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Item type:Publication, Access status: with files , Comparing the cariogenic species Streptococcus sobrinus and S. mutans on whole genome level(Co-Action Publishing, 2014-12-03); ; ; ; Background: Two closely related species of mutans streptococci, namely Streptococcus mutans and Streptococcus sobrinus, are associated with dental caries in humans. Their acidogenic and aciduric capacity is directly associated with the cariogenic potential of these bacteria. To survive acidic and temporarily harsh conditions in the human oral cavity with hundreds of other microbial co-colonizers as competitors, both species have developed numerous mechanisms for adaptation. Objectives: The recently published novel genome information for both species is used to elucidate genetic similarities but especially differences and to discuss the impact on cariogenicity of the corresponding phenotypic properties including adhesion, carbohydrate uptake and fermentation, acid tolerance, signaling by two component systems, competence, and oxidative stress resistance. Conclusions: S. sobrinus can down-regulate the SpaA-mediated adherence to the pellicle. It has a smaller number of two-component signaling systems and bacteriocin-related genes than S. mutans, but all or even more immunity proteins. It lacks the central competence genes comC, comS, and comR. There are more genes coding for glucosyltransferases and a novel energy production pathway formed by lactate oxidase, which is not found in S. mutans. Both species show considerable differences in the regulation of fructan catabolism. However, both S. mutans and S. sobrinus share most of these traits and should therefore be considered as equally virulent with regard to dental caries.Publicationtype: Journal ArticleScopus© Citations 67 159 205 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Genetic variability of mutans streptococci revealed by wide whole-genome sequencing(BioMed Central, 2013-06-28); ; ; ; Background: Mutans streptococci are a group of bacteria significantly contributing to tooth decay. Their genetic variability is however still not well understood.Results: Genomes of 6 clinical S. mutans isolates of different origins, one isolate of S. sobrinus (DSM 20742) and one isolate of S. ratti (DSM 20564) were sequenced and comparatively analyzed. Genome alignment revealed a mosaic-like structure of genome arrangement. Genes related to pathogenicity are found to have high variations among the strains, whereas genes for oxidative stress resistance are well conserved, indicating the importance of this trait in the dental biofilm community. Analysis of genome-scale metabolic networks revealed significant differences in 42 pathways. A striking dissimilarity is the unique presence of two lactate oxidases in S. sobrinus DSM 20742, probably indicating an unusual capability of this strain in producing H2O2 and expanding its ecological niche. In addition, lactate oxidases may form with other enzymes a novel energetic pathway in S. sobrinus DSM 20742 that can remedy its deficiency in citrate utilization pathway.Using 67 S. mutans genomes currently available including the strains sequenced in this study, we estimates the theoretical core genome size of S. mutans, and performed modeling of S. mutans pan-genome by applying different fitting models. An "open" pan-genome was inferred.Conclusions: The comparative genome analyses revealed diversities in the mutans streptococci group, especially with respect to the virulence related genes and metabolic pathways. The results are helpful for better understanding the evolution and adaptive mechanisms of these oral pathogen microorganisms and for combating them. © 2013 Song et al.; licensee BioMed Central Ltd.Publicationtype: Journal ArticleScopus© Citations 25 423 278 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , The global impact of the delta subunit RpoE of the RNA polymerase on the proteome of Streptococcus mutans(Society for General Microbiology, 2012-01-01); ; ; ; Transcriptional specificity in low-G+C Gram-positive bacteria is maintained by RpoE, the delta subunit of the RNA polymerase. Here, we studied the effect of RpoE at the proteome level in the human dental pathogen Streptococcus mutans by comparing the ΔrpoE mutant with the wild-type under five conditions: (0) exponential growth, (1) early stationary phase, (2) acid stress, (3) oxidative stress, and (4) combined acid and oxidative stress. A total of 280 cellular protein spots were reproducibly detected, of which 97 differentially expressed protein spots were identified by MALDI-TOF MS. Lack of RpoE caused downregulation of proteins for carbohydrate metabolism and energy production, including phosphoglucomutase (PGM), the phosphopentomutase DeoB and the pyruvate formate-lyase Pfl. The ΔrpoE mutant had extensive changes in the abundance of proteins involved in acid and oxidative tolerance and protein turnover, and of chaperones, at exponential phase in the absence of stress, suggesting a potential internal stress. In addition, the mutant had reduced amounts of proteins for adaptation responses, e.g. the multiple sugar transport and metabolism enzymes required for entering early stationary phase, and the proteins for stress-defence mechanisms and glycolysis under oxidative stress. Comparison of the proteome data with the corresponding transcriptome data suggested that the effects were the result of altered transcriptional and post-transcriptional regulation. The data are consistent with the reduced transcriptional specificity of the RNA polymerase in the ΔrpoE mutant, and suggest a general impact, but not a specific regulatory role, of RpoE in stress adaptation. © 2012 SGM.Publicationtype: Journal Article90