Caffeine junkie: An unprecedented glutathione S-transferase-dependent oxygenase required for caffeine degradation by pseudomonas putida CBB5

Ryan M. Summers, Jennifer L. Seffernick, Erik M. Quandt, Chi Li Yu, Jeffrey E. Barrick, Mani V. Subramanian

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

Caffeine and other N-methylated xanthines are natural products found in many foods, beverages, and pharmaceuticals. Therefore, it is not surprising that bacteria have evolved to live on caffeine as a sole carbon and nitrogen source. The caffeine degradation pathway of Pseudomonas putida CBB5 utilizes an unprecedented glutathione-S-transferase-dependent Rieske oxygenase for demethylation of 7-methylxanthine to xanthine, the final step in caffeine N-demethylation. The gene coding this function is unusual, in that the iron-sulfur and non-heme iron domains that compose the normally functional Rieske oxygenase (RO) are encoded by separate proteins. The non-heme iron domain is located in the monooxygenase, ndmC, while the Rieske [2Fe-2S] domain is fused to the RO reductase gene, ndmD. This fusion, however, does not interfere with the interaction of the reductase with N1- and N3-demethylase RO oxygenases, which are involved in the initial reactions of caffeine degradation. We demonstrate that the N7-demethylation reaction absolutely requires a unique, tightly bound protein complex composed of NdmC, NdmD, and NdmE, a novel glutathione-S-transferase (GST). NdmE is proposed to function as a noncatalytic subunit that serves a structural role in the complexation of the oxygenase (NdmC) and Rieske domains (NdmD). Genome analyses found this gene organization of a split RO and GST gene cluster to occur more broadly, implying a larger function for RO-GST protein partners.

Original languageEnglish (US)
Pages (from-to)3933-3939
Number of pages7
JournalJournal of bacteriology
Volume195
Issue number17
DOIs
StatePublished - 2013

Fingerprint

Dive into the research topics of 'Caffeine junkie: An unprecedented glutathione S-transferase-dependent oxygenase required for caffeine degradation by pseudomonas putida CBB5'. Together they form a unique fingerprint.

Cite this