@article{WarelowOkeSchoeppCothenetetal.2013,
  author    = {Warelow, Thomas P. and Oke, Muse and Schoepp-Cothenet, Barbara and Dahl, Jan U. and Bruselat, Nicole and Sivalingam, Ganesh N. and Leimk{\"u}hler, Silke and Thalassinos, Konstantinos and Kappler, Ulrike and Naismith, James H. and Santini, Joanne M.},
  title     = {The Respiratory Arsenite Oxidase: Structure and the Role of Residues Surrounding the Rieske Cluster},
  series = {PLOS ONE},
  volume    = {8},
  journal   = {PLOS ONE},
  number    = {8},
  publisher = {PUBLIC LIBRARY SCIENCE},
  address   = {SAN FRANCISCO},
  issn      = {1932-6203},
  doi       = {10.1371/journal.pone.0072535},
  pages     = {10},
  year      = {2013},
  abstract  = {The arsenite oxidase (Aio) from the facultative autotrophic Alphaproteobacterium Rhizobium sp. NT-26 is a bioenergetic enzyme involved in the oxidation of arsenite to arsenate. The enzyme from the distantly related heterotroph, Alcaligenes faecalis, which is thought to oxidise arsenite for detoxification, consists of a large alpha subunit (AioA) with bis-molybdopterin guanine dinucleotide at its active site and a 3Fe-4S cluster, and a small beta subunit (AioB) which contains a Rieske 2Fe-2S cluster. The successful heterologous expression of the NT-26 Aio in Escherichia coli has resulted in the solution of its crystal structure. The NT-26 Aio, a heterotetramer, shares high overall similarity to the heterodimeric arsenite oxidase from A. faecalis but there are striking differences in the structure surrounding the Rieske 2Fe-2S cluster which we demonstrate explains the difference in the observed redox potentials (+225 mV vs. +130/160 mV, respectively). A combination of site-directed mutagenesis and electron paramagnetic resonance was used to explore the differences observed in the structure and redox properties of the Rieske cluster. In the NT-26 AioB the substitution of a serine (S126 in NT-26) for a threonine as in the A. faecalis AioB explains a -20 mV decrease in redox potential. The disulphide bridge in the A. faecalis AioB which is conserved in other betaproteobacterial AioB subunits and the Rieske subunit of the cytochrome bc(1) complex is absent in the NT-26 AioB subunit. The introduction of a disulphide bridge had no effect on Aio activity or protein stability but resulted in a decrease in the redox potential of the cluster. These results are in conflict with previous data on the betaproteobacterial AioB subunit and the Rieske of the bc(1) complex where removal of the disulphide bridge had no effect on the redox potential of the former but a decrease in cluster stability was observed in the latter.},
  language  = {en}
}
@article{HaenzelmannDahlKuperetal.2009,
  author    = {Haenzelmann, Petra and Dahl, Jan U. and Kuper, Jochen and Urban, Alexander and Mueller-Theissen, Ursula and Leimk{\"u}hler, Silke and Schindelin, Hermann},
  title     = {Crystal structure of YnjE from Escherichia coli, a sulfurtransferase with three rhodanese domains},
  issn      = {0961-8368},
  doi       = {10.1002/pro.260},
  year      = {2009},
  abstract  = {Rhodaneses/sulfurtransferases are ubiquitous enzymes that catalyze the transfer of sulfane sulfur from a donor molecule to a thiophilic acceptor via an active site cysteine that is modified to a persulfide during the reaction. Here, we present the first crystal structure of a triple-domain rhodanese-like protein, namely YnjE from Escherichia coli, in two states where its active site cysteine is either unmodified or present as a persulfide. Compared to well- characterized tandem domain rhodaneses, which are composed of one inactive and one active domain, YnjE contains an extra N-terminal inactive rhodanese-like domain. Phylogenetic analysis reveals that YnjE triple-domain homologs can be found in a variety of other gamma-proteobacteria, in addition, some single-, tandem-, four and even six-domain variants exist. All YnjE rhodaneses are characterized by a highly conserved active site loop (CGTGWR) and evolved independently from other rhodaneses, thus forming their own subfamily. On the basis of structural comparisons with other rhodaneses and kinetic studies, YnjE, which is more similar to thiosulfate:cyanide sulfurtransferases than to 3- mercaptopyruvate:cyanide sulfurtransferases, has a different substrate specificity that depends not only on the composition of the active site loop with the catalytic cysteine at the first position but also on the surrounding residues. In vitro YnjE can be efficiently persulfurated by the cysteine desulfurase IscS. The catalytic site is located within an elongated cleft, formed by the central and C-terminal domain and is lined by bulky hydrophobic residues with the catalytic active cysteine largely shielded from the solvent.},
  language  = {en}
}