Borneol Dehydrogenase from Pseudomonas sp. Strain TCU-HL1 Catalyzes the Oxidation of (+)-Borneol and Its Isomers to Camphor.

ABSTRACT: Most plant-produced monoterpenes can be degraded by soil microorganisms. Borneol is a plant terpene that is widely used in traditional Chinese medicine. Neither microbial borneol dehydrogenase (BDH) nor a microbial borneol degradation pathway has been reported previously. One borneol-degrading strain, Pseudomonas sp. strain TCU-HL1, was isolated by our group. Its genome was sequenced and annotated. The genome of TCU-HL1 consists of a 6.2-Mbp circular chromosome and one circular plasmid, pTHL1 (12.6 kbp). Our results suggest that borneol is first converted into camphor by BDH in TCU-HL1 and is further decomposed through a camphor degradation pathway. The recombinant BDH was produced in the form of inclusion bodies. The apparent K_m values of refolded recombinant BDH for (+)-borneol and (-)-borneol were 0.20 ± 0.01 and 0.16 ± 0.01 mM, respectively, and the k_cat values for (+)-borneol and (-)-borneol were 0.75 ± 0.01 and 0.53 ± 0.01 s^-1, respectively. Two plant BDH genes have been reported previously. The k_cat and k_cat/K_m values of lavender BDH are about 1,800-fold and 500-fold lower, respectively, than those of TCU-HL1 BDH.

Importance

The degradation of borneol in a soil microorganism through a camphor degradation pathway is reported in this study. We also report a microbial borneol dehydrogenase. The k_cat and k_cat/K_m values of lavender BDH are about 1,800-fold and 500-fold lower, respectively, than those of TCU-HL1 BDH. The indigenous borneol- and camphor-degrading strain isolated, Pseudomonas sp. strain TCU-HL1, reminds us of the time 100 years ago when Taiwan was the major producer of natural camphor in the world.

SUBMITTER: Tsang HL 

PROVIDER: S-EPMC5066354 | biostudies-literature | 2016 Nov

REPOSITORIES: biostudies-literature