tailieunhanh - Báo cáo khoa học: The role of residue Thr249 in modulating the catalytic efficiency and substrate specificity of catechol-2,3-dioxygenase from Pseudomonas stutzeri OX1

Bioremediation strategies use microorganisms to remove hazardous sub-stances, such as aromatic molecules, from polluted sites. The applicability of these techniques would greatly benefit from the expansion of the cata-bolic ability of these bacteria in transforming a variety of aromatic com-pounds. | ềFEBS Journal The role of residue Thr249 in modulating the catalytic efficiency and substrate specificity of catechol-2 3-dioxygenase from Pseudomonas stutzeri OX1 Loredana Siani1 z Ambra Viggiani1 z Eugenio Notomista1 Alessandro Pezzella2 and Alberto Di Donato1 1 Dipartimento di Biologia Strutturale e Funzionale University di Napoli Federico II Napoli and CEINGE-Biotecnologie Avanzate . Italy 2 Dipartimento di Chimica Organica e Biochimica University di Napoli Federico II Italy Keywords bioremediation dioxygenase enzyme kinetics protein expression Pseudomonas stutzeri Correspondence A. Di Donato Dipartimento di Biologia Strutturale e Funzionale Universita di Napoli Federico II Via Cinthia I-80126 Napoli Italy Fax 39 081 676710 Tel 39 081 679143 E-mail didonato@ These authors contributed equally to this work Received 27 January 2006 revised 28 March 2006 accepted 4 May 2006 doi Bioremediation strategies use microorganisms to remove hazardous substances such as aromatic molecules from polluted sites. The applicability of these techniques would greatly benefit from the expansion of the catabolic ability of these bacteria in transforming a variety of aromatic compounds. Catechol-2 3-dioxygenase C2 3O from Pseudomonas stutzeri OX1 is a key enzyme in the catabolic pathway for aromatic molecules. Its specificity and regioselectivity control the range of molecules degraded through the catabolic pathway of the microorganism that is able to use aromatic hydrocarbons as growth substrates. We have used in silico substrate docking procedures to investigate the molecular determinants that direct the enzyme substrate specificity. In particular we looked for a possible molecular explanation of the inability of catechol-2 3-dioxygenase to cleave 3 5-dimethylcatechol and 3 6-dimethylcatechol and of the efficient cleavage of 3 4-dimethylcatechol. The docking study suggested that reduction in the volume of the side chain of residue 249