- 1982- 1988 Studium der Biologie (Diplom)
- 1990 Promotion zum Dr. rer. nat., Universität Hohenheim
- 1996 Habilitation in Mikrobiologie, Universität Hohenheim
- 1996-2002 Vertretung der Professur für Mikrobiologie an der Carl von Ossietzky Universität Oldenburg
- seit 2002 Professorin für Mikrobiologie am Institut für Molekulare Mikrobiologie und Biotechnologie der WWU Münster

Ring-cleaving dioxygenases: cofactor-independent versus metal-containing enzymes
(Support: DFG)
2,4-Dioxygenases that catalyze the cleavage of 3-hydroxy-4(1H)quinolones to carbon monoxide and N-alkylanthranilate are cofactor-independent oxygenases with an α/β-hydrolase fold. Steady-state and transient kinetics studies are being performed to obtain insight into the kinetic parameters and the time-dependent microscopic pathway of the reaction. The overall goal of the project is to contribute to a comprehensive understanding of how cofactor-free oxygenases work.
Flavonol dioxygenases also catalyze the cleavage of two carbon-carbon bonds with release of carbon monoxide, but depend on a divalent metal ion for catalysis. This raises the question of whether CO-forming dioxygenases have evolved fundamentally different ways to catalyze a similar reaction, or whether there are close mechanistic similarities of metal-dependent and cofactor-independent enzymes. Comparison of kinetic, spectroscopic and structural properties of different metal forms of flavonol dioxygenase with the properties of cofactor-independent dioxygenases will contribute to enlighten similarities and differences of the respective reaction mechanisms.

Bacterial metabolism of 2-methylquinoline and naturally occurring 2-alkyl-4(1H)quinolones
(Support: DFG)
2-Methylquinoline degradation by Arthrobacter nitroguajacolicus Rü61a to anthranilate is encoded by operons located on the linear plasmid pAL1. Anthranilate can be degraded via a chromosomal catechol pathway, however, another operon of pAL1 was proposed to encode enzymes for anthranilate conversion via coenzyme A intermediates. The project aims at characterizing the transcriptional regulation of catabolic operons of pAL1.
We also address the question of how bacteria degrade naturally occurring alkylquinolones, such as 2-heptyl-4(1H)quinolone and 2-heptyl-3-hydroxy-4(1H)quinolone, which are important quorum sensing signalling molecules of Pseudomonas aeruginosa. The goal is to identify novel enzymes for the inactivation of these compounds.

http://mibi1.uni-muenster.de/Biologie.IMMB.Fetzner/en/Publikationen/index.html

Fischer F, Künne S, Fetzner S (1999) Bacterial 2,4-dioxygenases: New members of the alpha/beta hydrolase-fold superfamily of enzymes functionally related to serine hydrolases. J. Bacteriol. 181: 5725 - 5733.

Fetzner S (2002) Oxygenases without requirement for cofactors or metal ions. Appl. Microbiol. Biotechnol. 60: 243-257.

Parschat K, Hauer B, Kappl R, Kraft R, Hüttermann J, Fetzner S (2003) Gene cluster of Arthrobacter ilicis Rü61a involved in the degradation of quinaldine to anthranilate. Characterization and functional expression of the quinaldine 4-oxidase qoxLMS genes. J. Biol. Chem. 278: 27483-27494.

Frerichs-Deeken U, Ranguelova K, Kappl R, Hüttermann J, Fetzner S (2004) Dioxygenases without requirement for cofactors, and their chemical model reaction: Compulsory order ternary complex mechanism of 1H-3-hydroxy-4-oxoquinaldine 2,4-dioxygenase involving general base catalysis by histidine 251 and single-electron oxidation of the substrate dianion. Biochemistry 43: 14485-14499.

Overhage J, Sielker S, Homburg S, Parschat K, Fetzner S (2005) Identification of large linear plasmids in Arthrobacter spp. encoding the degradation of quinaldine to anthranilate. Microbiology 151: 491-500.

Kappl R, Sielker S, Ranguelova K, Wegner J, Parschat K, Hüttermann J, Fetzner S (2006) Spectroscopic and biochemical studies on protein variants of quinaldine 4-oxidase: role of E736 in catalysis and effects of serine ligands on the FeSI and FeSII clusters. Biochemistry 45: 14853-14868.

Kolkenbrock S, Parschat K, Beermann B, Hinz H-J, Fetzner S (2006) N-Acetylanthranilate amidase from Arthrobacter nitroguajacolicus Rü61a, an alpha/beta-hydrolase-fold protein active towards aryl-acylamides and -esters, and properties of its cysteine-deficient variant. J. Bacteriol. 188: 8430-8440.

Parschat K, Overhage J, Henne A, Strittmatter AW, Gottschalk G, Fetzner S (2007) Complete nucleotide sequence of the 113 kb linear catabolic plasmid pAL1 of Arthrobacter nitroguajacolicus Rü61a, and transcriptional analysis of genes involved in quinaldine degradation. J. Bacteriol. 189: 3855-3867.

Fetzner S (2007) Cofactor-independent oxygenases go it alone. Nature Chem. Biol. 3: 374-375.

Merkens H, Kappl R, Jakob RP, Schmid FX, Fetzner S (2008) Quercetinase QueD of Streptomyces sp. FLA, a monocupin dioxygenase with a preference for nickel and cobalt. Biochemistry 47: 12185-12196.