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Pohlenz HD,
Boidol W,
Schüttke I,
Streber WR,
( 1992 ) Purification and properties of an Arthrobacter oxydans P52 carbamate hydrolase specific for the herbicide phenmedipham and nucleotide sequence of the corresponding gene. PMID : 1400211 : DOI : 10.1128/jb.174.20.6600-6607.1992 PMC : PMC207632 Abstract >>
Arthrobacter oxydans P52 isolated from soil samples was found to degrade the phenylcarbamate herbicides phenmedipham and desmedipham cometabolically by hydrolyzing their central carbamate linkages. The phenylcarbamate hydrolase (phenmedipham hydrolase) responsible for the degradative reaction was purified to homogeneity. The enzyme was shown to be a monomer with a molecular weight of 55,000. A 41-kb wild-type plasmid (pHP52) was identified in A. oxydans P52, but not in a derivative of this strain that had spontaneously lost the ability to hydrolyze phenylcarbamates, indicating that the gene for phenylcarbamate degradation (pcd) is plasmid encoded. Determination of two partial amino acid sequences allowed the localization of the coding sequence of the pcd gene on a 3.3-kb PstI restriction fragment within pHP52 DNA by hybridization with synthetic oligonucleotides. The phenylcarbamate hydrolase was functionally expressed in Escherichia coli under control of the lacZ promoter after the 3.3-kb PstI fragment was subcloned into the vector pUC19. A stretch of 1,864 bases within the cloned Pst fragment was sequenced. Sequence analysis revealed an open reading frame of 1,479 bases containing the amino acid partial sequences determined for the purified enzyme. Sequence comparisons revealed significant homology between the pcd gene product and the amino acid sequences of esterases of eukaryotic origin. Subsequently, it was demonstrated that the esterase substrate p-nitrophenylbutyrate is hydrolyzed by phenmedipham hydrolase.
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2. |
Mauch L,
Bichler V,
Brandsch R,
( 1990 ) Lysine can replace arginine 67 in the mediation of covalent attachment of FAD to histidine 71 of 6-hydroxy-D-nicotine oxidase. PMID : 2115879 : Abstract >>
The requirements for FAD-attachment to His71 of 6-hydroxy-D-nicotine oxidase (6-HDNO) were investigated by site-directed mutagenesis. The following amino acid replacements were introduced into the sequence Arg67-Ser68-Gly69-Gly70-His71 of the 6-HDNO-polypeptide: 1) Arg67 was replaced with Ala (A1 mutant); 2) Ser68 was replaced with Ala (A2 mutant); and 3) Arg67 was replaced with Lys (K mutant). The substitution in mutant A2 had no effect on flavinylation, measured as [14C]FAD incorporation into apo-6-HDNO. Replacement of Arg67 with Ala prevented, but replacement with Lys permitted the flavinylation of His71. Mutant A1 showed no 6-HDNO activity, whereas the replacement of Ser with Ala in mutant A2 had only a slight effect on 6-HDNO activity. The substitution of Lys for Arg67, however, reduced the specific 6-HDNO activity in extracts of Escherichia coli cells expressing the mutant polypeptide from 50.3 to 17.5 milliunits/mg protein. It is concluded that a basic amino acid residue (Arg67 or Lys67) is required to mediate the attachment of FAD to His71, and while Lys can substitute for Arg67 in this function, it can only partially replace Arg67 in the enzyme reaction mechanism of 6-HDNO.
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3. |
Kim YM,
Ko EA,
Kang HK,
Kim D,
( 2009 ) Construction, expression and characterization of fusion enzyme from Arthrobacter oxydans dextranase and Klebsiella pneumoniae amylase. PMID : 19305953 : DOI : 10.1007/s10529-009-9967-7 Abstract >>
An artificial fusion protein of Arthrobacter oxydans dextranase and Klebsiella pneumoniae alpha-amylase was constructed and expressed in Escherichia coli. Most of the expressed protein existed as an insoluble fraction, which was solubilized with urea. The purified fusion enzyme electrophoretically migrated as a single protein band; M = 137 kDa, and exhibited activities of both dextranase (10.8 U mg(-1)) and amylase (7.1 U mg(-1)), which were lower than that of reference dextranase (13.3 U mg(-1)) and alpha-amylase (103 U mg(-1)). The fusion enzyme displayed bifunctional enzyme activity at pH 5-7 at 37 degrees C. These attributes potentially make the fusion enzyme more convenient for use in sugar processing than a two-enzyme system.
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4. |
Navarro-Llorens JM,
Drzyzga O,
Perera J,
( 2008 ) Genetic analysis of phenylacetic acid catabolism in Arthrobacter oxydans CECT386. PMID : 18437357 : DOI : 10.1007/s00203-008-0370-x Abstract >>
Arthrobacter oxydans CECT386 is a Gram-positive bacterium able to use either phenylacetic acid or phenylacetaldehyde as the sole carbon and energy source for aerobic growth. Genes responsible for the catabolism of these compounds have been located at two chromosomal regions and were organized in one isolated paaN gene and two putative paa operons, one consisting of the paaD, paaF, tetR and prot genes, and one consisting of the paaG, paaH, paaI, paaJ, paaK and paaB genes. The identity of the paaF and paaN genes was supported by functional complementation experiments. A comparison with the paa catabolic genes and/or gene clusters of other bacteria that degrade these aromatic compounds is presented. The results of this study broaden the knowledge regarding the range of metabolic potential of this strain and eventually make it attractive for environmental applications.
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5. |
Mauch L,
Bichler V,
Brandsch R,
( 1989 ) Site-directed mutagenesis of the FAD-binding histidine of 6-hydroxy-D-nicotine oxidase. Consequences on flavinylation and enzyme activity. PMID : 2680607 : DOI : 10.1016/0014-5793(89)81792-2 Abstract >>
In 6-hydroxy-D-nicotine oxidase (6-HDNO) FAD is covalently bound to His71 of the polypeptide chain by an 8 alpha-(N3-histidyl)-riboflavin linkage. The FAD-binding histidine was exchanged by site-directed mutagenesis to either a Cys- or Tyr-residue, two amino acids known to be involved in covalent binding of FAD in other enzymes, or to a Ser-residue. None of the amino acid replacements for His71 allowed covalent FAD incorporation into the 6-HDNO polypeptide. Thus, the amino acid residues involved in covalent FAD-binding require a specific polypeptide surrounding in order for this modification to proceed and cannot be replaced with each other. Enzyme activity was completely abolished with Tyr in place of His71. 6-HDNO activity with non-covalently bound FAD was found with 6-HDNO-Cys and to a lesser extent also with 6-HDNO-Ser. However, the Km values for 6-HDNO-Cys and 6-HDNO-Ser were increased approximately 20-fold as compared to 6-HDNO-His. Both mutant enzymes, in contrast to the wild-type enzyme, needed additional FAD in the enzymatic assay (50 microM for 6-HDNO-Ser and 10 microM for 6-HDNO-Cys) for maximal enzyme activity.
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6. |
Brandsch R,
Bichler V,
Nagursky H,
( 1987 ) Covalent flavinylation of 6-hydroxy-D-nicotine oxidase analyzed by partial deletions of the gene. PMID : 3036509 : DOI : 10.1111/j.1432-1033.1987.tb11476.x Abstract >>
The expression of the enzymatically active 6-hydroxy-D-nicotine oxidase (6-HDNO) from Arthrobacter oxidans requires the covalent attachment of FAD to the polypeptide chain. How this modification takes place and at what time during the synthesis of the polypeptide is not known. We investigated the possibility of cotranslational flavinylation by generating various deletions of the 6-HDNO gene carried on appropriate plasmid vectors. The polypeptides expressed from these plasmids were analyzed for their ability to incorporate [14C]FAD covalently in an Escherichia coli-derived coupled transcription/translation system. The data show that removal of approximately 40% from the carboxy-terminal part of the 6-HDNO polypeptide did not inhibit the covalent flavinylation of the truncated protein. A fusion protein, consisting of the truncated 6-HDNO polypeptide and the beta-lactamase of pBR322, was also covalently flavinylated. The amino acid sequence surrounding the histidine residue, assumed to bind FAD, was shown to be situated approximately 70 amino acid residues from the amino-terminal end of the 6-HDNO polypeptide. Removal of the first 30 amino acids did not abolish covalent flavinylation. Flavinylation could no longer be detected, however, if a short amino acid sequence, consisting of seven residues, replaced the amino acid sequence upstream of the histidine. These findings prove, in our opinion, that cotranslational flavinylation takes place in the synthesis of 6-HDNO.
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7. |
Brandsch R,
Hinkkanen AE,
Mauch L,
Nagursky H,
Decker K,
( 1987 ) 6-Hydroxy-D-nicotine oxidase of Arthrobacter oxidans. Gene structure of the flavoenzyme and its relationship to 6-hydroxy-L-nicotine oxidase. PMID : 3622516 : DOI : 10.1111/j.1432-1033.1987.tb13338.x Abstract >>
The nucleotide sequence of the 6-hydroxy-D-nicotine oxidase (6-HDNO) gene of Arthrobacter oxidans is presented. This covalently flavinylated enzyme specifically oxidizes 6-hydroxy-D-nicotine to 6-hydroxy-N-methylmyosmine. Coinduced in the presence of nicotine is a 6-hydroxy-L-nicotine-specific enzyme, 6-hydroxy-L-nicotine oxidase (6-HLNO), with FAD noncovalently bound to the apoprotein. A comparison of the nucleotide-derived amino acid sequence of the 6-HDNO with the amino acid sequence data obtained from the purified 6-HLNO polypeptide suggests that the two enantiozymes expressed within the same cell are genetically unrelated. This conclusion is supported by the finding that the FAD-binding sites of the two enzymes are different. 6-HLNO exhibits at the amino-terminus of the polypeptide chain a dinucleotide-binding site characteristic for many other FAD- and NAD(P)-dependent enzymes. No such sequence was found in the nucleotide-derived amino acid sequence of 6-HDNO.
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