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Biomolecular study of spx controlled genes related to oxidative stress in Streptococcus mutans

Grant number: 14/03816-4
Support type:Scholarships abroad - Research Internship - Doctorate
Effective date (Start): August 01, 2014
Effective date (End): November 30, 2014
Field of knowledge:Health Sciences - Dentistry - Social and Preventive Dentistry
Principal researcher:Pedro Luiz Rosalen
Grantee:Lívia Câmara de Carvalho Galvão
Supervisor abroad: José A. Lemos
Home Institution: Faculdade de Odontologia de Piracicaba (FOP). Universidade Estadual de Campinas (UNICAMP). Piracicaba , SP, Brazil
Research place: University of Rochester (UR), United States  
Associated to the scholarship:12/02278-3 - Construction and phenotypic characterization of Streptococcus mutans mutants strains of genes related to virulence, BP.DR


Dental caries is an infectious and multifactorial disease, biofilm dependent, which has Streptococcus mutans as the main etiological agent. The virulence of S. mutans resides in its abilities to adhere and form biofilms on tooth surfaces, to produce organic acids and to tolerate environmental stresses, particularly acid and oxidative stresses. How S. mutans is able to emerge as the dominant flora in oral biofilms during adverse conditions has been the central question in numerous studies. It is known that Clp system (ATP-dependent caseinolytic protease) plays a central role in tolerance against environment stress by this microorganism and that the proteolytic control of the oxidative stress regulators SpxA and SpxB by the ClpXP proteolytic system is central for stress survival. Transcriptional profiling of spxA and spxB mutants (”spxA, ”spxB and ”spxAB) identified a number of genes encoding hypothetical proteins under control of SpxA/B that can potentially participate in processes associated with detoxification and protection against reactive oxygen species (ROS). In the PhD linked project (FAPESP #2012/02278-3), we proposed to study a subset of these genes by creating isogenic strains followed by the phenotypic characterization of each gene. In fact, 10 isogenic mutant strains have been constructed, smu143c, smu144c, smu248, smu569, smu570, smu929, smu1296, smu1497, smu1685 and smu1784c (FAPESP 2012/02278-3). Based on the initial characterization of the single mutants, we propose to use a phenotype enhancement screen (PHS) to further characterize the role of selected genes in oxidative stress. The PHS will consist on the isolation of double mutants on selected genes from linked PhD project (FAPESP #2012/02278-3) paired with spxA or dpr that will be followed by a thorough phenotypic characterization. In addition, we propose to use in vitro transcription assays to investigate whether the chosen genes are directly or indirectly regulated by Spx. (AU)

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Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
GANGULY, TRIDIB; KAJFASZ, JESSICA K.; MILLER, JAMES H.; RABINOWITZ, ERIC; GALVAO, LIVIA C. C.; ROSALEN, PEDRO L.; ABRANCHES, JACQUELINE; LEMOS, JOSE A. Disruption of a Novel Iron Transport System Reverses Oxidative Stress Phenotypes of a dpr Mutant Strain of Streptococcus mutans. Journal of Bacteriology, v. 200, n. 14 JUL 2018. Web of Science Citations: 1.
GALVAO, L. C. C.; ROSALEN, P. L.; RIVERA-RAMOS, I.; FRANCO, G. C. N.; KAJFASZ, J. K.; ABRANCHES, J.; BUENO-SILVA, B.; KOO, H.; LEMOS, J. A. Inactivation of the spxA1 or spxA2 gene of Streptococcus mutans decreases virulence in the rat caries model. Molecular Oral Microbiology, v. 32, n. 2, p. 142-153, APR 2017. Web of Science Citations: 7.
GALVAO, LVIA C. C.; MILLER, JAMES H.; KAJFASZ, JESSICA K.; SCOTT-ANNE, KATHY; FREIRES, IRLAN A.; FRANCO, GILSON C. N.; ABRANCHES, JACQUELINE; ROSALEN, PEDRO L.; LEMOS, JOSE A. Transcriptional and Phenotypic Characterization of Novel Spx-Regulated Genes in Streptococcus mutans. PLoS One, v. 10, n. 4 APR 23 2015. Web of Science Citations: 12.

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