Journal article
Delineation of the Caffeine C-8 Oxidation Pathway in Pseudomonas sp Strain CBB1 via Characterization of a New Trimethyluric Acid Monooxygenase and Genes Involved in Trimethyluric Acid Metabolism
Journal of bacteriology, Vol.194(15), pp.3872-3882
08/01/2012
DOI: 10.1128/JB.00597-12
PMCID: PMC3416557
PMID: 22609920
Abstract
The molecular basis of the ability of bacteria to live on caffeine via the C-8 oxidation pathway is unknown. The first step of this pathway, caffeine to trimethyluric acid (TMU), has been attributed to poorly characterized caffeine oxidases and a novel quinone-dependent caffeine dehydrogenase. Here, we report the detailed characterization of the second enzyme, a novel NADH-dependent trimethyluric acid monooxygenase (TmuM), a flavoprotein that catalyzes the conversion of TMU to 1,3,7-trimethyl-5-hydroxyisourate (TM-HIU). This product spontaneously decomposes to racemic 3,6,8-trimethylallantoin (TMA). TmuM prefers trimethyluric acids and, to a lesser extent, dimethyluric acids as substrates, but it exhibits no activity on uric acid. Homology models of TmuM against uric acid oxidase HpxO (which catalyzes uric acid to 5-hydroxyisourate) reveal a much bigger and hydrophobic cavity to accommodate the larger substrates. Genes involved in the caffeine C-8 oxidation pathway are located in a 25.2-kb genomic DNA fragment of CBB1, including cdhABC (coding for caffeine dehydrogenase) and tmuM (coding for TmuM). Comparison of this gene cluster to the uric acid-metabolizing gene cluster and pathway of Klebsiella pneumoniae revealed two major open reading frames coding for the conversion of TM-HIU to S-(+)-trimethylallantoin [S-(+)-TMA]. The first one, designated tmuH, codes for a putative TM-HIU hydrolase, which catalyzes the conversion of TM-HIU to 3,6,8-trimethyl-2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline (TM-OHCU). The second one, designated tmuD, codes for a putative TM-OHCU decarboxylase which catalyzes the conversion of TM-OHCU to S-(+)-TMA. Based on a combination of enzymology and gene-analysis, a new degradative pathway for caffeine has been proposed via TMU, TM-HIU, TM-OHCU to S-(+)-TMA.
Details
- Title: Subtitle
- Delineation of the Caffeine C-8 Oxidation Pathway in Pseudomonas sp Strain CBB1 via Characterization of a New Trimethyluric Acid Monooxygenase and Genes Involved in Trimethyluric Acid Metabolism
- Creators
- Sujit Kumar Mohanty - University of IowaChi-Li Yu - Univ Iowa, Dept Chem & Biochem Engn, Iowa City, IA 52242 USAShuvendu Das - University of IowaTai Man Louie - University of IowaLokesh Gakhar - University of IowaMani Subramanian - University of Iowa
- Resource Type
- Journal article
- Publication Details
- Journal of bacteriology, Vol.194(15), pp.3872-3882
- Publisher
- Amer Soc Microbiology
- DOI
- 10.1128/JB.00597-12
- PMID
- 22609920
- PMCID
- PMC3416557
- ISSN
- 0021-9193
- eISSN
- 1098-5530
- Number of pages
- 11
- Grant note
- University of Iowa
- Language
- English
- Date published
- 08/01/2012
- Academic Unit
- Center for Biocatalysis and Bioprocessing; Chemistry; Medicine Administration
- Record Identifier
- 9984622049902771
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