Enzymological characteristics of a novel archaeal dye-linked d-lactate dehydrogenase showing loose binding of FAD

• Published in: Extremophiles : life under extreme conditions 2018-11, Vol.22 (6), p.975-981
• Main Authors: Satomura, Takenori, Hayashi, Junji, Ohshida, Tatsuya, Sakuraba, Haruhiko, Ohshima, Toshihisa, Suye, Shin-ichiro
• Format: Article
• Language: English
• Subjects: Amino acid sequence; Amino acid sequences; Amino acids; Archaea; Binding; Biochemistry; Biomedical and Life Sciences; Biotechnology; D-Lactate dehydrogenase; Dehydrogenase; Dehydrogenases; DNA; Dyes; E coli; Enzymatic activity; Enzyme activity; Enzymology; Escherichia coli; Flavin-adenine dinucleotide; Genomes; Homology; Hyperthermophilic archaea; Identification; L-Lactate dehydrogenase; Lactate; Lactate dehydrogenase; Lactic acid; Life Sciences; Microbial Ecology; Microbiology; Original Paper; Proteins; Recombinants; Space life sciences; Thermoproteus tenax
• ISSN: 1431-0651; 1433-4909
• DOI: 10.1007/s00792-018-1054-3

A gene-encoding a dye-linked d -lactate dehydrogenase (Dye-DLDH) homolog was identified in the genome of the hyperthermophilic archaeon Thermoproteus tenax . The gene was expressed in Escherichia coli and the product was purified to homogeneity. The recombinant protein exhibited highly thermostable Dye-DLDH activity. To date, four types of Dye-DLDH have been identified in hyperthermophilic archaea (in Aeropyrum pernix , Sulfolobus tokodaii , Archaeoglobus fulgidus , and Candidatus Caldiarchaeum subterraneum). The amino acid sequence of T. tenax Dye-DLDH showed the highest similarity (45%) to A. pernix Dye-DLDH, but neither contained a known FAD-binding motif. Nonetheless, both homologs required FAD for enzymatic activity, suggesting that FAD binds loosely to the enzyme and is easily released unlike in other Dye-DLDHs. Our findings indicate that Dye-DLDHs from T. tenax and A. pernix are a novel type of Dye-DLDH characterized by loose binding of FAD.