title: Overexpression of a recombinant wild-type and His-tagged Bacillus subtilis glycine oxidase in Escherichia coli.
abstract: We have cloned the gene coding for the Bacillus subtilis glycine oxidase (GO), a new flavoprotein that oxidizes glycine and sarcosine to the corresponding alpha-keto acid, ammonia and hydrogen peroxide. By inserting the DNA encoding for GO into the multiple cloning site of the expression vector pT7.7 we produced a recombinant plasmid (pT7-GO). The pT7-GO encodes a fully active fusion protein with six additional residues at the N-terminus of GO (MARIRA). In BL21(DE3)pLysS Escherichia coli cells, and under optimal isopropyl thio-beta-D-galactoside induction conditions, soluble and active chimeric GO was expressed up to 1.14 U g(-1) of cell (and a fermentation yield of 3.82 U x L(-1) of fermentation broth). An N-terminal His-tagged protein (HisGO) was also successfully expressed in E. coli as a soluble protein and a fully active holoenzyme. HisGO represents approximately 3.9% of the total soluble protein content of the cell. The His-tagged GO was purified in a single step by nickel-chelate chromatography to a specific activity of 1.06 U x mg(-1) protein at 25 degrees C and with a yield of 98%. The characterization of the purified enzyme showed that GO is a homotetramer of approximately 180 kDa with the spectral properties typical of flavoproteins. GO exhibits good thermal stability, with a Tm of 46 degrees C after 30 min incubation; its stability is maximal in the 7.0-8.5 pH range. A comparison of amino-acid sequence and substrate specificity indicates that GO has similarities to other flavoenzymes acting on primary amines and on D-amino acids.
authors.affiliation: Department of Structural and Functional Biology, University of Insubria, Varese, Italy.
authors.forename: Viviana
authors.initials: V
authors.lastname: Job
authors.forename: Gianluca
authors.initials: G
authors.lastname: Molla
authors.forename: Mirella S
authors.initials: MS
authors.lastname: Pilone
authors.forename: Loredano
authors.initials: L
authors.lastname: Pollegioni
mesh_terms: D000594:Amino Acid Oxidoreductases / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000201:enzymology*; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000096:biosynthesis*; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
chemical_list: D011994:Recombinant Proteins; D000594:Amino Acid Oxidoreductases; C115925:glycine oxidase