The Experts below are selected from a list of 81 Experts worldwide ranked by ideXlab platform
Karen A Kidd - One of the best experts on this subject based on the ideXlab platform.
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tissue content of thiol containing amino acids predicts methylmercury in aquatic invertebrates
Science of The Total Environment, 2019Co-Authors: Jennifer C Thera, Karen A Kidd, Robert F P Bertolo, Nelson J OdriscollAbstract:Abstract Aquatic invertebrates vary in methylmercury (MeHg) levels among systems which has been attributed, in part, to environmental conditions, but may also be linked to differences in their biochemical composition. As MeHg is known to bind to thiol-containing amino acids such as cysteine in proteins of fish, our objective was to determine if these amino acids explain MeHg variability among aquatic invertebrate taxa. Benthic macroinvertebrates from diverse functional feeding groups and bulk zooplankton were collected from six acidic lakes in Kejimkujik National Park, Nova Scotia, Canada, and analyzed for MeHg, cysteine (as cysteic acid), Methionine (as Methionine Sulfone), and nitrogen (relative trophic level, δ 15 N) and carbon (carbon source, δ 13 C) isotopes. MeHg was significantly and positively related to cysteine or Methionine in zooplankton, caddisfly and stonefly tissues (R 2 from 0.24 to 0.57). In addition, Methionine or cysteine in combination with δ 15 N and/or δ 13 C were better predictors of MeHg levels in stoneflies, mayflies, caddisflies and zooplankton among these lakes (R 2 adj = 0.25–0.91). Overall, these novel findings suggest that the variability in MeHg of aquatic invertebrates can be explained, in part, by their tissue levels of thiol-containing amino acids.
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quantification of sulphur amino acids by ultra high performance liquid chromatography in aquatic invertebrates
Analytical Biochemistry, 2017Co-Authors: Jennifer C Thera, Elaine M Dodgelynch, Karen A Kidd, Robert F P BertoloAbstract:Abstract We examined the performance of an ultra-high performance liquid chromatography method to quantify protein-bound sulphur amino acids in zooplankton. Both cysteic acid and Methionine Sulfone were linear from 5 to 250 pmol (r2 = 0.99), with a method detection limit of 13 pmol and 9 pmol, respectively. Although there was no matrix effect on linearity, adjacent peaks and co-eluting noise from the invertebrate proteins increased the detection limits when compared to common standards. Overall, performance characteristics were reproducible and accurate, and provide a means for quantifying sulphur amino acids in aquatic invertebrates, an understudied group.
Robert F P Bertolo - One of the best experts on this subject based on the ideXlab platform.
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tissue content of thiol containing amino acids predicts methylmercury in aquatic invertebrates
Science of The Total Environment, 2019Co-Authors: Jennifer C Thera, Karen A Kidd, Robert F P Bertolo, Nelson J OdriscollAbstract:Abstract Aquatic invertebrates vary in methylmercury (MeHg) levels among systems which has been attributed, in part, to environmental conditions, but may also be linked to differences in their biochemical composition. As MeHg is known to bind to thiol-containing amino acids such as cysteine in proteins of fish, our objective was to determine if these amino acids explain MeHg variability among aquatic invertebrate taxa. Benthic macroinvertebrates from diverse functional feeding groups and bulk zooplankton were collected from six acidic lakes in Kejimkujik National Park, Nova Scotia, Canada, and analyzed for MeHg, cysteine (as cysteic acid), Methionine (as Methionine Sulfone), and nitrogen (relative trophic level, δ 15 N) and carbon (carbon source, δ 13 C) isotopes. MeHg was significantly and positively related to cysteine or Methionine in zooplankton, caddisfly and stonefly tissues (R 2 from 0.24 to 0.57). In addition, Methionine or cysteine in combination with δ 15 N and/or δ 13 C were better predictors of MeHg levels in stoneflies, mayflies, caddisflies and zooplankton among these lakes (R 2 adj = 0.25–0.91). Overall, these novel findings suggest that the variability in MeHg of aquatic invertebrates can be explained, in part, by their tissue levels of thiol-containing amino acids.
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quantification of sulphur amino acids by ultra high performance liquid chromatography in aquatic invertebrates
Analytical Biochemistry, 2017Co-Authors: Jennifer C Thera, Elaine M Dodgelynch, Karen A Kidd, Robert F P BertoloAbstract:Abstract We examined the performance of an ultra-high performance liquid chromatography method to quantify protein-bound sulphur amino acids in zooplankton. Both cysteic acid and Methionine Sulfone were linear from 5 to 250 pmol (r2 = 0.99), with a method detection limit of 13 pmol and 9 pmol, respectively. Although there was no matrix effect on linearity, adjacent peaks and co-eluting noise from the invertebrate proteins increased the detection limits when compared to common standards. Overall, performance characteristics were reproducible and accurate, and provide a means for quantifying sulphur amino acids in aquatic invertebrates, an understudied group.
Jennifer C Thera - One of the best experts on this subject based on the ideXlab platform.
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tissue content of thiol containing amino acids predicts methylmercury in aquatic invertebrates
Science of The Total Environment, 2019Co-Authors: Jennifer C Thera, Karen A Kidd, Robert F P Bertolo, Nelson J OdriscollAbstract:Abstract Aquatic invertebrates vary in methylmercury (MeHg) levels among systems which has been attributed, in part, to environmental conditions, but may also be linked to differences in their biochemical composition. As MeHg is known to bind to thiol-containing amino acids such as cysteine in proteins of fish, our objective was to determine if these amino acids explain MeHg variability among aquatic invertebrate taxa. Benthic macroinvertebrates from diverse functional feeding groups and bulk zooplankton were collected from six acidic lakes in Kejimkujik National Park, Nova Scotia, Canada, and analyzed for MeHg, cysteine (as cysteic acid), Methionine (as Methionine Sulfone), and nitrogen (relative trophic level, δ 15 N) and carbon (carbon source, δ 13 C) isotopes. MeHg was significantly and positively related to cysteine or Methionine in zooplankton, caddisfly and stonefly tissues (R 2 from 0.24 to 0.57). In addition, Methionine or cysteine in combination with δ 15 N and/or δ 13 C were better predictors of MeHg levels in stoneflies, mayflies, caddisflies and zooplankton among these lakes (R 2 adj = 0.25–0.91). Overall, these novel findings suggest that the variability in MeHg of aquatic invertebrates can be explained, in part, by their tissue levels of thiol-containing amino acids.
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quantification of sulphur amino acids by ultra high performance liquid chromatography in aquatic invertebrates
Analytical Biochemistry, 2017Co-Authors: Jennifer C Thera, Elaine M Dodgelynch, Karen A Kidd, Robert F P BertoloAbstract:Abstract We examined the performance of an ultra-high performance liquid chromatography method to quantify protein-bound sulphur amino acids in zooplankton. Both cysteic acid and Methionine Sulfone were linear from 5 to 250 pmol (r2 = 0.99), with a method detection limit of 13 pmol and 9 pmol, respectively. Although there was no matrix effect on linearity, adjacent peaks and co-eluting noise from the invertebrate proteins increased the detection limits when compared to common standards. Overall, performance characteristics were reproducible and accurate, and provide a means for quantifying sulphur amino acids in aquatic invertebrates, an understudied group.
Kristy L Hentchel - One of the best experts on this subject based on the ideXlab platform.
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Phosphinothricin Acetyltransferases Identified Using In Vivo, In Vitro, and Bioinformatic Analyses
Applied and environmental microbiology, 2016Co-Authors: Chelsey M. Vandrisse, Kristy L Hentchel, Jorge C. Escalante-semerenaAbstract:Acetylation of small molecules is widespread in nature, and in some cases, cells use this process to detoxify harmful chemicals. Streptomyces species utilize a Gcn5 N-acetyltransferase (GNAT), known as Bar, to acetylate and detoxify a self-produced toxin, phosphinothricin (PPT), a glutamate analogue. Bar homologues, such as MddA from Salmonella enterica, acetylate Methionine analogues such as Methionine sulfoximine (MSX) and Methionine Sulfone (MSO), but not PPT, even though Bar homologues are annotated as PPT acetyltransferases. S. enterica was used as a heterologous host to determine whether or not putative PPT acetyltransferases from various sources could acetylate PPT, MSX, and MSO. In vitro and in vivo analyses identified substrates acetylated by putative PPT acetyltransferases from Deinococcus radiodurans (DR_1057 and DR_1182) and Geobacillus kaustophilus (GK0593 and GK2920). In vivo, synthesis of DR_1182, GK0593, and GK2920 blocked the inhibitory effects of PPT, MSX, and MSO. In contrast, DR_1057 did not detoxify any of the above substrates. Results of in vitro studies were consistent with the in vivo results. In addition, phylogenetic analyses were used to predict the functionality of annotated PPT acetyltransferases in Burkholderia xenovorans, Bacillus subtilis, Staphylococcus aureus, Acinetobacter baylyi, and Escherichia coli IMPORTANCE: The work reported here provides an example of the use of a heterologous system for the identification of enzyme function. Many members of this superfamily of proteins do not have a known function, or it has been annotated solely on the basis of sequence homology to previously characterized enzymes. The critical role of Gcn5 N-acetyltransferases (GNATs) in the modulation of central metabolic processes, and in controlling metabolic stress, necessitates approaches that can reveal their physiological role. The combination of in vivo, in vitro, and bioinformatics approaches reported here identified GNATs that can acetylate and detoxify phosphinothricin.
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in salmonella enterica the gcn5 related acetyltransferase mdda formerly ynca acetylates Methionine sulfoximine and Methionine Sulfone blocking their toxic effects
Journal of Bacteriology, 2015Co-Authors: Kristy L Hentchel, Jorge C EscalantesemerenaAbstract:Protein and small-molecule acylation reactions are widespread in nature. Many of the enzymes catalyzing acylation reactions belong to the Gcn5-related N-acetyltransferase (GNAT; PF00583) family, named after the yeast Gcn5 protein. The genome of Salmonella enterica serovar Typhimurium LT2 encodes 26 GNATs, 11 of which have no known physiological role. Here, we provide in vivo and in vitro evidence for the role of the MddA (Methionine derivative detoxifier; formerly YncA) GNAT in the detoxification of oxidized forms of Methionine, including Methionine sulfoximine (MSX) and Methionine Sulfone (MSO). MSX and MSO inhibited the growth of an S. enterica ΔmddA strain unless glutamine or Methionine was present in the medium. We used an in vitro spectrophotometric assay and mass spectrometry to show that MddA acetylated MSX and MSO. An mddA+ strain displayed biphasic growth kinetics in the presence of MSX and glutamine. Deletion of two amino acid transporters (GlnHPQ and MetNIQ) in a ΔmddA strain restored growth in the presence of MSX. Notably, MSO was transported by GlnHPQ but not by MetNIQ. In summary, MddA is the mechanism used by S. enterica to respond to oxidized forms of Methionine, which MddA detoxifies by acetyl coenzyme A-dependent acetylation.
Jorge C Escalantesemerena - One of the best experts on this subject based on the ideXlab platform.
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in salmonella enterica the gcn5 related acetyltransferase mdda formerly ynca acetylates Methionine sulfoximine and Methionine Sulfone blocking their toxic effects
Journal of Bacteriology, 2015Co-Authors: Kristy L Hentchel, Jorge C EscalantesemerenaAbstract:Protein and small-molecule acylation reactions are widespread in nature. Many of the enzymes catalyzing acylation reactions belong to the Gcn5-related N-acetyltransferase (GNAT; PF00583) family, named after the yeast Gcn5 protein. The genome of Salmonella enterica serovar Typhimurium LT2 encodes 26 GNATs, 11 of which have no known physiological role. Here, we provide in vivo and in vitro evidence for the role of the MddA (Methionine derivative detoxifier; formerly YncA) GNAT in the detoxification of oxidized forms of Methionine, including Methionine sulfoximine (MSX) and Methionine Sulfone (MSO). MSX and MSO inhibited the growth of an S. enterica ΔmddA strain unless glutamine or Methionine was present in the medium. We used an in vitro spectrophotometric assay and mass spectrometry to show that MddA acetylated MSX and MSO. An mddA+ strain displayed biphasic growth kinetics in the presence of MSX and glutamine. Deletion of two amino acid transporters (GlnHPQ and MetNIQ) in a ΔmddA strain restored growth in the presence of MSX. Notably, MSO was transported by GlnHPQ but not by MetNIQ. In summary, MddA is the mechanism used by S. enterica to respond to oxidized forms of Methionine, which MddA detoxifies by acetyl coenzyme A-dependent acetylation.