Characterization of the Maleylacetate Reductase MacA of Rhodococcus opacus 1CP and Evidence for the Presence of an Isofunctional Enzyme
AUTOR(ES)
Seibert, Volker
FONTE
American Society for Microbiology
RESUMO
Maleylacetate reductases (EC 1.3.1.32) have been shown to contribute not only to the bacterial catabolism of some usual aromatic compounds like quinol or resorcinol but also to the degradation of aromatic compounds carrying unusual substituents, such as halogen atoms or nitro groups. Genes coding for maleylacetate reductases so far have been analyzed mainly in chloroaromatic compound-utilizing proteobacteria, in which they were found to belong to specialized gene clusters for the turnover of chlorocatechols or 5-chlorohydroxyquinol. We have now cloned the gene macA, which codes for one of apparently (at least) two maleylacetate reductases in the gram-positive, chlorophenol-degrading strain Rhodococcus opacus 1CP. Sequencing of macA showed the gene product to be relatively distantly related to its proteobacterial counterparts (ca. 42 to 44% identical positions). Nevertheless, like the known enzymes from proteobacteria, the cloned Rhodococcus maleylacetate reductase was able to convert 2-chloromaleylacetate, an intermediate in the degradation of dichloroaromatic compounds, relatively fast and with reductive dehalogenation to maleylacetate. Among the genes ca. 3 kb up- and downstream of macA, none was found to code for an intradiol dioxygenase, a cycloisomerase, or a dienelactone hydrolase. Instead, the only gene which is likely to be cotranscribed with macA encodes a protein of the short-chain dehydrogenase/reductase family. Thus, the R. opacus maleylacetate reductase gene macA clearly is not part of a specialized chlorocatechol gene cluster.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=107314Documentos Relacionados
- Conversion of 2-Fluoromuconate to cis-Dienelactone by Purified Enzymes of Rhodococcus opacus 1cp
- Identification of Fluoropyrogallols as New Intermediates in Biotransformation of Monofluorophenols in Rhodococcus opacus 1cp
- Characterization of a Protocatechuate Catabolic Gene Cluster from Rhodococcus opacus 1CP: Evidence for a Merged Enzyme with 4-Carboxymuconolactone-Decarboxylating and 3-Oxoadipate Enol-Lactone-Hydrolyzing Activity
- Evolutionary Relationship between Chlorocatechol Catabolic Enzymes from Rhodococcus opacus 1CP and Their Counterparts in Proteobacteria: Sequence Divergence and Functional Convergence
- A New Modified ortho Cleavage Pathway of 3-Chlorocatechol Degradation by Rhodococcus opacus 1CP: Genetic and Biochemical Evidence