title: Genetic evidence that the degradation of para-cresol by Geobacter metallireducens is catalyzed by the periplasmic para-cresol methylhydroxylase.
abstract: Two pathways for para-cresol (p-cresol) degradation by anaerobic bacteria have been elucidated; one involves fumarate addition at the methyl group of p-cresol by a hydroxylbenzylsuccinate synthase protein while the other utilizes a methylhydroxylase protein (PCMH) to catalyze hydroxylation of the methyl group of p-cresol. In Geobacter metallireducens, in vitro enzymatic assays showed that p-cresol is degraded via the methylhydroxylation pathway. However, prior to this study these results had not been confirmed by genetic analyses. In this work, the gene coding for benzylsuccinate-CoA dehydrogenase (bbsG), an enzyme required for toluene degradation by G. metallireducens that is homologous to the p-hydroxybenzylsuccinyl-CoA dehydrogenase involved in p-cresol degradation by Desulfobacula toluolica Tol2 via fumarate addition, and the gene encoding the alpha prime subunit of PCMH (pcmI), were deleted to investigate the possibility of co-existing p-cresol degradation pathways in G. metallireducens. The absence of a functional PcmI protein completely inhibited p-cresol degradation, while deletion of the bbsG gene had little impact. These results further support the observation that G. metallireducens utilizes a PCMH-initiated pathway for p-cresol degradation.
authors: Samsung Biomedical Research Institute, School of Medicine, Sungkyunkwan University, Suwon, South Korea 440746 Department of Microbiology, University of Massachusetts, Amherst-01003, MA, USA chaurasia@skku.edu chaurasia.ak@gmail.com.
authors: Akhilesh Kumar
authors: AK
authors: Chaurasia
authors: Department of Microbiology, University of Massachusetts, Amherst-01003, MA, USA The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2970 Hørsholm, Denmark.
authors: Pier-Luc
authors: PL
authors: Tremblay
authors: Department of Microbiology, University of Massachusetts, Amherst-01003, MA, USA.
authors: Dawn E
authors: DE
authors: Holmes
authors: Department of Microbiology, University of Massachusetts, Amherst-01003, MA, USA The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2970 Hørsholm, Denmark.
authors: Tian
authors: T
authors: Zhang
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D055162:Biocatalysis; D001673:Biodegradation, Environmental; D003408:Cresols / Q000378:metabolism*; D045302:Geobacter / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D053858:Metabolic Networks and Pathways; D006899:Mixed Function Oxygenases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019897:Periplasm / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D003408:Cresols; D006899:Mixed Function Oxygenases; C049502:4-cresol dehydrogenase (hydroxylating); C077977:cresol
keywords: Geobacter metallireducens; PCMH; para-cresol