title: The molybdate-binding protein (ModA) of the plant pathogen Xanthomonas axonopodis pv. citri.
abstract: The modABC operon of phytopathogen Xanthomonas axonopodis pv. citri (X. citri) encodes a putative ABC transporter involved in the uptake of the molybdate and tungstate anions. Sequence analyses showed high similarity values of ModA orthologs found in X. campestris pv. campestris (X. campestris) and Escherichia coli. The X. citri modA gene was cloned in pET28a and the recombinant protein, expressed in the E. coli BL21 (DE3) strain, purified by immobilized metal affinity chromatography. The purified protein remained soluble and specifically bound molybdate and tungstate with K(d) 0.29+/-0.12 microM and 0.58+/-0.14 microM, respectively. Additionally binding of molybdate drastically enhanced the thermal stability of the recombinant ModA as compared to the apoprotein. This is the first characterization of a ModA ortholog expressed by a phytopathogen and represents an important tool for functional, biochemical and structural analyses of molybdate transport in Xanthomonas species.
authors.affiliation: Department of Microbiology, Biomedical Sciences Institute, University of São Paulo, São Paulo, SP 05008-900, Brazil. abalan@usp.br
authors.forename: Andrea
authors.initials: A
authors.lastname: Balan
authors.forename: Carolina P
authors.initials: CP
authors.lastname: Santacruz
authors.forename: Alexandre
authors.initials: A
authors.lastname: Moutran
authors.forename: Rita C C
authors.initials: RC
authors.lastname: Ferreira
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Medrano
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Pérez
authors.forename: Carlos H I
authors.initials: CH
authors.lastname: Ramos
authors.forename: Luís C S
authors.initials: LC
authors.lastname: Ferreira
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D003001:Cloning, Molecular; D008982:Molybdenum / Q000378:metabolism*; D009876:Operon; D033902:Periplasmic Binding Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D017510:Protein Folding; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D013816:Thermodynamics; D017973:Tungsten Compounds / Q000378:metabolism; D014974:Xanthomonas / Q000235:genetics* / Q000378:metabolism
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D033902:Periplasmic Binding Proteins; D011994:Recombinant Proteins; D017973:Tungsten Compounds; C044659:molybdate; D008982:Molybdenum; C045951:tungstate