title: Streptococcus pneumoniae TIGR4 Flavodoxin: Structural and Biophysical Characterization of a Novel Drug Target.
abstract: Streptococcus pneumoniae (Sp) strain TIGR4 is a virulent, encapsulated serotype that causes bacteremia, otitis media, meningitis and pneumonia. Increased bacterial resistance and limited efficacy of the available vaccine to some serotypes complicate the treatment of diseases associated to this microorganism. Flavodoxins are bacterial proteins involved in several important metabolic pathways. The Sp flavodoxin (Spfld) gene was recently reported to be essential for the establishment of meningitis in a rat model, which makes SpFld a potential drug target. To facilitate future pharmacological studies, we have cloned and expressed SpFld in E. coli and we have performed an extensive structural and biochemical characterization of both the apo form and its active complex with the FMN cofactor. SpFld is a short-chain flavodoxin containing 146 residues. Unlike the well-characterized long-chain apoflavodoxins, the Sp apoprotein displays a simple two-state thermal unfolding equilibrium and binds FMN with moderate affinity. The X-ray structures of the apo and holo forms of SpFld differ at the FMN binding site, where substantial rearrangement of residues at the 91-100 loop occurs to permit cofactor binding. This work will set up the basis for future studies aiming at discovering new potential drugs to treat S. pneumoniae diseases through the inhibition of SpFld.
authors.affiliation: Department of Biochemistry and Molecular and Cell Biology, University of Zaragoza, Zaragoza, Spain.|Institute of Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, Joint Unit IQFR-CSIC-BIFI, Joint Unit EEAD-CSIC-BIFI, Mariano Esquillor s/n, Campus Rio Ebro, Edificio I+D, Zaragoza, Spain.
authors.forename: Ángela
authors.initials: Á
authors.lastname: Rodríguez-Cárdenas
authors.affiliation: Structural Biology Unit, CIC bioGUNE, Bizkaia Technology Park, Derio, Spain.
authors.forename: Adriana L
authors.initials: AL
authors.lastname: Rojas
authors.affiliation: Department of Biochemistry and Molecular and Cell Biology, University of Zaragoza, Zaragoza, Spain.|Institute of Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, Joint Unit IQFR-CSIC-BIFI, Joint Unit EEAD-CSIC-BIFI, Mariano Esquillor s/n, Campus Rio Ebro, Edificio I+D, Zaragoza, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Conde-Giménez
authors.affiliation: Institute of Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, Joint Unit IQFR-CSIC-BIFI, Joint Unit EEAD-CSIC-BIFI, Mariano Esquillor s/n, Campus Rio Ebro, Edificio I+D, Zaragoza, Spain.|Aragon Health Research Institute (IIS Aragón), University of Zaragoza, Zaragoza, Spain.|Fundación ARAID, Government of Aragón, Zaragoza, Spain.
authors.forename: Adrián
authors.initials: A
authors.lastname: Velázquez-Campoy
authors.affiliation: Institute of Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, Joint Unit IQFR-CSIC-BIFI, Joint Unit EEAD-CSIC-BIFI, Mariano Esquillor s/n, Campus Rio Ebro, Edificio I+D, Zaragoza, Spain.|Aragon Health Research Institute (IIS Aragón), University of Zaragoza, Zaragoza, Spain.|Fundación ARAID, Government of Aragón, Zaragoza, Spain.
authors.forename: Ramón
authors.initials: R
authors.lastname: Hurtado-Guerrero
authors.affiliation: Department of Biochemistry and Molecular and Cell Biology, University of Zaragoza, Zaragoza, Spain.|Institute of Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, Joint Unit IQFR-CSIC-BIFI, Joint Unit EEAD-CSIC-BIFI, Mariano Esquillor s/n, Campus Rio Ebro, Edificio I+D, Zaragoza, Spain.|Aragon Health Research Institute (IIS Aragón), University of Zaragoza, Zaragoza, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Sancho
mesh_terms: D001059:Apoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray; D005486:Flavin Mononucleotide / Q000378:metabolism*; D005418:Flavodoxin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D011008:Pneumococcal Infections / Q000382:microbiology; D011485:Protein Binding; D011487:Protein Conformation; D055550:Protein Stability; D058767:Protein Unfolding; D013296:Streptococcus pneumoniae / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013696:Temperature
chemical_list: D001059:Apoproteins; D005418:Flavodoxin; C026932:apoflavodoxin; D005486:Flavin Mononucleotide