title: A new member of the aldo-keto reductase family from the plant pathogen Xylella fastidiosa.
abstract: The Xylella fastidiosa genome program generated a large number of gene sequences that belong to pathogenicity, virulence and adaptation categories from this important plant pathogen. One of these genes (XF1729) encodes a protein similar to a superfamily of aldo-keto reductase together with a number of structurally and functionally related NADPH-dependent oxidoreductases. In this work, the similar sequence XF1729 from X. fastidiosa was cloned onto the pET32Xa/LIC vector in order to overexpress a recombinant His-tag fusion protein in Escherichia coli BL21(DE3). The expressed protein in the soluble fraction was purified by immobilized metal affinity chromatography (agarose-IDA-Ni resin). Secondary structure contents were verified by circular dichroism spectroscopy. Small angle X-ray scattering (SAXS) measurements furnish general structural parameters and provide a strong indication that the protein has a monomeric form in solution. Also, ab initio calculations show that the protein has some similarities with a previously crystallized aldo-keto reductase protein. The recombinant XF1729 purified to homogeneity catalyzed the reduction of dl-glyceraldehyde (K(cat) 2.26s(-1), Km 8.20+/-0.98 mM) and 2-nitrobenzaldehyde (K(cat) 11.74 s(-1), Km 0.14+/-0.04 mM) in the presence of NADPH. The amino acid sequence deduced from XF1729 showed the highest identity (40% or higher) with several functional unknown proteins. Among the identified AKRs, we found approximately 29% of identity with YakC (AKR13), 30 and 28% with AKR11A and AKR11B, respectively. The results establish XF1729 as the new member of AKR family, AKR13B1. Finally, the first characterization by gel filtration chromatography assays indicates that the protein has an elongated shape, which generates an apparent higher molecular weight. The study of this protein is an effort to fight X. fastidiosa, which causes tremendous losses in many economically important plants.
authors.affiliation: Centro de Biologia Molecular e Engenharia Genética, Departamento de Genética e Evolução, Instituto de Biologia, Universidade Estadual de Campinas, C.P. 6010, 13083-875 Campinas, SP, Brazil.
authors.forename: Luciana K
authors.initials: LK
authors.lastname: Rosselli
authors.forename: Cristiano L P
authors.initials: CL
authors.lastname: Oliveira
authors.forename: Adriano R
authors.initials: AR
authors.lastname: Azzoni
authors.forename: Susely F S
authors.initials: SF
authors.lastname: Tada
authors.forename: Cleide F
authors.initials: CF
authors.lastname: Catani
authors.forename: Antonio M
authors.initials: AM
authors.lastname: Saraiva
authors.forename: José Sérgio M
authors.initials: JS
authors.lastname: Soares
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Medrano
authors.forename: Iris L
authors.initials: IL
authors.lastname: Torriani
authors.forename: Anete P
authors.initials: AP
authors.lastname: Souza
mesh_terms: D000429:Alcohol Oxidoreductases / Q000737:chemistry* / Q000302:isolation & purification* / Q000378:metabolism; D000449:Aldehyde Reductase; D000074408:Aldo-Keto Reductases; D000595:Amino Acid Sequence; D003198:Computer Simulation; D004789:Enzyme Activation; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011487:Protein Conformation; D044167:Xylella / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism
chemical_list: D000429:Alcohol Oxidoreductases; D000074408:Aldo-Keto Reductases; D000449:Aldehyde Reductase