title: Essential role of K+uptake permease (Kup) for resistance to sucrose-induced stress in Gluconacetobacter diazotrophicus PAl 5.
abstract: Microorganisms are constantly challenged by stressful conditions, such as sugar-rich environments. Such environments can cause an imbalance of biochemical activities and compromise cell multiplication. Gluconacetobacter diazotrophicus PAl 5 is among the most sugar-tolerant bacteria, capable of growing in the presence of up to 876 mM sucrose. However, the molecular mechanisms involved in its response to high sucrose remain unknown. The present work aimed to identify sucrose-induced stress resistance genes in G. diazotrophicus PAl 5. Screening of a Tn5 transposon insertion library identified a mutant that was severely compromised in its resistance to high sucrose concentrations. Molecular characterization revealed that the mutation affected the kupA gene, which encodes a K+uptake transporter (KupA). Functional complementation of the mutant with the wild type kupA gene recovered the sucrose-induced stress resistance phenotype. High sucrose resistance assay, under different potassium concentrations, revealed that KupA acts as a high-affinity K+transporter, which is essential for resistance to sucrose-induced stress, when extracellular potassium levels are low. This study is the first to show the essential role of the KupA protein for resistance to sucrose-induced stress in bacteria by acting as a high-affinity potassium transporter in G. diazotrophicus PAl 5.
authors.affiliation: Laboratório de Biotecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, UENF, Campos dos Goytacazes, RJ, Brazil.
authors.forename: Marcos V V
authors.initials: MV
authors.lastname: de Oliveira
authors.affiliation: Laboratório de Fisiologia e Bioquímica de Microrganismos, Universidade Estadual do Norte Fluminense Darcy Ribeiro, UENF, Campos dos Goytacazes, RJ, Brazil.
authors.forename: Aline C
authors.initials: AC
authors.lastname: Intorne
authors.affiliation: Laboratório de Biotecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, UENF, Campos dos Goytacazes, RJ, Brazil.
authors.forename: Luciano de S
authors.initials: LS
authors.lastname: Vespoli
authors.affiliation: Laboratório de Biotecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, UENF, Campos dos Goytacazes, RJ, Brazil.
authors.forename: Leandro F
authors.initials: LF
authors.lastname: Andrade
authors.affiliation: Laboratório de Biologia Parasitária, Pontifícia Universidade Católica do Rio Grande do Sul, PUCRS, Rio Grande do Sul, Brazil.
authors.forename: Leandro de M
authors.initials: LM
authors.lastname: Pereira
authors.affiliation: Laboratório de Biotecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, UENF, Campos dos Goytacazes, RJ, Brazil.
authors.forename: Patrícia L
authors.initials: PL
authors.lastname: Rangel
authors.affiliation: Laboratório de Biotecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, UENF, Campos dos Goytacazes, RJ, Brazil.
authors.forename: Gonçalo A
authors.initials: GA
authors.lastname: de Souza Filho
mesh_terms: D004251:DNA Transposable Elements; D005816:Genetic Complementation Test; D041821:Gluconacetobacter / Q000187:drug effects* / Q000235:genetics / Q000502:physiology*; D026901:Membrane Transport Proteins / Q000378:metabolism*; D016254:Mutagenesis, Insertional; D009997:Osmotic Pressure; D011188:Potassium / Q000378:metabolism*; D013312:Stress, Physiological; D013395:Sucrose / Q000378:metabolism*
chemical_list: D004251:DNA Transposable Elements; D026901:Membrane Transport Proteins; D013395:Sucrose; D011188:Potassium