High yields of active Thermus thermophilus proline dehydrogenase are obtained using maltose-binding protein as a solubility tag

Biotechnol J. 2015 Mar;10(3):395-403. doi: 10.1002/biot.201400229. Epub 2015 Jan 19.


Proline dehydrogenase (ProDH) catalyzes the FAD-dependent oxidation of proline to Δ(1) -pyrroline-5-carboxylate, the first step of proline catabolism in many organisms. Next to being involved in a number of physiological processes, ProDH is of interest for practical applications because the proline imino acid can serve as a building block for a wide range of peptides and antibiotics. ProDH is a membrane-associated protein and recombinant soluble forms of the enzyme have only been obtained in limited amounts. We here report on the heterologous production of ProDH from Thermus thermophilus (TtProDH) in Escherichia coli. Using maltose-binding protein as solubility tag, high yields of active holoenzyme are obtained. Native TtProDH can be produced from cleaving the purified fusion protein with trypsin. Size-exclusion chromatography shows that fused and clipped TtProDH form oligomers. Thermal stability and co-solvent tolerance indicate the conformational robustness of TtProDH. These properties together with the high yield make TtProDH attractive for industrial applications.

Keywords: Flavoenzyme; Maltose-binding protein; Proline dehydrogenase; Protein stability; Solubility tag.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / isolation & purification*
  • Bacterial Proteins / metabolism
  • Chromatography, Gel / methods
  • Enzyme Stability
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Maltose-Binding Proteins / metabolism*
  • Models, Molecular
  • Proline Oxidase / chemistry
  • Proline Oxidase / genetics
  • Proline Oxidase / isolation & purification*
  • Proline Oxidase / metabolism
  • Protein Conformation
  • Solubility
  • Temperature
  • Thermus thermophilus / enzymology*


  • Bacterial Proteins
  • Maltose-Binding Proteins
  • Proline Oxidase