Person: Echeverz SarasĂșa, Maite
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Echeverz SarasĂșa
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Maite
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Ciencias de la Salud
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0000-0002-4153-4549
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810062
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Publication Open Access Evaluation of a Salmonella strain lacking the secondary messenger c-di-GMP and RpoS as a live oral vaccine(Public Library of Science, 2016) Latasa Osta, Cristina; Echeverz SarasĂșa, Maite; GarcĂa Ona, Enrique; Burgui Erice, Saioa; Casares, Noelia; HervĂĄs Stubbs, Sandra; Lasarte, Juan JosĂ©; Lasa Uzcudun, Ăñigo; Solano Goñi, Cristina; GarcĂa MartĂnez, Begoña; Gil Puig, Carmen; IdAB. Instituto de AgrobiotecnologĂa / Agrobioteknologiako Institutua; Gobierno de Navarra / Nafarroako Gobernua: IIM 13329.RI1Salmonellosis is one of the most important bacterial zoonotic diseases transmitted through the consumption of contaminated food, with chicken and pig related products being key reservoirs of infection. Although numerous studies on animal vaccination have been performed in order to reduce Salmonella prevalence, there is still a need for an ideal vaccine. Here, with the aim of constructing a novel live attenuated Salmonella vaccine candidate, we firstly analyzed the impact of the absence of cyclic-di-GMP (c-di-GMP) in Salmonella virulence. Cdi-GMP is an intracellular second messenger that controls a wide range of bacterial processes, including biofilm formation and synthesis of virulence factors, and also modulates the host innate immune response. Our results showed that a Salmonella multiple mutant in the twelve genes encoding diguanylate cyclase proteins that, as a consequence, cannot synthesize c-di-GMP, presents a moderate attenuation in a systemic murine infection model. An additional mutation of the rpoS gene resulted in a synergic attenuating effect that led to a highly attenuated strain, referred to as ÎXIII, immunogenic enough to protect mice against a lethal oral challenge of a S. Typhimurium virulent strain. ÎXIII immunogenicity relied on activation of both antibody and cell mediated immune responses characterized by the production of opsonizing antibodies and the induction of significant levels of IFN-Îł, TNF- α, IL-2, IL-17 and IL-10. ÎXIII was unable to form a biofilm and did not survive under desiccation conditions, indicating that it could be easily eliminated from the environment. Moreover, ÎXIII shows DIVA features that allow differentiation of infected and vaccinated animals. Altogether, these results show ÎXIII as a safe and effective live DIVA vaccinePublication Open Access Salmonella biofilm development depends on the phosphorylation status of RcsB(American Society for Microbiology, 2012) Latasa Osta, Cristina; GarcĂa MartĂnez, Begoña; Echeverz SarasĂșa, Maite; Toledo Arana, Alejandro; Valle Turrillas, Jaione; Campoy SĂĄnchez, Susana; GarcĂa del Portillo, Francisco; Solano Goñi, Cristina; Lasa Uzcudun, Ăñigo; IdAB. Instituto de AgrobiotecnologĂa / Agrobioteknologiako Institutua; Gobierno de Navarra / Nafarroako Gobernua: IIM13329.RI1The Rcs phosphorelay pathway is a complex signaling pathway involved in the regulation of many cell surface structures in enteric bacteria. In response to environmental stimuli, the sensor histidine kinase (RcsC) autophosphorylates and then transfers the phosphate through intermediary steps to the response regulator (RcsB), which, once phosphorylated, regulates gene expression. Here, we show that Salmonella biofilm development depends on the phosphorylation status of RcsB. Thus, unphosphorylated RcsB, hitherto assumed to be inactive, is essential to activate the expression of the biofilm matrix compounds. The prevention of RcsB phosphorylation either by the disruption of the phosphorelay at the RcsC or RcsD level or by the production of a nonphosphorylatable RcsB allele induces biofilm development. On the contrary, the phosphorylation of RcsB by the constitutive activation of the Rcs pathway inhibits biofilm development, an effect that can be counteracted by the introduction of a nonphosphorylatable RcsB allele. The inhibition of biofilm development by phosphorylated RcsB is due to the repression of CsgD expression, through a mechanism dependent on the accumulation of the small noncoding RNA RprA. Our results indicate that unphosphorylated RcsB plays an active role for integrating environmental signals and, more broadly, that RcsB phosphorylation acts as a key switch between planktonic and sessile life-styles in Salmonella enterica serovar Typhimurium.Publication Open Access Lack of the PGA exopolysaccharide in Salmonella as an adaptive trait for survival in the host(Public Library of Science, 2017) Echeverz SarasĂșa, Maite; GarcĂa MartĂnez, Begoña; Sabalza BaztĂĄn, Amaia; Valle Turrillas, Jaione; GabaldĂłn Estevan, Juan Antonio; Solano Goñi, Cristina; Lasa Uzcudun, Ăñigo; IdAB. Instituto de AgrobiotecnologĂa / Agrobioteknologiako InstitutuaMany bacteria build biofilm matrices using a conserved exopolysaccharide named PGA or PNAG (poly-ÎČ-1,6-N-acetyl-D-glucosamine). Interestingly, while E. coli and other members of the family Enterobacteriaceae encode the pgaABCD operon responsible for PGA synthesis, Salmonella lacks it. The evolutionary force driving this difference remains to be determined. Here, we report that Salmonella lost the pgaABCD operon after the divergence of Salmonella and Citrobacter clades, and previous to the diversification of the currently sequenced Salmonella strains. Reconstitution of the PGA machinery endows Salmonella with the capacity to produce PGA in a cyclic dimeric GMP (c-di-GMP) dependent manner. Outside the host, the PGA polysaccharide does not seem to provide any significant benefit to Salmonella: resistance against chlorine treatment, ultraviolet light irradiation, heavy metal stress and phage infection remained the same as in a strain producing cellulose, the main biofilm exopolysaccharide naturally produced by Salmonella. In contrast, PGA production proved to be deleterious to Salmonella survival inside the host, since it increased susceptibility to bile salts and oxidative stress, and hindered the capacity of S. Enteritidis to survive inside macrophages and to colonize extraintestinal organs, including the gallbladder. Altogether, our observations indicate that PGA is an antivirulence factor whose loss may have been a necessary event during Salmonella speciation to permit survival inside the host.Publication Open Access Coordinated cyclic-di-GMP repression of salmonella motility through YcgR and cellulose(American Society for Microbiology, 2013) Zorraquino Salvo, Violeta; GarcĂa MartĂnez, Begoña; Latasa Osta, Cristina; Echeverz SarasĂșa, Maite; Toledo Arana, Alejandro; Valle Turrillas, Jaione; Lasa Uzcudun, Ăñigo; Solano Goñi, Cristina; IdAB. Instituto de AgrobiotecnologĂa / Agrobioteknologiako Institutua; Gobierno de Navarra / Nafarroako Gobernua: 1312/2010Cyclic di-GMP (c-di-GMP) is a secondary messenger that controls a variety of cellular processes, including the switch between a biofilm and a planktonic bacterial lifestyle. This nucleotide binds to cellular effectors in order to exert its regulatory functions. In Salmonella, two proteins, BcsA and YcgR, both of them containing a c-di-GMP binding PilZ domain, are the only known c-di-GMP receptors. BcsA, upon c-di-GMP binding, synthesizes cellulose, the main exopolysaccharide of the biofilm matrix. YcgR is dedicated to c-di-GMP-dependent inhibition of motility through its interaction with flagellar motor proteins. However, previous evidences indicate that in the absence of YcgR, there is still an additional element that mediates motility impairment under high c-di-GMP levels. Here we have uncovered that cellulose per se is the factor that further promotes inhibition of bacterial motility once high c-di-GMP contents drive the activation of a sessile lifestyle. Inactivation of different genes of the bcsABZC operon, mutation of the conserved residues in the RxxxR motif of the BcsA PilZ domain, or degradation of the cellulose produced by BcsA rescued the motility defect of ÎycgR strains in which high c-di-GMP levels were reached through the overexpression of diguanylate cyclases. High c-di-GMP levels provoked cellulose accumulation around cells that impeded flagellar rotation, probably by means of steric hindrance, without affecting flagellum gene expression, exportation, or assembly. Our results highlight the relevance of cellulose in Salmonella lifestyle switching as an architectural element that is both essential for biofilm development and required, in collaboration with YcgR, for complete motility inhibition.Publication Open Access Insights into c-di-GMP signaling and the PGA exopolysaccharide biological functions using Salmonella as a model organism(2017) Echeverz SarasĂșa, Maite; Lasa Uzcudun, Ăñigo; Solano Goñi, Cristina; ProducciĂłn Agraria; Nekazaritza EkoizpenaSalmonella es un patĂłgeno alimentario de gran relevancia clĂnica capaz de adherirse a superficies y formar comunidades bacterianas embebidas en una matriz que ellas mismas producen denominadas biofilms. Esta matriz confiere a las bacterias protecciĂłn frente a agentes externos, aumentando su tolerancia frente a condiciones ambientales adversas, agentes antimicrobianos o el sistema inmune del hospedador. Existe una vĂa de señalizaciĂłn, mediada por el dinucleĂłtido cĂclico, c-di- GMP, que controla en muchas especies bacterianas la sĂntesis de diversos componentes de la matriz del biofilm, de manera que concentraciones elevadas de este nucleĂłtido activan la producciĂłn de la matriz y por lo tanto del biofilm. La formaciĂłn de biofilms en explotaciones agropecuarias y lugares donde se procesan alimentos es una fuente potencial de contaminaciĂłn y de transmisiĂłn de este patĂłgeno. Diversas medidas de higiene y seguimiento han sido implementadas por las autoridades para el control de esta bacteria; sin embargo alrededor de 93 millones de personas en todo el mundo sufren salmonelosis cada año. Por ello, la bĂșsqueda de medidas alternativas de control, basadas en la vacunaciĂłn animal, asĂ como el estudio de los mecanismos de patogenicidad y formaciĂłn de biofilm de Salmonella han sido el objeto de este trabajo.