Characterization of NADP+-specific l-rhamnose dehydrogenase from the thermoacidophilic Archaeon Thermoplasma acidophilum

• Published in: Extremophiles : life under extreme conditions Vol. 16; no. 3; pp. 447 - 454
• Main Authors: Kim, Suk Min, Paek, Kwang Hyun, Lee, Sun Bok
• Format: Journal Article
• Language: English
• Published: Japan Springer Japan 01.05.2012; Springer
• Subjects: Animal, plant and microbial ecology; Archaeal Proteins - chemistry; Archaeal Proteins - genetics; Archaeal Proteins - metabolism; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Biochemistry; Biological and medical sciences; Biomedical and Life Sciences; Biotechnology; Carbohydrate Dehydrogenases - chemistry; Carbohydrate Dehydrogenases - genetics; Carbohydrate Dehydrogenases - metabolism; Escherichia coli - genetics; Escherichia coli - metabolism; Fundamental and applied biological sciences. Psychology; Gene Expression; Life Sciences; Microbial Ecology; Microbiology; NADP - chemistry; NADP - genetics; NADP - metabolism; Original Paper; Phylogeny; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Rhamnose - chemistry; Rhamnose - genetics; Rhamnose - metabolism; Thermoplasma - enzymology; Thermoplasma - genetics; NADP-specific; Thermophilic enzyme; rhamnose dehydrogenase; Non-phosphorylated pathway; Archaea; Acidophily; Phosphorylation; Enzyme; Archaeobacteria; Thermophily; Thermoplasma acidophilum; L-rhamnose dehydrogenase; L-Rhamnose 1-dehydrogenase; Characterization; Bacteria; Oxidoreductases; Extreme environment
• ISSN: 1431-0651; 1433-4909; 1433-4909
• DOI: 10.1007/s00792-012-0444-1

Thermoplasma acidophilum utilizes l -rhamnose as a sole carbon source. To determine the metabolic pathway of l -rhamnose in Archaea, we identified and characterized l -rhamnose dehydrogenase (RhaD) in T. acidophilum . Ta0747P gene, which encodes the putative T. acidophilum RhaD (Ta_RhaD) enzyme belonging to the short-chain dehydrogenase/reductase family, was expressed in E. coli as an active enzyme catalyzing the oxidation of l -rhamnose to l -rhamnono-1,4-lactone. Analysis of catalytic properties revealed that Ta_RhaD oxidized l -rhamnose, l -lyxose, and l -mannose using only NADP + as a cofactor, which is different from NAD + /NADP + -specific bacterial RhaDs and NAD + -specific eukaryal RhaDs. Ta_RhaD showed the highest activity toward l -rhamnose at 60 °C and pH 7. The K m and k cat values were 0.46 mM, 1,341.3 min −1 for l -rhamnose and 0.1 mM, 1,027.2 min −1 for NADP + , respectively. Phylogenetic analysis indicated that branched lineages of archaeal RhaD are quite distinct from those of Bacteria and Eukarya. This is the first report on the identification and characterization of NADP + -specific RhaD.