title: Organic cofactors in the metabolism of Dehalococcoides mccartyi strains.
abstract: Dehalococcoides mccartyi strains are strictly anaerobic organisms specialized to grow with halogenated compounds as electron acceptor via a respiratory process. Their genomes are among the smallest known for free-living organisms, and the embedded gene set reflects their strong specialization. Here, we briefly review main characteristics of published Dehalococcoides genomes and show how genome information together with cultivation and biochemical experiments have contributed to our understanding of Dehalococcoides physiology and biochemistry. We extend this approach by the detailed analysis of cofactor metabolism in Dehalococcoides strain CBDB1. Dehalococcoides genomes were screened for encoded proteins annotated to contain or interact with organic cofactors, and the expression of these proteins was analysed by shotgun proteomics to shed light on cofactor requirements. In parallel, cultivation experiments testing for vitamin requirements showed that cyanocobalamin (vitamin B12), thiamine and biotin were essential supplements and that cyanocobalamin could be substituted by dicyanocobinamide and dimethylbenzimidazole. Dehalococcoides genome analysis, detection of single enzymes by shotgun proteomics and inhibition studies confirmed the expression of the biosynthetic pathways for pyridoxal-5-phosphate, flavin nucleotides, folate, S-adenosylmethionine, pantothenate and nicotinic acids in strain CBDB1. Haem/cytochromes, quinones and lipoic acids were not necessary for cultivation or dechlorination activity and no biosynthetic pathways were identified in the genomes.
authors.affiliation: Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research-UFZ, 04318 Leipzig, Germany.
authors.forename: Christian J
authors.initials: CJ
authors.lastname: Schipp
authors.forename: Ernest
authors.initials: E
authors.lastname: Marco-Urrea
authors.forename: Anja
authors.initials: A
authors.lastname: Kublik
authors.forename: Jana
authors.initials: J
authors.lastname: Seifert
authors.forename: Lorenz
authors.initials: L
authors.lastname: Adrian
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001710:Biotin / Q000096:biosynthesis / Q000378:metabolism; D041862:Chloroflexi / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D003067:Coenzymes / Q000096:biosynthesis / Q000378:metabolism*; D045728:Corrinoids / Q000378:metabolism; D005492:Folic Acid / Q000096:biosynthesis; D016680:Genome, Bacterial; D058977:Molecular Sequence Annotation; D009570:Nitriles / Q000378:metabolism; D009942:Organometallic Compounds / Q000378:metabolism; D010205:Pantothenic Acid / Q000096:biosynthesis / Q000378:metabolism; D013045:Species Specificity; D013762:Tetrahydrofolate Dehydrogenase / Q000378:metabolism; D013831:Thiamine / Q000096:biosynthesis / Q000378:metabolism; D014805:Vitamin B 12 / Q000096:biosynthesis / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D003067:Coenzymes; D045728:Corrinoids; D009570:Nitriles; D009942:Organometallic Compounds; C513735:dicyanocobinamide; D010205:Pantothenic Acid; D001710:Biotin; D005492:Folic Acid; D013762:Tetrahydrofolate Dehydrogenase; D014805:Vitamin B 12; D013831:Thiamine