Multiple mechanisms, roles and controls of K+ transport in <i>Escherichia coli</i>

Epstein, Wolfgang; Buurman, Ed T.; McLaggan, Debbie; Náprstek, J.

doi:10.1042/bst0211006

Cited by 87 publications

(63 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2C). To test whether the presence of K ϩ uptake systems in the E. coli KNabc strain impacted the antiport activity observed, assays were conducted with vesicles from transformants with the same plasmids in K ϩ -uptakedeficient E. coli TK2420, ⌬(kdpABC)trkD1⌬trkA (35). After correction for a low level of background activity in E. coli TK2420, the same antiport pattern and levels were observed in this host as in E. coli KNabc (data not shown).…”

Section: Cpa2mentioning

confidence: 91%

See 1 more Smart Citation

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

Fujisawa

Ito

Krulwich

2007

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

؉ (K ؉ ) efflux system from alkaliphilic Bacillus pseudofirmus OF4; and YhaTU, a K ؉ efflux system from Bacillus subtilis. Here a K ؉ /H ؉ antiport capacity was demonstrated for YhaTU, AmhMT, and KefFC in membrane vesicles from antiporter-deficient E. coli KNabc. The apparent K m for K ؉ was in the low mM range. The peripheral protein was required for YhaU-and KefC-dependent antiport, whereas both AmhT and AmhMT exhibited antiport. KefFC had the broadest range of substrates, using Rb ؉ ϷK ؉ >Li ؉ >Na ؉ . Glutathione significantly inhibited KefFC-mediated K ؉ /H ؉ antiport in vesicles. The inhibition was enhanced by NADH, which presumably binds to the KTN/RCK domain of KefC. The antiport mechanism accounts for the H ؉ uptake involved in KefFC-mediated electrophile resistance in vivo. Because the physiological substrate of AmhMT in the alkaliphile is NH4 ؉ , the results also imply that AmhMT catalyzes NH4 ؉ /H ؉ antiport, which would prevent net cytoplasmic H ؉ loss during NH4 ؉ efflux.

show abstract

Section: Cpa2mentioning

confidence: 91%

“…Although not studied here, electrophiles release the GSH inhibition, and the adducts formed between GSH and the electrophiles may activate antiport (35). Additional modulators that bind to KefF also are anticipated (see Discussion).…”

Section: Discussionmentioning

confidence: 99%

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

Fujisawa

Ito

Krulwich

2007

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…Therefore Kup seems to work to compensate for the decrease in the activity of TrkA at acid pH. The affinity of Kdp for potassium ions is higher than the other systems, and this system is thought to function in medium containing a very low amount of potassium ions (Epstein et al, 1993).…”

Section: How Do Bacteria Adapt To Changes In Cytoplasmic Ph?mentioning

confidence: 99%

“…coli has four systems for increasing intracellular potassium ion concentrations, Kdp, TrkA, Kup, and TrkF (Epstein et al, 1993). The activity of the major system, TrkA, declines rapidly at acid pH.…”

Section: How Do Bacteria Adapt To Changes In Cytoplasmic Ph?mentioning

confidence: 99%

Bacterial strategies to inhabit acidic environments.

Kobayashi

Saito

Kakegawa

2000

J. Gen. Appl. Microbiol.

View full text Add to dashboard Cite

“…] (GIBCO-BRL)(45) was used for cell and vesicles assays of Tc resistance and transport, respectively; E. coli JM109 and CJ236 (New England Biochemical) were used for steps of the site-directed mutagenesis as described previously (40); and E. coli TK2420 (trkD1 Δ(trkA) Δ(kdpABC)5 kup), a K + -uptake-deficient triple mutant (46), was used for assays of Rb + uptake by right-side-out (RSO) vesicles. E. coli strains were routinely maintained and grown in LBK (47).…”

Section: Bacterial Strains and Growth Conditionsmentioning

confidence: 99%

Importance of the GP Dipeptide of the Antiporter Motif and Other Membrane-Embedded Proline and Glycine Residues in Tetracycline Efflux Protein Tet(L)

et al. 2005

View full text Add to dashboard Cite

Proline and glycine residues are well represented among functionally important residues in hydrophobic domains of membrane transport proteins and several critical roles have been suggested for them. Here, the effects of mutational changes in membrane-embedded proline and glycine residues of Tet(L) were examined, with a focus on the conserved GP 155,156 dipeptide of Motif C, a putative "antiporter motif". Mutation of Gly 155 to cysteine resulted in a mutant Tet(L) that bound its tetracycline-divalent metal (Tc-Me 2+ ) substrate but did not catalyze efflux or exchange of TcMe 2+ or catalyze uptake or exchange of Rb + which was used to monitor the coupling ion. These results support suggestions that this region is involved in the conformational changes required for translocation. Mutations in Pro 156 resulted in reduction (P156G) or loss (P156A or C) of Tc-Me 2+ efflux capacity. All three Pro 156 mutants exhibited a K + leak (monitored by 86 Rb + fluxes) that was not observed in wild type Tet(L). A similar leak was observed in a mutant in a membrane-embedded proline residue elsewhere in the Tet(L) protein (P175C) as well as in a P156C mutant of related antiporter Tet(K). These findings are consistent with roles proposed for membrane-embedded prolines in tight helix packing. Patterns of Tc-resistance conferred by additional Tet(L) mutants indicate important roles for another GP dipeptide in transmembrane segment (TMS) X as well as for membrane-embedded glycine residues in TMS XIII.Almost all transport proteins have membrane-embedded proline residues in some of the multiple α-helices that are a general feature of transporters (1). These residues are preferentially paired with glycine residues that are also found in abundance in TMS 1 of transporters (2,3). Membrane-embedded proline and glycine residues of transporters are hypothesized to promote helix kinks and swivels that play crucial roles in the conformational flexibility required for transport mechanisms (2-6). They are further hypothesized to have roles in helix packing and association (7-9). These hypotheses have been stunningly supported for the largest family of membrane transport proteins, the MFS, a family of structurally related transporters of prokaryotes and eukaryotes that includes uniporters, antiporters and symporters. The MFS comprises about a quarter of all transport proteins (10,11). The first three high resolution

show abstract

Multiple mechanisms, roles and controls of K+ transport in Escherichia coli

Cited by 87 publications

References 1 publication

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

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

Bacterial strategies to inhabit acidic environments.

Importance of the GP Dipeptide of the Antiporter Motif and Other Membrane-Embedded Proline and Glycine Residues in Tetracycline Efflux Protein Tet(L)

Contact Info

Product

Resources

About