The Experts below are selected from a list of 339 Experts worldwide ranked by ideXlab platform
Matthew D. Collins - One of the best experts on this subject based on the ideXlab platform.
-
Arthrobacter rhombi sp. nov., isolated from Greenland halibut (Reinhardtius hippoglossoides).
International Journal of Systematic and Evolutionary Microbiology, 1999Co-Authors: Carlos R. Osorio, Juan L. Barja, Roger A. Hutson, Matthew D. CollinsAbstract:Two strains of a hitherto undescribed Gram-positive Coryneform Bacterium isolated from Greenland halibut (Reinhardtius hippoglossoides) were characterized by phenotypic and molecular taxonomic methods. Comparative 16S rRNA gene sequencing studies demonstrated that the unknown strains constitute a new line within the genus Arthrobacter. The nearest relatives of the Bacterium from fish were members of the Arthrobacter nicotianael Arthrobacter sulfureus group. The unknown Bacterium was readily distinguished from these species by phenotypic methods. Based on phylogenetic and phenotypic evidence, it is proposed that the unknown Bacterium be classified as Arthrobacter rhombi sp. nov. The type strain of Arthrobacter rhombi is CCUG 38813T.
-
Phenotypic and Phylogenetic Characterization of a New CoryneBacterium Species from Dogs: Description of CoryneBacterium auriscanis sp. nov.
Journal of clinical microbiology, 1999Co-Authors: Matthew D. Collins, Enevold Falsen, Paul A. Lawson, Lesley Hoyles, Robert L. Robson, Geoffrey FosterAbstract:Six strains of a previously undescribed catalase-positive Coryneform Bacterium isolated from clinical specimens from dogs were characterized by phenotypic and molecular genetic methods. Biochemical and chemotaxonomic studies revealed that the unknown Bacterium belonged to the genus CoryneBacterium sensu stricto. Comparative 16S rRNA gene sequencing showed that the six strains were genealogically highly related and constitute a new subline within the genus CoryneBacterium; this subline is close to but distinct from C. falsenii, C. jeikeium, and C. urealyticum. The unknown Bacterium from dogs was distinguished from all currently validated CoryneBacterium species by phenotypic tests including electrophoretic analysis of whole-cell proteins. On the basis of phylogenetic and phenotypic evidence, it is proposed that the unknown Bacterium be classified as a new species, CoryneBacterium auriscanis. The type strain of C. auriscanis is CCUG 39938T.
-
Phenotypic and phylogenetic characterization of a new CoryneBacterium species from dogs: description of CoryneBacterium auriscanis sp. nov
1999Co-Authors: Matthew D. Collins, Enevold Falsen, Paul A. Lawson, Lesley Hoyles, Robert L. Robson, Geoffrey FosterAbstract:Six strains of a previously undescribed catalase-positive Coryneform Bacterium isolated from clinical spec-imens from dogs were characterized by phenotypic and molecular genetic methods. Biochemical and chemo-taxonomic studies revealed that the unknown Bacterium belonged to the genus CoryneBacterium sensu stricto. Comparative 16S rRNA gene sequencing showed that the six strains were genealogically highly related and constitute a new subline within the genus CoryneBacterium; this subline is close to but distinct from C. falsenii, C. jeikeium, and C. urealyticum. The unknown Bacterium from dogs was distinguished from all currently validated CoryneBacterium species by phenotypic tests including electrophoretic analysis of whole-cell proteins. On the basis of phylogenetic and phenotypic evidence, it is proposed that the unknown Bacterium be classified as a new species, CoryneBacterium auriscanis. The type strain of C. auriscanis is CCUG 39938T. The genus CoryneBacterium contains many species which have long been recognized as pathogens of humans and/or animals. During the past two decades, the taxonomy of this important group of organisms has undergone dramatic change. In particular, the use of molecular chemical and molecular genetic methodologies has facilitated a much tighter circum
-
AureoBacterium resistens sp. nov., exhibiting vancomycin resistance and teicoplanin susceptibility
1998Co-Authors: Guido Funke, Norbert Weiss, Paul A. Lawson, Frederick S Nolte, Matthew D. CollinsAbstract:Abstract Two similar strains of a Coryneform Bacterium were isolated from human clinical material. Both strains were resistant to vancomycin but susceptible to teicoplanin. Detailed biochemical, chemotaxonomical, and molecular genetic investigations revealed that both isolates were members of a hitherto undescribed species of the genus AureoBacterium. The name AureoBacterium resistens sp. nov. is proposed for the new Bacterium and the type strain is CCUG 38312. ß 1998 Federation of European Microbiological Societies. Published by Elsevier Science B.V
-
actinomyces europaeus sp nov isolated from human clinical specimens
International Journal of Systematic and Evolutionary Microbiology, 1997Co-Authors: Guido Funke, Cristina Pascual, Norbert Weiss, Eva Akervall, Luc Sabbe, Leo M Schouls, Enevold Falsen, Nerea Alvarez, Matthew D. CollinsAbstract:Ten strains of a hitherto undescribed catalase-negative, facultatively anaerobic, Coryneform Bacterium were isolated or collected by workers at three European clinical bacteriology laboratories or reference centers. These strains were isolated from humans, and most came from abscess material. Biochemical and chemotaxonomic characterization revealed that the strains belonged to the genus Actinomyces. The phenotypic features of the 10 strains were incompatible with the descriptions of the previously established Actinomyces species. A comparative 16S rRNA gene sequence analysis demonstrated that the previously undescribed strains constitute a new line in the genus Actinomyces. The name Actinomyces europaeus sp. nov. is proposed for these clinical isolates. The type strain is CCUG 32789A.
Christian P Whitman - One of the best experts on this subject based on the ideXlab platform.
-
Kinetic, Mutational, and Structural Analysis of Malonate Semialdehyde Decarboxylase from Coryneform Bacterium Strain FG41: Mechanistic Implications for the Decarboxylase and Hydratase Activities
2016Co-Authors: Youzhong Guo, Hector Serrano, Gerrit J Poelarends, William H Johnson, Marvin L Hackert, Christian P WhitmanAbstract:Malonate semialdehyde decarboxylase from Pseudomonas pavonaceae 170 (designated Pp MSAD) is in a bacterial catabolic pathway for the nematicide 1,3-dichloropropene. MSAD has two known activities: it catalyzes the metal ion-independent decarboxylation of malonate semialdehyde to produce acetaldehyde and carbon dioxide and a low-level hydration of 2-oxo-3-pentynoate to yield acetopyruvate. The latter activity is not known to be biologically relevant. Previous studies identified Pro-1, Asp-37, and a pair of arginines (Arg-73 and Arg-75) as critical residues in these activities. In terms of pairwise sequence, MSAD from Coryneform Bacterium strain FG41 (designated FG41 MSAD) is 38% identical with the Pseudomonas enzyme, including Pro-1 and Asp-37. However, Gln-73 replaces Arg-73, and the second arginine is shifted to Arg-76 by the insertion of a glycine. To determine how these changes relate to the activities of FG41 MSAD, the gene was cloned and the enzyme expressed and characterized. The enzyme has a comparable decarboxylase activity but a significantly reduced hydratase activity. Mutagenesis along with crystal structures of the native enzyme (2.0 Å resolution) and the enzyme modified by a 3-oxopropanoate moiety (resulting from the incubation of the enzyme and 3-bromopropiolate) (2.2 Å resolution) provided a structural basis. The roles of Pro-1 and Asp-37 are likely the same as those proposed for Pp MSAD. However, the side chains of Thr-72, Gln-73, and Tyr-123 replace those of Arg-73 and Arg-75 in the mechanism and play a role in binding and catalysis. The structures also show that Arg-76 is likely too distant to play a direct role in the mechanism. FG41 MSAD is the second functionally annotated homologue in the MSAD family of the tautomerase superfamily and could represent a new subfamily
-
kinetic mutational and structural analysis of malonate semialdehyde decarboxylase from Coryneform Bacterium strain fg41 mechanistic implications for the decarboxylase and hydratase activities
Biochemistry, 2013Co-Authors: Youzhong Guo, Hector Serrano, Gerrit J Poelarends, William H Johnson, Marvin L Hackert, Christian P WhitmanAbstract:Malonate semialdehyde decarboxylase from Pseudomonas pavonaceae 170 (designated Pp MSAD) is in a bacterial catabolic pathway for the nematicide 1,3-dichloropropene. MSAD has two known activities: it catalyzes the metal ion-independent decarboxylation of malonate semialdehyde to produce acetaldehyde and carbon dioxide and a low-level hydration of 2-oxo-3-pentynoate to yield acetopyruvate. The latter activity is not known to be biologically relevant. Previous studies identified Pro-1, Asp-37, and a pair of arginines (Arg-73 and Arg-75) as critical residues in these activities. In terms of pairwise sequence, MSAD from Coryneform Bacterium strain FG41 (designated FG41 MSAD) is 38% identical with the Pseudomonas enzyme, including Pro-1 and Asp-37. However, Gln-73 replaces Arg-73, and the second arginine is shifted to Arg-76 by the insertion of a glycine. To determine how these changes relate to the activities of FG41 MSAD, the gene was cloned and the enzyme expressed and characterized. The enzyme has a comparable decarboxylase activity but a significantly reduced hydratase activity. Mutagenesis along with crystal structures of the native enzyme (2.0 A resolution) and the enzyme modified by a 3-oxopropanoate moiety (resulting from the incubation of the enzyme and 3-bromopropiolate) (2.2 A resolution) provided a structural basis. The roles of Pro-1 and Asp-37 are likely the same as those proposed for Pp MSAD. However, the side chains of Thr-72, Gln-73, and Tyr-123 replace those of Arg-73 and Arg-75 in the mechanism and play a role in binding and catalysis. The structures also show that Arg-76 is likely too distant to play a direct role in the mechanism. FG41 MSAD is the second functionally annotated homologue in the MSAD family of the tautomerase superfamily and could represent a new subfamily.
-
cloning expression and characterization of a cis 3 chloroacrylic acid dehalogenase insights into the mechanistic structural and evolutionary relationship between isomer specific 3 chloroacrylic acid dehalogenases
Biochemistry, 2004Co-Authors: Gerrit J Poelarends, Hector Serrano, William H Johnson, Maria D Person, And Alexey G Murzin, Christian P WhitmanAbstract:The gene encoding the cis-3-chloroacrylic acid dehalogenase (cis-CaaD) from Coryneform Bacterium strain FG41 has been cloned and overexpressed, and the enzyme has been purified to homogeneity and subjected to kinetic and mechanistic characterization. Kinetic studies show that cis-CaaD processes cis-3-haloacrylates, but not trans-3-haloacrylates, with a turnover number of ∼10 s-1. The product of the reaction is malonate semialdehyde, which was confirmed by its characteristic 1H NMR spectrum. The enzyme shares low but significant sequence similarity with the previously studied trans-3-chloroacrylic acid dehalogenase (CaaD) and with other members of the 4-oxalocrotonate tautomerase (4-OT) family. While 4-OT and CaaD function as homo- and heterohexamers, respectively, cis-CaaD appears to be a homotrimeric protein as assessed by gel filtration chromatography. On the basis of the known three-dimensional structures and reaction mechanisms of CaaD and 4-OT, a sequence alignment implicated Pro-1, Arg-70, Arg-73, a...
Guido Funke - One of the best experts on this subject based on the ideXlab platform.
-
coryneBacterium canis sp nov isolated from a wound infection caused by a dog bite
International Journal of Systematic and Evolutionary Microbiology, 2010Co-Authors: Guido Funke, Reinhard Frodl, Kathryn Bernard, Ralf Englert, Steffen StengerAbstract:A non-lipophilic, Coryneform Bacterium isolated from a patient's wound caused by a dog bite was characterized by phenotypic, chemotaxonomic and molecular genetic methods. Chemotaxonomic features suggested assignment of the unknown Bacterium to the genus CoryneBacterium. The isolate exhibited the following unusual features, which made it possible to phenotypically differentiate it from all other medically relevant corynebacteria: the Gram stain showed some very filamentous rods (>15 μm in length); some cells exhibited branching; colonies were domed and adherent to agar; the micro-organism was positive for pyrazinamidase, β-glucosidase, α-glucosidase and trypsin but negative for β-galactosidase. 16S rRNA gene sequencing and partial rpoB gene sequencing showed that the closest phylogenetic relative, CoryneBacterium freiburgense, exhibited more than 1.9 % and 17.9 % divergence with the unknown Bacterium, respectively. Based on both phenotypic and molecular genetic data, it is proposed that the isolate should be classified as a novel species, CoryneBacterium canis sp. nov., with the type strain 1170T (=CCUG 58627T =DSM 45402T).
-
coryneBacterium freiburgense sp nov isolated from a wound obtained from a dog bite
International Journal of Systematic and Evolutionary Microbiology, 2009Co-Authors: Guido Funke, Reinhard Frodl, Kathryn Bernard, Ralf EnglertAbstract:A non-lipophilic, Coryneform Bacterium, isolated from a patient's wound obtained from a dog bite, was characterized by phenotypic, chemotaxonomic and molecular genetic methods. Chemotaxonomic features suggested assignment of the unknown Bacterium to the genus CoryneBacterium. The isolate exhibited the following peculiar features which made it possible to differentiate it phenotypically from all other medically relevant corynebacteria: older colonies exhibited a ‘spoke-wheel’ macroscopic morphology, colonies were strongly adherent to blood agar and the strain did not have pyrazinamidase activity, but was positive for β-galactosidase. 16S rRNA gene sequencing showed that the closest phylogenetic relative exhibited more than 3.9 % divergence from the unknown isolate. Based on phenotypic and molecular genetic data, it is proposed that the isolate should be classified as a representative of a novel species, CoryneBacterium freiburgense sp. nov., with strain 1045T (=CCUG 56874T =DSM 45254T) as the type strain.
-
AureoBacterium resistens sp. nov., exhibiting vancomycin resistance and teicoplanin susceptibility
1998Co-Authors: Guido Funke, Norbert Weiss, Paul A. Lawson, Frederick S Nolte, Matthew D. CollinsAbstract:Abstract Two similar strains of a Coryneform Bacterium were isolated from human clinical material. Both strains were resistant to vancomycin but susceptible to teicoplanin. Detailed biochemical, chemotaxonomical, and molecular genetic investigations revealed that both isolates were members of a hitherto undescribed species of the genus AureoBacterium. The name AureoBacterium resistens sp. nov. is proposed for the new Bacterium and the type strain is CCUG 38312. ß 1998 Federation of European Microbiological Societies. Published by Elsevier Science B.V
-
actinomyces europaeus sp nov isolated from human clinical specimens
International Journal of Systematic and Evolutionary Microbiology, 1997Co-Authors: Guido Funke, Cristina Pascual, Norbert Weiss, Eva Akervall, Luc Sabbe, Leo M Schouls, Enevold Falsen, Nerea Alvarez, Matthew D. CollinsAbstract:Ten strains of a hitherto undescribed catalase-negative, facultatively anaerobic, Coryneform Bacterium were isolated or collected by workers at three European clinical bacteriology laboratories or reference centers. These strains were isolated from humans, and most came from abscess material. Biochemical and chemotaxonomic characterization revealed that the strains belonged to the genus Actinomyces. The phenotypic features of the 10 strains were incompatible with the descriptions of the previously established Actinomyces species. A comparative 16S rRNA gene sequence analysis demonstrated that the previously undescribed strains constitute a new line in the genus Actinomyces. The name Actinomyces europaeus sp. nov. is proposed for these clinical isolates. The type strain is CCUG 32789A.
-
Copyright © 1997, American Society for Microbiology CoryneBacterium imitans sp. nov. Isolated from Patients with Suspected Diphtheria
1997Co-Authors: Guido Funke, Roger A. Hutson, Androulla Efstratiou, Danuta Kuklinska, Aruni De Zoysa, Kathryn H. Engler, Matthew D. CollinsAbstract:A 5-month-old boy of a Romanian family traveling via Ukraine to Poland developed a respiratory disease that resembled and that was initially diagnosed as pharyngeal diphtheria. The child recovered after treatment with antidiphtheria antitoxin. A Coryneform Bacterium had been isolated from a nasopharyngeal specimen from the child and was initially identified as an atypical CoryneBacterium diphtheriae strain. Seven adults who had contact with either the child or an adult contact person also developed symptoms of pharyngeal diphtheria, were also treated with antitoxin, and recovered uneventfully. Coryneform bacteria similar to that originating from the index patient were also isolated from the throat swabs of three adults. Detailed biochemical and chemotaxonomic investigations revealed that the Coryneform bacteria belonged to the genus CoryneBacterium and could be differentiated from all other defined species of this genus. Ribotyping and pulsed-field gel electrophoresis demonstrated that all four patients ’ isolates were of clonal origin. The diphtheria toxin gene and its product were not detected either by PCR assays or by the Elek test, making a possible disease association of the CoryneBacterium more unlikely. Comparative 16S rRNA gene sequence analysis revealed that the Coryneform Bacterium represented a new subline within the genus CoryneBacterium, for which the name CoryneBacterium imitans sp. nov. is proposed. The type strain is NCTC 13015 (DSM 44264; CCUG 36877). During the 1990s there has been an ongoing diphtheri
Gerrit J Poelarends - One of the best experts on this subject based on the ideXlab platform.
-
Kinetic, Mutational, and Structural Analysis of Malonate Semialdehyde Decarboxylase from Coryneform Bacterium Strain FG41: Mechanistic Implications for the Decarboxylase and Hydratase Activities
2016Co-Authors: Youzhong Guo, Hector Serrano, Gerrit J Poelarends, William H Johnson, Marvin L Hackert, Christian P WhitmanAbstract:Malonate semialdehyde decarboxylase from Pseudomonas pavonaceae 170 (designated Pp MSAD) is in a bacterial catabolic pathway for the nematicide 1,3-dichloropropene. MSAD has two known activities: it catalyzes the metal ion-independent decarboxylation of malonate semialdehyde to produce acetaldehyde and carbon dioxide and a low-level hydration of 2-oxo-3-pentynoate to yield acetopyruvate. The latter activity is not known to be biologically relevant. Previous studies identified Pro-1, Asp-37, and a pair of arginines (Arg-73 and Arg-75) as critical residues in these activities. In terms of pairwise sequence, MSAD from Coryneform Bacterium strain FG41 (designated FG41 MSAD) is 38% identical with the Pseudomonas enzyme, including Pro-1 and Asp-37. However, Gln-73 replaces Arg-73, and the second arginine is shifted to Arg-76 by the insertion of a glycine. To determine how these changes relate to the activities of FG41 MSAD, the gene was cloned and the enzyme expressed and characterized. The enzyme has a comparable decarboxylase activity but a significantly reduced hydratase activity. Mutagenesis along with crystal structures of the native enzyme (2.0 Å resolution) and the enzyme modified by a 3-oxopropanoate moiety (resulting from the incubation of the enzyme and 3-bromopropiolate) (2.2 Å resolution) provided a structural basis. The roles of Pro-1 and Asp-37 are likely the same as those proposed for Pp MSAD. However, the side chains of Thr-72, Gln-73, and Tyr-123 replace those of Arg-73 and Arg-75 in the mechanism and play a role in binding and catalysis. The structures also show that Arg-76 is likely too distant to play a direct role in the mechanism. FG41 MSAD is the second functionally annotated homologue in the MSAD family of the tautomerase superfamily and could represent a new subfamily
-
kinetic mutational and structural analysis of malonate semialdehyde decarboxylase from Coryneform Bacterium strain fg41 mechanistic implications for the decarboxylase and hydratase activities
Biochemistry, 2013Co-Authors: Youzhong Guo, Hector Serrano, Gerrit J Poelarends, William H Johnson, Marvin L Hackert, Christian P WhitmanAbstract:Malonate semialdehyde decarboxylase from Pseudomonas pavonaceae 170 (designated Pp MSAD) is in a bacterial catabolic pathway for the nematicide 1,3-dichloropropene. MSAD has two known activities: it catalyzes the metal ion-independent decarboxylation of malonate semialdehyde to produce acetaldehyde and carbon dioxide and a low-level hydration of 2-oxo-3-pentynoate to yield acetopyruvate. The latter activity is not known to be biologically relevant. Previous studies identified Pro-1, Asp-37, and a pair of arginines (Arg-73 and Arg-75) as critical residues in these activities. In terms of pairwise sequence, MSAD from Coryneform Bacterium strain FG41 (designated FG41 MSAD) is 38% identical with the Pseudomonas enzyme, including Pro-1 and Asp-37. However, Gln-73 replaces Arg-73, and the second arginine is shifted to Arg-76 by the insertion of a glycine. To determine how these changes relate to the activities of FG41 MSAD, the gene was cloned and the enzyme expressed and characterized. The enzyme has a comparable decarboxylase activity but a significantly reduced hydratase activity. Mutagenesis along with crystal structures of the native enzyme (2.0 A resolution) and the enzyme modified by a 3-oxopropanoate moiety (resulting from the incubation of the enzyme and 3-bromopropiolate) (2.2 A resolution) provided a structural basis. The roles of Pro-1 and Asp-37 are likely the same as those proposed for Pp MSAD. However, the side chains of Thr-72, Gln-73, and Tyr-123 replace those of Arg-73 and Arg-75 in the mechanism and play a role in binding and catalysis. The structures also show that Arg-76 is likely too distant to play a direct role in the mechanism. FG41 MSAD is the second functionally annotated homologue in the MSAD family of the tautomerase superfamily and could represent a new subfamily.
-
cloning expression and characterization of a cis 3 chloroacrylic acid dehalogenase insights into the mechanistic structural and evolutionary relationship between isomer specific 3 chloroacrylic acid dehalogenases
Biochemistry, 2004Co-Authors: Gerrit J Poelarends, Hector Serrano, William H Johnson, Maria D Person, And Alexey G Murzin, Christian P WhitmanAbstract:The gene encoding the cis-3-chloroacrylic acid dehalogenase (cis-CaaD) from Coryneform Bacterium strain FG41 has been cloned and overexpressed, and the enzyme has been purified to homogeneity and subjected to kinetic and mechanistic characterization. Kinetic studies show that cis-CaaD processes cis-3-haloacrylates, but not trans-3-haloacrylates, with a turnover number of ∼10 s-1. The product of the reaction is malonate semialdehyde, which was confirmed by its characteristic 1H NMR spectrum. The enzyme shares low but significant sequence similarity with the previously studied trans-3-chloroacrylic acid dehalogenase (CaaD) and with other members of the 4-oxalocrotonate tautomerase (4-OT) family. While 4-OT and CaaD function as homo- and heterohexamers, respectively, cis-CaaD appears to be a homotrimeric protein as assessed by gel filtration chromatography. On the basis of the known three-dimensional structures and reaction mechanisms of CaaD and 4-OT, a sequence alignment implicated Pro-1, Arg-70, Arg-73, a...
William H Johnson - One of the best experts on this subject based on the ideXlab platform.
-
Kinetic, Mutational, and Structural Analysis of Malonate Semialdehyde Decarboxylase from Coryneform Bacterium Strain FG41: Mechanistic Implications for the Decarboxylase and Hydratase Activities
2016Co-Authors: Youzhong Guo, Hector Serrano, Gerrit J Poelarends, William H Johnson, Marvin L Hackert, Christian P WhitmanAbstract:Malonate semialdehyde decarboxylase from Pseudomonas pavonaceae 170 (designated Pp MSAD) is in a bacterial catabolic pathway for the nematicide 1,3-dichloropropene. MSAD has two known activities: it catalyzes the metal ion-independent decarboxylation of malonate semialdehyde to produce acetaldehyde and carbon dioxide and a low-level hydration of 2-oxo-3-pentynoate to yield acetopyruvate. The latter activity is not known to be biologically relevant. Previous studies identified Pro-1, Asp-37, and a pair of arginines (Arg-73 and Arg-75) as critical residues in these activities. In terms of pairwise sequence, MSAD from Coryneform Bacterium strain FG41 (designated FG41 MSAD) is 38% identical with the Pseudomonas enzyme, including Pro-1 and Asp-37. However, Gln-73 replaces Arg-73, and the second arginine is shifted to Arg-76 by the insertion of a glycine. To determine how these changes relate to the activities of FG41 MSAD, the gene was cloned and the enzyme expressed and characterized. The enzyme has a comparable decarboxylase activity but a significantly reduced hydratase activity. Mutagenesis along with crystal structures of the native enzyme (2.0 Å resolution) and the enzyme modified by a 3-oxopropanoate moiety (resulting from the incubation of the enzyme and 3-bromopropiolate) (2.2 Å resolution) provided a structural basis. The roles of Pro-1 and Asp-37 are likely the same as those proposed for Pp MSAD. However, the side chains of Thr-72, Gln-73, and Tyr-123 replace those of Arg-73 and Arg-75 in the mechanism and play a role in binding and catalysis. The structures also show that Arg-76 is likely too distant to play a direct role in the mechanism. FG41 MSAD is the second functionally annotated homologue in the MSAD family of the tautomerase superfamily and could represent a new subfamily
-
kinetic mutational and structural analysis of malonate semialdehyde decarboxylase from Coryneform Bacterium strain fg41 mechanistic implications for the decarboxylase and hydratase activities
Biochemistry, 2013Co-Authors: Youzhong Guo, Hector Serrano, Gerrit J Poelarends, William H Johnson, Marvin L Hackert, Christian P WhitmanAbstract:Malonate semialdehyde decarboxylase from Pseudomonas pavonaceae 170 (designated Pp MSAD) is in a bacterial catabolic pathway for the nematicide 1,3-dichloropropene. MSAD has two known activities: it catalyzes the metal ion-independent decarboxylation of malonate semialdehyde to produce acetaldehyde and carbon dioxide and a low-level hydration of 2-oxo-3-pentynoate to yield acetopyruvate. The latter activity is not known to be biologically relevant. Previous studies identified Pro-1, Asp-37, and a pair of arginines (Arg-73 and Arg-75) as critical residues in these activities. In terms of pairwise sequence, MSAD from Coryneform Bacterium strain FG41 (designated FG41 MSAD) is 38% identical with the Pseudomonas enzyme, including Pro-1 and Asp-37. However, Gln-73 replaces Arg-73, and the second arginine is shifted to Arg-76 by the insertion of a glycine. To determine how these changes relate to the activities of FG41 MSAD, the gene was cloned and the enzyme expressed and characterized. The enzyme has a comparable decarboxylase activity but a significantly reduced hydratase activity. Mutagenesis along with crystal structures of the native enzyme (2.0 A resolution) and the enzyme modified by a 3-oxopropanoate moiety (resulting from the incubation of the enzyme and 3-bromopropiolate) (2.2 A resolution) provided a structural basis. The roles of Pro-1 and Asp-37 are likely the same as those proposed for Pp MSAD. However, the side chains of Thr-72, Gln-73, and Tyr-123 replace those of Arg-73 and Arg-75 in the mechanism and play a role in binding and catalysis. The structures also show that Arg-76 is likely too distant to play a direct role in the mechanism. FG41 MSAD is the second functionally annotated homologue in the MSAD family of the tautomerase superfamily and could represent a new subfamily.
-
cloning expression and characterization of a cis 3 chloroacrylic acid dehalogenase insights into the mechanistic structural and evolutionary relationship between isomer specific 3 chloroacrylic acid dehalogenases
Biochemistry, 2004Co-Authors: Gerrit J Poelarends, Hector Serrano, William H Johnson, Maria D Person, And Alexey G Murzin, Christian P WhitmanAbstract:The gene encoding the cis-3-chloroacrylic acid dehalogenase (cis-CaaD) from Coryneform Bacterium strain FG41 has been cloned and overexpressed, and the enzyme has been purified to homogeneity and subjected to kinetic and mechanistic characterization. Kinetic studies show that cis-CaaD processes cis-3-haloacrylates, but not trans-3-haloacrylates, with a turnover number of ∼10 s-1. The product of the reaction is malonate semialdehyde, which was confirmed by its characteristic 1H NMR spectrum. The enzyme shares low but significant sequence similarity with the previously studied trans-3-chloroacrylic acid dehalogenase (CaaD) and with other members of the 4-oxalocrotonate tautomerase (4-OT) family. While 4-OT and CaaD function as homo- and heterohexamers, respectively, cis-CaaD appears to be a homotrimeric protein as assessed by gel filtration chromatography. On the basis of the known three-dimensional structures and reaction mechanisms of CaaD and 4-OT, a sequence alignment implicated Pro-1, Arg-70, Arg-73, a...
