressing gpASNase1 are also refractory to the growth suppressive effects of metformin, suggesting that metformin inhibits tumour growth by depleting Aspartate. These findings suggest that therapeutic Aspartate suppression could be effective to treat cancer.
Caroline M Jonsson - One of the best experts on this subject based on the ideXlab platform.
-
adsorption of l Aspartate to rutile α tio2 experimental and theoretical surface complexation studies
Geochimica et Cosmochimica Acta, 2010Co-Authors: Caroline M Jonsson, Christopher L Jonsson, Charlene F Estrada, Dimitri A Sverjensky, James H Cleaves, Robert M HazenAbstract:Abstract Interactions between aqueous amino acids and mineral surfaces influence many geochemical processes from biomineralization to the origin of life. However, the specific reactions involved and the attachment mechanisms are mostly unknown. We have studied the adsorption of l -Aspartate on the surface of rutile (α-TiO 2 , pH PPZC = 5.4) in NaCl(aq) over a wide range of pH, ligand-to-solid ratio and ionic strength, using potentiometric titrations and batch adsorption experiments. The adsorption is favored below pH 6 with a maximum of 1.2 μmol of adsorbed Aspartate per m 2 of rutile at pH 4 in our experiments. The adsorption decreases at higher pH because the negatively charged Aspartate molecule is repelled by the negatively charged rutile surface above pH PPZC . At pH values of 3–5, Aspartate adsorption increases with decreasing ionic strength. The adsorption of Aspartate on rutile is very similar to that previously published for glutamate ( Jonsson et al., 2009 ). An extended triple-layer model was used to provide a quantitative thermodynamic characterization of the Aspartate adsorption data. Two reaction stoichiometries identical in reaction stoichiometry to those for glutamate were needed. At low surface coverages, Aspartate, like glutamate, may form a bridging-bidentate surface species binding through both carboxyl groups, i.e. “lying down” on the rutile surface. At high surface coverages, the reaction stoichiometry for Aspartate was interpreted differently compared to glutamate: it likely involves an outer-sphere or hydrogen bonded Aspartate surface species, as opposed to a partly inner-sphere complex for glutamate. Both the proposed Aspartate species are qualitatively consistent with previously published ATR–FTIR spectroscopic results for Aspartate on amorphous titanium dioxide. The surface complexation model for Aspartate was tested against experimental data for the potentiometric titration of Aspartate in the presence of rutile. In addition, the model correctly predicted a decrease of the isoelectric point with increased Aspartate concentration consistent with previously published studies of the Aspartate–anatase system. Prediction of the surface speciation of Aspartate on rutile indicates that the relative proportions of the two complexes are a strong function of environmental conditions, which should be taken into account in considerations of geochemical systems involving the interactions of biomolecules and minerals in electrolyte solutions.
Li Shao - One of the best experts on this subject based on the ideXlab platform.
-
characterization of a functionally unknown arginine Aspartate Aspartate family protein from halobacillus andaensis and functional analysis of its conserved arginine Aspartate residues
Frontiers in Microbiology, 2018Co-Authors: Li Shao, Zhenglai Zhang, Fankui Meng, Huiwen Chen, Lin Meng, Heba Abdelmotaal, Jin Chen, Tong Xu, Juquan JiangAbstract:Arginine-Aspartate-Aspartate (RDD) family representing a category of transmembrane proteins containing one highly conserved arginine and two highly conserved Aspartates has been functionally uncharacterized as yet. Here we present the characterization of a member of this family designated RDD from the moderate halophile Halobacillus andaensis NEAU-ST10-40T and report for the first time that RDD should function as a novel Na+(Li+, K+)/H+ antiporter. It's more interesting whether the highly conserved arginine/Aspartate residues among the whole family or between RDD and its selected homologs are related to the protein function. Therefore, we analyzed their roles in the cation-transporting activity through site-directed mutagenesis and found that D154, R124, R129 and D158 are indispensable for Na+(Li+, K+)/H+ antiport activity whereas neither R35 nor D42 is involved in Na+(Li+, K+)/H+ antiport activity. As a dual representative of Na+(Li+, K+)/H+ antiporters and RDD family proteins, the characterization of RDD and analysis of its important residues will positively contribute to the knowledge of the cation-transporting mechanisms of this novel antiporter and the roles of highly conserved arginine/Aspartate residues in the functions of RDD family proteins.
-
Table_1_Characterization of a Functionally Unknown Arginine–Aspartate–Aspartate Family Protein From Halobacillus andaensis and Functional Analysis of Its Conserved Arginine/Aspartate Residues.PDF
2018Co-Authors: Li Shao, Zhenglai Zhang, Fankui Meng, Huiwen Chen, Lin Meng, Jin Chen, Heba Abdel-motaal, Juquan JiangAbstract:Arginine–Aspartate–Aspartate (RDD) family, representing a category of transmembrane proteins containing one highly conserved arginine and two highly conserved Aspartates, has been functionally uncharacterized as yet. Here we present the characterization of a member of this family designated RDD from the moderate halophile Halobacillus andaensis NEAU-ST10-40T and report for the first time that RDD should function as a novel Na+(Li+, K+)/H+ antiporter. It’s more interesting whether the highly conserved arginine/Aspartate residues among the whole family or between RDD and its selected homologs are related to the protein function. Therefore, we analyzed their roles in the cation-transporting activity through site-directed mutagenesis and found that D154, R124, R129, and D158 are indispensable for Na+(Li+, K+)/H+ antiport activity whereas neither R35 nor D42 is involved in Na+(Li+, K+)/H+ antiport activity. As a dual representative of Na+(Li+, K+)/H+ antiporters and RDD family proteins, the characterization of RDD and the analysis of its important residues will positively contribute to the knowledge of the cation-transporting mechanisms of this novel antiporter and the roles of highly conserved arginine/Aspartate residues in the functions of RDD family proteins.
