title: High affinity binding of albicidin phytotoxins by the AlbA protein from Klebsiella oxytoca.
abstract: Albicidins are a family of phytotoxins and antibiotics which play an important role in the pathogenesis of sugarcane leaf scald disease. The albA gene from Klebsiella oxytoca encodes a protein which inactivates albicidin by heat-reversible binding. Albicidin ligand binding to a recombinant AlbA protein, purified by means of a glutathione S-transferase gene fusion system, is an almost instant and saturable reaction. Kinetic and stoichiometric analysis of the binding reaction indicated the presence of a single high affinity binding site with a dissociation constant of 6.4 x 10(-8) M. The AlbA-albicidin complex is stable from 4 to 40 degrees C, from pH 5 to 9 and in high salt solutions. Treatment with protein denaturants released all bound albicidin. These properties indicate that AlbA may be a useful affinity matrix for selective purification of albicidin antibiotics. AlbA does not bind to p-nitrophenyl butyrate or alpha-naphthyl butyrate, the substrates of the albicidin detoxification enzyme AlbD from Pantoea dispersa. The potential exists to pyramid genes for different mechanisms in transgenic plants to protect plastid DNA replication from inhibition by albicidins.
authors.affiliation: Department of Botany, The University of Queensland, Brisbane QLD 4072, Australia.
authors.forename: Lianhui
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Botany, The University of Queensland, Brisbane QLD 4072, Australia.
authors.forename: Jinling
authors.initials: J
authors.lastname: Xu
authors.affiliation: Department of Botany, The University of Queensland, Brisbane QLD 4072, Australia.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Birch
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism; D002087:Butyrates / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D003001:Cloning, Molecular; D004926:Escherichia coli; D015870:Gene Expression; D005982:Glutathione Transferase / Q000235:genetics; D007700:Kinetics; D007709:Klebsiella / Q000235:genetics / Q000378:metabolism*; D009284:Naphthols / Q000378:metabolism; D009930:Organic Chemicals; D010957:Plasmids; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000378:metabolism*; D014974:Xanthomonas
chemical_list: C111474:AlbA protein, Klebsiella oxytoca; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002087:Butyrates; D002352:Carrier Proteins; D009284:Naphthols; D009930:Organic Chemicals; D011993:Recombinant Fusion Proteins; C033592:4-nitrophenyl butyrate; C046156:albicidin; C029204:alpha-naphthyl butyrate; D005982:Glutathione Transferase