title: Correlation of thermostability and conformational changes of catechol 2, 3-dioxygenases from two disparate micro-organisms.
abstract: We have investigated the structure of recombinant catechol 2, 3-dioxygenase (C23O) purified from two species in which the enzyme has evolved to function at different temperature. The two species are mesophilic bacterium Pseudomonas putida strain mt-2 and thermophilic archaea Sulfolobus acidocaldariusDSM639. Using the primary sequence analysis, we show that both C23Os have only 30% identity and 48% similarity but contain conserved amino acid residues forming an active site area around the iron ion. The corresponding differences in homology, but structural similarity in active area residues, appear to provide completely different responses to heating the two enzymes. We confirm this by small angle X-ray scattering and demonstrate that the overall structure of C23O from P. putida is slightly different from its crystalline form whereas the solution scattering of C23O from S. acidocaldarius at temperatures between 4 and 85°C ideally fits the calculated scattering from the single crystal structure. The thermostability of C23O from S. acidocaldarius correlates well with conformation in solution during thermal treatment. The similarity of the two enzymes in primary and tertiary structure may be taken as a confirmation that two enzymes have evolved from a common ancestor.
authors.affiliation: Bragg Institute, ANSTO, Locked Bag 2001, Kirrawee DC, NSW, 2232 Australia. Electronic address: anna.sokolova@ansto.gov.au.
authors.forename: Anna
authors.initials: A
authors.lastname: Sokolova
authors.forename: Shir-Ly
authors.initials: SL
authors.lastname: Huang
authors.forename: Anthony
authors.initials: A
authors.lastname: Duff
authors.forename: Elliot Paul
authors.initials: EP
authors.lastname: Gilbert
authors.forename: Wen-Hsien
authors.initials: WH
authors.lastname: Li
mesh_terms: D000595:Amino Acid Sequence; D020134:Catalytic Domain; D050557:Catechol 2,3-Dioxygenase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D055550:Protein Stability; D017434:Protein Structure, Tertiary; D016958:Pseudomonas putida / Q000201:enzymology*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D053838:Scattering, Small Angle; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D016945:Sulfolobus acidocaldarius / Q000201:enzymology*; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D011994:Recombinant Proteins; D050557:Catechol 2,3-Dioxygenase
keywords: Catechol 2, 3-dioxygenase; Modelling; Protein structure; Small angle X-ray scattering; Thermal effect