Gunka, Katrin

[["dc.bibliographiccitation.artnumber","758"],["dc.bibliographiccitation.journal","Frontiers in Microbiology"],["dc.bibliographiccitation.volume","5"],["dc.contributor.author","Stannek, Lorena"],["dc.contributor.author","Gunka, Katrin"],["dc.contributor.author","Care, Rachel A."],["dc.contributor.author","Gerth, Ulf"],["dc.contributor.author","Commichau, Fabian M."],["dc.date.accessioned","2018-11-07T10:02:18Z"],["dc.date.available","2018-11-07T10:02:18Z"],["dc.date.issued","2015"],["dc.description.abstract","The Gram-positive model bacterium Bacillus subtilis contains two glutamate dehydrogenase-encoding genes, rocG and gudB. While the rocG gene encodes the functional GDH, the gudB gene is cryptic (gudB(CR)) in the laboratory strain 168 due to a perfect 18 bp-long direct repeat that renders the GudB enzyme inactive and unstable. Although constitutively expressed the GudB(CR) protein can hardly be detected in B. subtilis as it is rapidly degraded within stationary growth phase. Its high instability qualifies GudB(CR) as a model substrate for studying protein turnover in B. subtilis. Recently, we have developed a visual screen to monitor the GudB(CR) stability in the cell using a GFP-GudB(CR) fusion. Using fluorescent microscopy we found that the G FP protein is simultaneously degraded together with GudB(CR). This allows us to analyze the stability of GudB(CR) in living cells. By combining the visual screen with a transposon mutagenesis approach we looked for mutants that show an increased fluorescence signal compared to the wild type indicating a stabilized GFP-GudB(CR) fusion. We observed, that disruption of the arginine kinase encoding gene mcsB upon transposon insertion leads to increased amounts of the GFP-GudB(CR) fusion in this mutant. Deletion of the cognate arginine phosphatase YwIE in contrast results in reduced levels of the GFP-GudB(CR) fusion. Recently, it was shown that the kinase McsB is involved in phosphorylation of GudB(CR) on arginine residues. Here we show that selected arginine-lysine point mutations of GudB(CR) exhibit no influence on degradation. The activity of McsB and YwIE, however, are crucial for the activation and inhibition, respectively, of a proteolytic machinery that efficiently degrades the unstable GudB(CR) protein in B. subtilis."],["dc.identifier.doi","10.3389/fmicb.2014.00758"],["dc.identifier.isi","000348706900001"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/11795"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/38197"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Frontiers Media Sa"],["dc.relation.issn","1664-302X"],["dc.rights","CC BY 4.0"],["dc.rights.uri","https://creativecommons.org/licenses/by/4.0"],["dc.title","Factors that mediate and prevent degradation of the inactive and unstable GudB protein in Bacillus subtilis"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","e66120"],["dc.bibliographiccitation.issue","6"],["dc.bibliographiccitation.journal","PLoS ONE"],["dc.bibliographiccitation.volume","8"],["dc.contributor.author","Gunka, Katrin"],["dc.contributor.author","Stannek, Lorena"],["dc.contributor.author","Care, Rachel A."],["dc.contributor.author","Commichau, Fabian M."],["dc.date.accessioned","2018-11-07T09:23:41Z"],["dc.date.available","2018-11-07T09:23:41Z"],["dc.date.issued","2013"],["dc.description.abstract","Soil bacteria like Bacillus subtilis can cope with many growth conditions by adjusting gene expression and metabolic pathways. Alternatively, bacteria can spontaneously accumulate beneficial mutations or shape their genomes in response to stress. Recently, it has been observed that a B. subtilis mutant lacking the catabolically active glutamate dehydrogenase (GDH), RocG, mutates the cryptic gudB(CR) gene at a high frequency. The suppressor mutants express the active GDH GudB, which can fully replace the function of RocG. Interestingly, the cryptic gudB(CR) allele is stably inherited as long as the bacteria synthesize the functional GDH RocG. Competition experiments revealed that the presence of the cryptic gudB(CR) allele provides the bacteria with a selective growth advantage when glutamate is scarce. Moreover, the lack of exogenous glutamate is the driving force for the selection of mutants that have inactivated the active gudB gene. In contrast, two functional GDHs are beneficial for the cells when glutamate was available. Thus, the amount of GDH activity strongly affects fitness of the bacteria depending on the availability of exogenous glutamate. At a first glance the high mutation frequency of the cryptic gudB(CR) allele might be attributed to stress-induced adaptive mutagenesis. However, other loci on the chromosome that could be potentially mutated during growth under the selective pressure that is exerted on a GDH-deficient mutant remained unaffected. Moreover, we show that a GDH-proficient B. subtilis strain has a strong selective growth advantage in a glutamate-dependent manner. Thus, the emergence and rapid clonal expansion of the active gudB allele can be in fact explained by spontaneous mutation and growth under selection without an increase of the mutation rate. Moreover, this study shows that the selective pressure that is exerted on a maladapted bacterium strongly affects the apparent mutation frequency of mutational hot spots."],["dc.description.sponsorship","Open-Access-Publikationsfonds 2013"],["dc.identifier.doi","10.1371/journal.pone.0066120"],["dc.identifier.isi","000321038800048"],["dc.identifier.pmid","23785476"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/9123"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/29637"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Public Library Science"],["dc.relation.issn","1932-6203"],["dc.rights","Goescholar"],["dc.rights.uri","https://goescholar.uni-goettingen.de/licenses"],["dc.title","Selection-Driven Accumulation of Suppressor Mutants in Bacillus subtilis: The Apparent High Mutation Frequency of the Cryptic gudB Gene and the Rapid Clonal Expansion of gudB(+) Suppressors Are Due to Growth under Selection"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]