Characterization of an L-arabinose isomerase from Bacillus subtilis.
An isolated gene from Bacillus subtilis str. 168 encoding a putative isomerase was proposed as an L-arabinose isomerase (L-AI), cloned into Escherichia coli, and its nucleotide sequence was determined. DNA sequence analysis revealed an open reading frame of 1,491 bp, capable of encoding a polypeptide of 496 amino acid residues. The gene was overexpressed in E. coli and the protein was purified using nickel-nitrilotriacetic acid chromatography. The purified enzyme showed the highest catalytic efficiency ever reported, with a k(cat) of 14,504 min(-1) and a k(cat)/K(m) of 121 min(-1) mM(-1) for L-arabinose. A homology model of B. subtilis L-AI was constructed based on the X-ray crystal structure of E. coli L-AI. Molecular dynamics simulation studies of the enzyme with the natural substrate, L-arabinose, and an analogue, D-galactose, shed light on the unique substrate specificity displayed by B. subtilis L-AI only towards L-arabinose. Although L-AIs have been characterized from several other sources, B. subtilis L-AI is distinguished from other L-AIs by its high substrate specificity and catalytic efficiency for L-arabinose.
Kim
Jin-Ha
JH
BioNgene Co. Ltd., 10-1 Myungryun-Dong, Jongro-Gu, Seoul, 110521, Korea.
Prabhu
Ponnandy
P
Jeya
Marimuthu
M
Tiwari
Manish Kumar
MK
Moon
Hee-Jung
HJ
Singh
Raushan Kumar
RK
Lee
Jung-Kul
JK
D019747:Aldose-Ketose Isomerases / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics; D001089:Arabinose / Q000737:chemistry* / Q000378:metabolism; D001412:Bacillus subtilis / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D001483:Base Sequence; D003001:Cloning, Molecular; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D013379:Substrate Specificity
D011994:Recombinant Proteins; D001089:Arabinose; D019747:Aldose-Ketose Isomerases