Identification of a gene cluster associated with triclosan catabolism

Abstract

Aerobic degradation of bis-aryl ethers like the antimicrobial triclosan typically proceeds through oxygenase-dependent catabolic pathways. Although several studies have reported on bacteria capable of degrading triclosan aerobically, there are no reports describing the genes responsible for this process. In this study, a gene encoding the large subunit of a putative triclosan oxygenase, designated tcsA was identified in a triclosan-degrading fosmid clone from a DNA library of Sphingomonas sp. RD1. Consistent with tcsA's similarity to two-part dioxygenases, a putative FMN-dependent ferredoxin reductase, designated tcsB was found immediately downstream of tcsA. Both tcsAB were found in the midst of a putative chlorocatechol degradation operon. We show that RD1 produces hydroxytriclosan and chlorocatechols during triclosan degradation and that tcsA is induced by triclosan. This is the first study to report on the genetics of triclosan degradation.

Triclosan Dioxygenase: A Novel Two-component Rieske Nonheme Iron Ring-hydroxylating Dioxygenase Initiates Triclosan Degradation

“…E. coli BL21(DE3) containing the recombinant plasmid pETDuet-tcsAB coexpressing TcsAB was able to convert 0.1 mM TCS to 0.05 mM 2,4-DCP within 9 h (Figure 1B), supporting previous findings on the conversion of TCS by the TcsAB of strain RD1. 21 P. knackmussii B13 was used as another host for the heterologous expression of tcsAB. The genome of strain B13 lacks the tcsAB and tfdB genes; thus, strain B13 cannot utilize TCS as the sole carbon source for degradation and growth.…”

“…17,20 Additionally, the known TCSdegrading bacteria that are capable of complete mineralization are not amenable to genetic manipulation, which has limited our understanding of the specific metabolic mechanisms of TCS. 21 Therefore, further in-depth study of the molecular mechanisms of TCS degradation is crucial for enhancing our understanding and providing valuable guidance for TCS bioremediation.…”

Degradation of Triclosan in the Water Environment by Microorganisms: A Review

“…As for the studies of specific functional enzymes, a novel TCS oxygenase TcsA was the only biochemically identified protein responsible for TCS biodegradation [103]. Gene tcsA encoding the putative TCS oxygenase large subunit was identified in a TCS-degrading fosmid clone from the DNA library of Sphingomonas sp.…”

“…Gene tcsA encoding the putative TCS oxygenase large subunit was identified in a TCS-degrading fosmid clone from the DNA library of Sphingomonas sp. RD1 [103]. Hydroxy-TCS and chlorocatechols were produced during TCS biodegradation by strain RD1, and TcsA was induced by TCS [103].…”

“…RD1 [103]. Hydroxy-TCS and chlorocatechols were produced during TCS biodegradation by strain RD1, and TcsA was induced by TCS [103]. BLASTp analysis revealed that the best match to TcsA was that of the Rieske [2Fe-2S] cluster domain-containing protein from Sphingopyxis sp.…”