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Methylcatechol 1,2-Dioxygenase of Rhodococcus opacus 6a Is a New Type of the Catechol-Cleaving Enzyme

I. P. Solyanikova1, E. I. Konovalova1,2, and L. A. Golovleva1,2*

1Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, pr. Nauki 5, 142290 Pushchino, Moscow Region, Russia; E-mail: golovleva@ibpm.pushchino.ru

2Pushchino State University, pr. Nauki 3, 142290 Pushchino, Moscow Region, Russia

* To whom correspondence should be addressed.

Received March 5, 2009; Revision received April 1, 2009
The strains Rhodococcus sp. 400, R. rhodochrous 172, and R. opacus 6a utilize 4-methylbenzoate as the only carbon and energy source. 4-Methylcatechol is a key intermediate of biodegradation. Its further conversion by all the strains proceeds via ortho-cleavage. The specific activity of catechol 1,2-dioxygenase assayed in crude extracts of Rhodococcus sp. 400 and R. rhodochrous 172 with 3- and 4-methylcatechols does not exceed the enzyme activity assayed with catechol. Two catechol 1,2-dioxygenases have been purified from the biomass of R. opacus strain 6a grown with 4-methylbenzoate. These enzymes differed in molecular mass and physicochemical and catalytic properties. One of these enzymes belongs to the type of enzymes cleaving the catechol ring and known as methylcatechol 1,2-dioxygenases. In bacteria of the Rhodococcus genus, such an enzyme is described here for the first time.
KEY WORDS: para-toluate, degradation, methylcatechol 1,2-dioxygenase, Rhodococcus opacus 6a

DOI: 10.1134/S0006297909090077