title: The cysteine desulfurase IscS of Mycobacterium tuberculosis is involved in iron-sulfur cluster biogenesis and oxidative stress defence.
abstract: The complex multiprotein systems for the assembly of protein-bound iron-sulfur (Fe-S) clusters are well defined in Gram-negative model organisms. However, little is known about Fe-S cluster biogenesis in other bacterial species. The ISC (iron-sulfur cluster) operon of Mycobacterium tuberculosis lacks several genes known to be essential for the function of this system in other organisms. However, the cysteine desulfurase IscSMtb (Rv number Rv3025c; Mtb denotes M. tuberculosis) is conserved in this important pathogen. The present study demonstrates that deleting iscSMtb renders the cells microaerophilic and hypersensitive to oxidative stress. Moreover, the ∆iscSMtb mutant shows impaired Fe-S cluster-dependent enzyme activity, clearly indicating that IscSMtb is associated with Fe-S cluster assembly. An extensive interaction network of IscSMtb with Fe-S proteins was identified, suggesting a novel mechanism of sulfur transfer by direct interaction with apoproteins. Interestingly, the highly homologous IscS of Escherichia coli failed to complement the ∆iscSMtb mutant and showed a less diverse protein-interaction profile. To identify a structural basis for these observations we determined the crystal structure of IscSMtb, which mirrors adaptations made in response to an ISC operon devoid of IscU-like Fe-S cluster scaffold proteins. We conclude that in M. tuberculosis IscS has been redesigned during evolution to compensate for the deletion of large parts of the ISC operon.
authors.forename: Jan
authors.initials: J
authors.lastname: Rybniker
authors.affiliation: *Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
authors.forename: Florence
authors.initials: F
authors.lastname: Pojer
authors.affiliation: ‡Institut für Bio- und Geowissenschaften, IBG-1: Biotechnologie, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Marienhagen
authors.affiliation: *Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
authors.forename: Gaëlle S
authors.initials: GS
authors.lastname: Kolly
authors.affiliation: *Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Chen
authors.affiliation: †1st Department of Internal Medicine, University of Cologne, D-50937 Cologne, Germany.
authors.forename: Edeltraud
authors.initials: E
authors.lastname: van Gumpel
authors.forename: Pia
authors.initials: P
authors.lastname: Hartmann
authors.affiliation: *Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
authors.forename: Stewart T
authors.initials: ST
authors.lastname: Cole
mesh_terms: D001059:Apoproteins / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013437:Carbon-Sulfur Lyases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D003545:Cysteine / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D007506:Iron-Sulfur Proteins / Q000096:biosynthesis*; D008958:Models, Molecular; D009169:Mycobacterium tuberculosis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D009876:Operon; D018384:Oxidative Stress; D010802:Phylogeny; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000378:metabolism; D017279:Selenocysteine / Q000378:metabolism; D013379:Substrate Specificity; D020798:Two-Hybrid System Techniques
chemical_list: D001059:Apoproteins; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D007506:Iron-Sulfur Proteins; D011994:Recombinant Proteins; D017279:Selenocysteine; D013437:Carbon-Sulfur Lyases; C080546:cysteine desulfurase; D003545:Cysteine