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Structure-function studies of iron-sulfur enzyme systems

Friemann, Rosmarie (2005). Structure-function studies of iron-sulfur enzyme systems. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae. Agraria, 1401-6249 ; 504
ISBN 91-576-6783-7
[Doctoral thesis]

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Iron-sulfur clusters are among the most ancient of metallocofactors and serve a variety of biological functions in proteins, including electron transport, catalytic, and structural roles. Two kinds of multicomponent enzyme systems have been investigated by X-ray crystallography, the ferredoxin/thioredoxin system and bacterial Rieske non-heme iron dioxygenase (RDO) systems. The ferredoxin/thioredoxin system is a light sensitive system controlling the activities of key enzymes involved in the assimilatory (photosynthetic) and dissimilatory pathways in chloroplasts and photosynthetic bacteria. The system consists of a ferredoxin, ferredoxin:thioredoxin reductase (FTR), and two thioredoxins, Trx-m and Trx-f. In light, photosystem I reduces ferredoxin that reduces Trx-m and Trx-f. This two-electron reduction is catalyzed by FTR that contains a [4Fe-4S] center and a proximal disulfide bridge. When the first electron is delivered by the ferredoxin, an intermediate is formed where one thiol of the proximal disulfide attacks the disulfide bridge of thioredoxin. This results in a transient protein-protein complex held together by a mixed disulfide between FTR and Trx-m. This complex is stabilized by using a C40S mutant Trx-m and its structure have been determined. RDOs consists of a flavoprotein reductase and often a ferredoxin that transfer electrons from NAD(P)H to the terminal dioxygenase. The terminal dioxygenase catalyze the enantioselective addition of dioxygen in the initial degradation of aromatic compounds, producing cis-dihydrodiols. The structures of three dioxygenases, nitrobenzene dioxygenase (NBDO), 2-nitrotoluene (2NTDO) and toluene dioxygenase (TDO), as well as the two electron transfer proteins of the TDO system, toluene dioxygenase reductase (TDOR) and toluene dioxygenase ferredoxin (TDOF), have been determined. The dioxygenase structures are all alpha3beta3 heterohexamers similar to other RDOs. The catalytic a subunit contains a Rieske iron-sulfur cluster and a mononuclear iron at the active site. 2NTDO and NBDO are both able to degrade nitroaromatic compounds. Their structures and structures of NBDO in complex with two nitroarene substrates reveal the structural basis for the dihydroxylation of nitroarene compounds. The electron transfer pathway from NADH via TDOR and the TDOF to the TDO is described in relation to the obtained structures of the TDO system.

Authors/Creators:Friemann, Rosmarie
Title:Structure-function studies of iron-sulfur enzyme systems
Series Name/Journal:Acta Universitatis Agriculturae Sueciae. Agraria
Year of publishing :2005
Number of Pages:47
ALLI. Friemann, R., Schmidt, H., Ramaswamy, S., Forstner, M., Krauth-Siegel, R.L., Eklund, H. (2003). Structure of thioredoxin from Trypanosoma brucei brucei. FEBS lett. 554, 301-5. II. Friemann, R., Eklund, H., Manieri W., Schürmann P., & Dai S. (2004). Structure of the ferredoxin: thioredoxin reductase-thioredoxin-m complex. In manuscript. III. Lee, K., Friemann, R., Parales, J.V., Gibson D.T., & Ramaswamy S. (2004). Purification, crystallization and premilinary X-ray diffraction studies of the three components of the Toluene 2,3-dioxygenase enzyme system, (2004). In manuscript. IV. Friemann, R., Lee, K., Gibson, D.T., Eklund, H., & Ramaswamy, S. (2004). Structural basis of electron transfer in the multicomponent Rieske non-heme Toluene 2,3-dioxygenase enzyme system. In manuscript. V. Parales, R.E., Huang R., Yu, C.-L., Parales, J.V., Lee, F.K.N., Lessner, D.J., Ivkovic-Jensen, M.M, Liu, W., Friemann, R., Ramaswamy, S., & Gibson, D.T. (2004). Purification, characterization, and crystallization of the components of the Nitrobenzene and 2-Nitrotoluene enzyme systems. (2004). Submitted, App. Environ. Microbiol. VI. Friemann, R., Ivkovic-Jensen, M.M., Lessner, D.J., Yu, C.-L., Gibson, D.T., Parales, R.E., Eklund, H., & Ramaswamy, S. (2004). Structural insight into the dioxygenation of nitroarene compounds: The crystal structure of Nitrobenzene dioxygenase. (2004). Submitted, J. Mol. Biol.
Place of Publication:Uppsala
ISBN for printed version:91-576-6783-7
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:iron, sulphur, enzymes, enzyme activity, analytical methods, molecular biology
Keywords:Iron-sulfur protein, Rieske non-heme iron dioxygenase, ferredoxin thioredoxin:reductase, thioredoxin, nitroarene, X-ray crystallography
Permanent URL:
ID Code:739
Department:(NL, NJ) > Dept. of Molecular Biology (until 131231)
Deposited By: Rosmarie Friemann
Deposited On:07 Apr 2009 00:00
Metadata Last Modified:02 Dec 2014 10:06

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