title: Cloning, expression, and transcription analysis of L-arabinose isomerase gene from Mycobacterium smegmatis SMDU.
abstract: The L-arabinose metabolic gene cluster, araA, araB, araD, araG, araH and araR, encoding L-arabinose isomerase (L-AI) and its accessory proteins was cloned from Mycobacterium smegmatis SMDU and sequenced. The deduced amino acid sequence of araA displayed highest identity with that of Bacillus subtilis (52%). These six genes comprised the L-arabinose operon, and its genetic arrangement was similar to that of B. subtilis. The L-AI gene (araA), encoding a 501 amino acid protein with a calculated molecular mass of 54,888 Da, was expressed in Escherichia coli. The productivity and overall enzymatic properties of the recombinant L-AI were almost same as the authentic L-AI from M. smegmatis. Although the recombinant L-AI showed high substrate specificity, as did L-AI from other organisms, this enzyme catalyzed not only isomerization of L-arabinose-L-ribulose and D-galactose-D-tagatose but also isomerization of L-altrose-L-psicose and L-erythrulose-L-threose. In combination with L-AI from M. smegmatis, L-threose and L-altrose can be produced from cheap and abundant erythritol and D-fructose respectively, indicating that this enzyme has great potential for biological application in rare sugar production. Transcription analysis using various sugars revealed that this enzyme was significantly induced not only by L-arabinose and D-galactose but also by L-ribose, galactitol, L-ribulose, and L-talitol. This different result of transcription mediated by sugars from that of E. coli suggests that the transcriptional regulation of araA from M. smegmatis against sugar is loose compared with that from E. coli, and that it depends on the hydroxyl configuration at C2, C3 and C4 positions of sugars.
authors: Rare Sugar Research Center, Kagawa University, Miki, Kagawa, Japan. goro@rare-sugar.com
authors: Goro
authors: G
authors: Takata
authors: Wayoon
authors: W
authors: Poonperm
authors: Devendar
authors: D
authors: Rao
authors: Akane
authors: A
authors: Souda
authors: Tomoe
authors: T
authors: Nishizaki
authors: Kenji
authors: K
authors: Morimoto
authors: Ken
authors: K
authors: Izumori
mesh_terms: D019747:Aldose-Ketose Isomerases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D001089:Arabinose; D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D001483:Base Sequence; D002384:Catalysis; D003001:Cloning, Molecular; D004187:Disaccharides / Q000737:chemistry; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D007536:Isomerism; D008969:Molecular Sequence Data; D020102:Mycobacterium smegmatis / Q000201:enzymology*; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D004187:Disaccharides; D011994:Recombinant Proteins; D001089:Arabinose; D019747:Aldose-Ketose Isomerases; C019715:L-arabinose isomerase