title: Enzymes of a new modified ortho-pathway utilizing 2-chlorophenol in Rhodococcus opacus 1CP.
abstract: Chlorocatechol 1,2-dioxygenase (CC 1,2-DO), chloromuconate cycloisomerase (CMCI), chloromuconolactone isomerase (CMLI), and dienolactone hydrolase (DELH), the key enzymes of a new modified ortho-pathway in Rhodococcus opacus 1CP cells utilizing 2-chlorophenol via a 3-chlorocatechol branch of a modified ortho-pathway, were isolated and characterized. CC 1,2-DO showed the maximum activity with 3-chlorocatechol; its activity with catechol and 4-chlorocatechol was 93 and 50%, respectively. The enzyme of the studied pathway had physicochemical properties intermediate between the pyrocatechase of ordinary and chlorocatechase of modified pathways described earlier for this strain. In contrast to the enzymes investigated earlier, CMCI of the new pathway exhibited high substrate specificity. The enzyme had Km for 2-chloromuconate of 142.86 microM, Vmax = 71.43 U/mg, pH optimum around 6.0, and temperature optimum at 65 degrees C. CMCI converted 2-chloromuconate into 5-chloromuconolactone. CMLI converted 5-chloromuconolactone into cis-dienolactone used as a substrate by DELH; this enzyme did not convert trans-dienolactone. DELH had Km for cis-dienolactone of 200 microM, Vmax = 167 U/mg, pH optimum of 8.6, and temperature optimum of 40 degrees C. These results confirm the existence of a new modified ortho-pathway for utilization of 2-chlorophenol by R. opacus 1CP.
authors.affiliation: Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia. Golovleva@ibpm.serpukhov.su
authors.forename: O V
authors.initials: OV
authors.lastname: Moiseeva
authors.forename: O V
authors.initials: OV
authors.lastname: Belova
authors.forename: I P
authors.initials: IP
authors.lastname: Solyanikova
authors.forename: M
authors.initials: M
authors.lastname: Schlömann
authors.forename: L A
authors.initials: LA
authors.lastname: Golovleva
mesh_terms: D001426:Bacterial Proteins; D019748:Carbon-Carbon Double Bond Isomerases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002396:Catechols / Q000378:metabolism*; D002733:Chlorophenols / Q000378:metabolism*; D049308:Dioxygenases; D004591:Electrophoresis, Polyacrylamide Gel; D006867:Hydrolases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D019753:Intramolecular Lyases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D015394:Molecular Structure; D010105:Oxygenases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D012240:Rhodococcus / Q000201:enzymology* / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet
chemical_list: D001426:Bacterial Proteins; D002396:Catechols; D002733:Chlorophenols; C031137:3-chlorocatechol; D010105:Oxygenases; D049308:Dioxygenases; C044173:chlorocatechol 1,2-dioxygenase; D006867:Hydrolases; D019748:Carbon-Carbon Double Bond Isomerases; C100087:muconolactone delta-isomerase; D019753:Intramolecular Lyases; C055773:chloromuconate cycloisomerase; C030683:2-chlorophenol