Three two-component transporters with channel-like properties have monovalent cation/proton antiport activity

Fujisawa, Makoto; Ito, Masahiro; Krulwich, Terry A.

doi:10.1073/pnas.0703709104

Cited by 60 publications

(56 citation statements)

References 54 publications

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“…In EvoR2, bmrU and yhaU contain indels, therefore the YhaU/YhaT antiporter function, as well as potential multidrug resistance exerted by Bmr, is lost (Fujisawa et al, 2007). Hypothetical protein BmrU, however, may not be essential for this multidrug-resistance system (Petersohn et al, 1999;Petersohn et al, 2001), therefore it may be a phenotypically silent mutation.…”

Section: Discussionmentioning

confidence: 99%

“…The remaining mutated genes are bmrU, yhaU and sigV. bmrU is part of an operon-encoding multidrug transporter Bmr and regulator BmrR and is expressed, for example, under glucose starvation (Petersohn et al, 1999;Petersohn et al, 2001), yhaU encodes a K þ /H þ antiporter for K þ efflux (Fujisawa et al, 2007) and sigV encodes one of seven extracytoplasmic function (ECF) sigma factors and is related to cell envelope homeostasis and antibiotic resistance (Mascher et al, 2007;Hashimoto et al, 2009Hashimoto et al, , 2013Matsuoka et al, 2011).…”

Section: Whole-genome Sequencingmentioning

confidence: 99%

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Repeated triggering of sporulation in Bacillus subtilis selects against a protein that affects the timing of cell division

et al. 2013

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Bacillus subtilis sporulation is a last-resort phenotypical adaptation in response to starvation. The regulatory network underlying this developmental pathway has been studied extensively. However, how sporulation initiation is concerted in relation to the environmental nutrient availability is poorly understood. In a fed-batch fermentation set-up, in which sporulation of ultraviolet (UV)-mutagenized B. subtilis is repeatedly triggered by periods of starvation, fitter strains with mutated tagE evolved. These mutants display altered timing of phenotypical differentiation. The substrate for the wall teichoic acid (WTA)-modifying enzyme TagE, UDP-glucose, has recently been shown to be an intracellular proxy for nutrient availability, and influences the timing of cell division. Here we suggest that UDP-glucose also influences timing of cellular differentiation.

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Section: Discussionmentioning

confidence: 99%

Section: Whole-genome Sequencingmentioning

confidence: 99%

Repeated triggering of sporulation in Bacillus subtilis selects against a protein that affects the timing of cell division

et al. 2013

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“…Rather, it may increase the activity of KefC in two interdependent ways: first, by modulating the NADH pool (Fig. 6), since this nucleotide is believed to be an inhibitor of KefC (16), and second, by holding KefC KTN domains in the correct configuration to attain optimal activity (29,36).…”

Section: Discussionmentioning

confidence: 99%

“…Recently, we showed that GSH and GSX occupy overlapping binding pockets in KefC but that the additional steric bulk of GSX causes a significant conformational change, which results in activation of KefC (35). In addition, the KTN domain has a nucleotide binding site on a Rossman fold (36), and it has been suggested that KefC is inactivated when NADH is bound at this site (16). In many bacteria, including E. coli, regulation of Kef is still more complicated, as soluble KefB/KefC-binding proteins have been discovered (KefG and KefF, respectively) that are required to associate with KefB/KefC to allow full activation of these systems (29).…”

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confidence: 99%

KefF, the Regulatory Subunit of the Potassium Efflux System KefC, Shows Quinone Oxidoreductase Activity

et al. 2011

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Escherichia coli and many other Gram-negative pathogenic bacteria protect themselves from the toxic effects of electrophilic compounds by using a potassium efflux system (Kef). Potassium efflux is coupled to the influx of protons, which lowers the internal pH and results in immediate protection. The activity of the Kef system is subject to complex regulation by glutathione and its S conjugates. Full activation of KefC requires a soluble ancillary protein, KefF. This protein has structural similarities to oxidoreductases, including human quinone reductases 1 and 2. Here, we show that KefF has enzymatic activity as an oxidoreductase, in addition to its role as the KefC activator. It accepts NADH and NADPH as electron donors and quinones and ferricyanide (in addition to other compounds) as acceptors. However, typical electrophilic activators of the Kef system, e.g., N-ethyl maleimide, are not substrates. If the enzymatic activity is disrupted by site-directed mutagenesis while retaining structural integrity, KefF is still able to activate the Kef system, showing that the role as an activator is independent of the enzyme activity. Potassium efflux assays show that electrophilic quinones are able to activate the Kef system by forming S conjugates with glutathione. Therefore, it appears that the enzymatic activity of KefF diminishes the redox toxicity of quinones, in parallel with the protection afforded by activation of the Kef system.

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“…The residual germination was very asynchronous, and some spores appeared to become phase dark before losing heat resistance (24). This GerN protein is a homolog of a widely distributed family of cation transporters (9) and has been demonstrated to mediate Na ϩ /H ϩ and Na ϩ / H ϩ -K ϩ antiport activity when expressed at a low level in Escherichia coli (21). Such GerN-mediated antiport activity is therefore apparently required for the germination response mediated by the GerI germinant receptor in B. cereus.…”

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confidence: 99%

The Bacillus cereus GerN and GerT Protein Homologs Have Distinct Roles in Spore Germination and Outgrowth, Respectively

Senior

Moir

2008

J Bacteriol

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The GerT protein of Bacillus cereus shares 74% amino acid identity with its homolog GerN. The latter is a Na ؉ /H ؉ -K ؉ antiporter that is required for normal spore germination in inosine. The germination properties of single and double mutants of B. cereus ATCC 10876 reveal that unlike GerN, which is required for all germination responses that involve the GerI germinant receptor, the GerT protein does not have a significant role in germination, although it is required for the residual GerI-mediated inosine germination response of a gerN mutant. In contrast, GerT has a significant role in outgrowth; gerT mutant spores do not outgrow efficiently under alkaline conditions and outgrow more slowly than the wild type in the presence of high NaCl concentrations. The GerT protein in B. cereus therefore contributes to the success of spore outgrowth from the germinated state during alkaline or Na ؉ stress.Bacillus cereus ATCC 10876 spores germinate in inosine or in L-alanine as sole germinants (5). They require both GerI and GerQ germinant receptors for germination in inosine as the sole germinant, whereas the GerL receptor is responsible for most of the response to L-alanine as the sole germinant, with a smaller contribution from the GerI receptor (3). The GerN protein is needed for successful inosine germination, as spores of a gerN mutant of B. cereus ATCC 10876 demonstrate a slow and abnormally ordered germination response in inosine as the sole germinant (24). The residual germination was very asynchronous, and some spores appeared to become phase dark before losing heat resistance (24). This GerN protein is a homolog of a widely distributed family of cation transporters (9) and has been demonstrated to mediate Na ϩ /H ϩ and Na ϩ / H ϩ -K ϩ antiport activity when expressed at a low level in Escherichia coli (21). Such GerN-mediated antiport activity is therefore apparently required for the germination response mediated by the GerI germinant receptor in B. cereus. The role of such an ion transport protein in germination remains unclear, especially as other germinant receptors in the same strain do not require a functional GerN protein; for example, the gerL-dependent alanine response is almost identical to that of the wild type in a gerN mutant (24). Both GerN and a closely related homolog are encoded in B. cereus ATCC 14579 (13) and in other members of the family, including Bacillus anthracis (17) and Bacillus thuringiensis (16). Both genes appear to be monocistronic, and their coding sequences are widely separated on the genome. We have called this second gerN-like gene gerT (19). An entirely different (spore coat) protein in B. subtilis has recently been called gerT (7), but that gene does not have a homolog in B. cereus, and as B subtilis does not carry an equivalent homolog of the B. cereus gerN or gerT gene, the nomenclature will not overlap. We describe here the spore germination and outgrowth phenotypes of mutants of B. cereus ATCC 10876 carrying an insertionally inactivated gerT gene. Resulting phenotypes s...

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Three two-component transporters with channel-like properties have monovalent cation/proton antiport activity

Cited by 60 publications

References 54 publications

Repeated triggering of sporulation in Bacillus subtilis selects against a protein that affects the timing of cell division

Repeated triggering of sporulation in Bacillus subtilis selects against a protein that affects the timing of cell division

KefF, the Regulatory Subunit of the Potassium Efflux System KefC, Shows Quinone Oxidoreductase Activity

The Bacillus cereus GerN and GerT Protein Homologs Have Distinct Roles in Spore Germination and Outgrowth, Respectively

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