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Role of the yxkO gene of Bacillus subtilis in responce to environmental stress.
Petrovová, Miroslava ; Lichá, Irena (advisor) ; Nešvera, Jan (referee)
ROLE OF THE YXKO GENE OF BACILLUS SUBTILIS IN RESPONCE TO ENVIRONMENTAL STRESS Abstract Mutation of the yxkO gene, which encodes a putative ribokinase and belongs to the σB general stress response regulon, leads to reduced salt tolerance under potassium limitation in Bacillus subtilis. The biological function of the yxkO gene has not been determined yet, but it may be involved in the high affinity potassium uptake system, which has been described in Escherichia coli in contrast to Bacillus subtilis. Our goal was to describe another features of a mutant in the yxkO gene and to try to propose the role of this gene. Using the integration vector pMutin4, we prepared a Bacillus subtilis strain MP2 with a yxkO gene inactivation. The MP2 strain displays limited growth in a rich medium and it is a sensitive strain to tetracycline. Furthermore, this strain is unable to form endospores and the cells are longer, which indicates a septum formation defect. We accomplished a 2-D protein gel analysis to compare expression profiles of the MP2 strain and the 1A680 standard strain after salt and ethanol stress. The MP2 strain shows changes in productions of some energy metabolism enzymes and flagellin protein. We conclude that yxkO is a regulatory gene, whose product has a pleiotropic effect on many of cell functions.
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Effect of knock out of yxkO gene on environmental stress adaptation in genus Bacillus
Tkadlec, Jan ; Lichá, Irena (advisor) ; Krásný, Libor (referee)
We have previously characterized a Bacillus subtilis mutant defective in growth and osmoadaptation under limited K+ concentrations. In this mutant, the yxkO gene encoding a putative ribokinase is disrupted. This gene is supposed to belong to the sigma B operon and its expression is induced after osmotic, heat and ethanol shock. In comparison to the wild type, this mutation causes pleiotropic changes in host phenotype. In addition to its osmosensitivity, the mutant differs in cell shape, motility and ability to produce endospores. Our goal was to focus on manifestations of the mutation in the yxkO gene in other bacteria of the genus Bacillus. Using plasmid pMUTIN4 we have prepared mutants with disruptions of this gene derived from Bacillus amyloliquefaciens and Bacillus subtilis subsp. spizizenii strains differing in the yxkO surroundings and in the level of laboratory domestication. As in the previous study (with laboratory strain Bacillus subtilis 168) we demonstrate impaired ability of the mutant strain derived from Bacillus amyloliquefaciens to grow in potassium limitation and osmotic shock. We have studied this phenomenon at the level of the growth dynamics of the bacterial culture. We have also detected an increased sensitivity of the strain derived from Bacillus amyloliquefaciens to...
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General stress response in Staphylococcus aureus and its role in adaptation to hyperosmotic stress
Kotková, Hana ; Lichá, Irena (advisor) ; Seydlová, Gabriela (referee)
Hyperosmotic stress induces a stress reponse in a halotolerant bacteria Staphylococcus aureus that helps it to survive even the osmotic conditions that are inhibiting for most of the bacteria. Stress responses of S. aureus include a general stress response that activates rapidly on a wide range of stresses and is ensured by expression of genes induced by an alternative sigma B subunit of RNA polymerase (SigB), and more specific responses to hyperosmotic stress associated with transporters of potassium and transporters of compatible solutes. Also, some virulence factors (such as the adhesive Ebh protein) allow S. aureus to survive hyperosmotic stress within the host, thereby helping to colonize it. It is currently known that the general stress response directly and indirectly participates in the specific stress adaptation through the Kdp transport system for potassium (Kdp transporter) and transporters of compatible solutes (PutP and OpuD). Expression of the Kdp transporter and the large S. aureus Ebh protein is SigB dependent, via Agr or ArlRS virulence regulator systems. The formation of a biofilm, in which SigB is significantly involved, may also enable to colonize host niches with low water activity. Hyperosmotic stress by triggering SigB initiates a complex response that is associated not only...
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Effect of knock out of yxkO gene on environmental stress adaptation in genus Bacillus
Tkadlec, Jan ; Lichá, Irena (advisor) ; Krásný, Libor (referee)
We have previously characterized a Bacillus subtilis mutant defective in growth and osmoadaptation under limited K+ concentrations. In this mutant, the yxkO gene encoding a putative ribokinase is disrupted. This gene is supposed to belong to the sigma B operon and its expression is induced after osmotic, heat and ethanol shock. In comparison to the wild type, this mutation causes pleiotropic changes in host phenotype. In addition to its osmosensitivity, the mutant differs in cell shape, motility and ability to produce endospores. Our goal was to focus on manifestations of the mutation in the yxkO gene in other bacteria of the genus Bacillus. Using plasmid pMUTIN4 we have prepared mutants with disruptions of this gene derived from Bacillus amyloliquefaciens and Bacillus subtilis subsp. spizizenii strains differing in the yxkO surroundings and in the level of laboratory domestication. As in the previous study (with laboratory strain Bacillus subtilis 168) we demonstrate impaired ability of the mutant strain derived from Bacillus amyloliquefaciens to grow in potassium limitation and osmotic shock. We have studied this phenomenon at the level of the growth dynamics of the bacterial culture. We have also detected an increased sensitivity of the strain derived from Bacillus amyloliquefaciens to...
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Study of the impact of physical and chemical stress to development of mutator phenotype in Bacillus subtilis
Šoberová, Tereza ; Lichá, Irena (advisor) ; Schierová, Michaela (referee)
In a bacterium's environment, life conditions are subject to constant changes. One of the proposed mechanisms of adaptation to these changes is the increase in mutation rate. Bacterial mutability is generally kept very low by action of various mechanisms of control and repair, one of the most important ones being the Mismatch Repair, which is the master regulator of genetic stability of organisms. When its function is impaired, larger amounts of mutations occur in cells. In adverse conditions, these might be beneficial for cells' adaptation. The role of these repair mechanisms in adaptive processes in Bacillus subtilis has not yet been definitely resolved. The previous work in our lab focused on establishing an experimental system to measure the extent of mutagenesis in B. subtilis, and the influence of several stresses on mutation rate was assessed. No significant increase in mutability was found to be triggered by nutrient limitation in stationary growth phase, hyperosmotic stress or increased cultivation temperature. Furthermore, a system to monitor the expression of mismatch repair proteins was constructed, which has not revealed significant differences between stressed and nonstressed growth conditions. This thesis follows the results of previous experiments, expanding the range of stresses...
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Role of the yxkO gene of Bacillus subtilis in responce to environmental stress.
Petrovová, Miroslava ; Lichá, Irena (advisor) ; Nešvera, Jan (referee)
ROLE OF THE YXKO GENE OF BACILLUS SUBTILIS IN RESPONCE TO ENVIRONMENTAL STRESS Abstract Mutation of the yxkO gene, which encodes a putative ribokinase and belongs to the σB general stress response regulon, leads to reduced salt tolerance under potassium limitation in Bacillus subtilis. The biological function of the yxkO gene has not been determined yet, but it may be involved in the high affinity potassium uptake system, which has been described in Escherichia coli in contrast to Bacillus subtilis. Our goal was to describe another features of a mutant in the yxkO gene and to try to propose the role of this gene. Using the integration vector pMutin4, we prepared a Bacillus subtilis strain MP2 with a yxkO gene inactivation. The MP2 strain displays limited growth in a rich medium and it is a sensitive strain to tetracycline. Furthermore, this strain is unable to form endospores and the cells are longer, which indicates a septum formation defect. We accomplished a 2-D protein gel analysis to compare expression profiles of the MP2 strain and the 1A680 standard strain after salt and ethanol stress. The MP2 strain shows changes in productions of some energy metabolism enzymes and flagellin protein. We conclude that yxkO is a regulatory gene, whose product has a pleiotropic effect on many of cell functions.
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