Violeta Zorraquino
Universidad Pública de Navarra
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Publication
Featured researches published by Violeta Zorraquino.
Proceedings of the National Academy of Sciences of the United States of America | 2009
Cristina Solano; Begoña García; Cristina Latasa; Alejandro Toledo-Arana; Violeta Zorraquino; Jaione Valle; Joan Casals; Enrique Pedroso; Iñigo Lasa
Bacteria have developed an exclusive signal transduction system involving multiple diguanylate cyclase and phosphodiesterase domain-containing proteins (GGDEF and EAL/HD-GYP, respectively) that modulate the levels of the same diffusible molecule, 3′-5′-cyclic diguanylic acid (c-di-GMP), to transmit signals and obtain specific cellular responses. Current knowledge about c-di-GMP signaling has been inferred mainly from the analysis of recombinant bacteria that either lack or overproduce individual members of the pathway, without addressing potential compensatory effects or interferences between them. Here, we dissected c-di-GMP signaling by constructing a Salmonella strain lacking all GGDEF-domain proteins and then producing derivatives, each restoring 1 protein. Our analysis showed that most GGDEF proteins are constitutively expressed and that their expression levels are not interdependent. Complete deletion of genes encoding GGDEF-domain proteins abrogated virulence, motility, long-term survival, and cellulose and fimbriae synthesis. Separate restoration revealed that 4 proteins from Salmonella and 1 from Yersinia pestis exclusively restored cellulose synthesis in a c-di-GMP–dependent manner, indicating that c-di-GMP produced by different GGDEF proteins can activate the same target. However, the restored strain containing the STM4551-encoding gene recovered all other phenotypes by means of gene expression modulation independently of c-di-GMP. Specifically, fimbriae synthesis and virulence were recovered through regulation of csgD and the plasmid-encoded spvAB mRNA levels, respectively. This study provides evidence that the regulation of the GGDEF-domain proteins network occurs at 2 levels: a level that strictly requires c-di-GMP to control enzymatic activities directly, restricted to cellulose synthesis in our experimental conditions, and another that involves gene regulation for which c-di-GMP synthesis can be dispensable.
Journal of Bacteriology | 2013
Violeta Zorraquino; Begoña García; Cristina Latasa; Maite Echeverz; Alejandro Toledo-Arana; Jaione Valle; Iñigo Lasa; Cristina Solano
Cyclic 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 ΔycgR 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.
Archive | 2008
Cristina Solano; Begoña García; Alejandro Toledo-Arana; Cristina Latasa; Violeta Zorraquino; Jaione Valle; Iñigo Lasa
Archive | 2011
Violeta Zorraquino; Begoña García; Cristina Latasa Osta; Jaione Valle Turrillas; Alejandro Toledo-Arana; Iñigo Lasa; Cristina Solano Goñi
Archive | 2010
Cristina Solano Goñi; Jaione Valle Turrillas; Alejandro Toledo-Arana; Begoña García; Cristina Latasa Osta; Maite Villanueva; Violeta Zorraquino; Igor Ruiz de los Mozos; Iñigo Lasa
Archive | 2010
Alejandro Toledo-Arana; Maite Villanueva; Igor Ruiz de los Mozos; Jaione Valle Turrillas; Cristina Solano Goñi; Cristina Latasa Osta; Begoña García; Marta Vergara-Irigaray; Violeta Zorraquino; Iñigo Lasa
Archive | 2010
Cristina Solano Goñi; Begoña García; Cristina Latasa Osta; Alejandro Toledo-Arana; Violeta Zorraquino; Jaione Valle Turrillas; Iñigo Lasa
Archive | 2010
Cristina Latasa Osta; Cristina Solano Goñi; Begoña García; Violeta Zorraquino; Alejandro Toledo-Arana; Jaione Valle Turrillas; Iñigo Lasa
Archive | 2010
Jaione Valle Turrillas; Begoña García; Cristina Solano Goñi; Alejandro Toledo-Arana; Cristina Latasa Osta; Marta Vergara-Irigaray; Maite Villanueva; Violeta Zorraquino; Igor Ruiz de los Mozos; Iñigo Lasa
Archive | 2010
Violeta Zorraquino; Begoña García; Cristina Latasa Osta; Jaione Valle Turrillas; Alejandro Toledo-Arana; Iñigo Lasa; Cristina Solano Goñi