Requirement of a large K + -uptake capacity and of extracytoplasmic protease activity for protamine resistance of Escherichia coli

1997 ◽  
Vol 167 (2-3) ◽  
pp. 126-136 ◽  
Author(s):  
Stefan Stumpe ◽  
E. P. Bakker
Keyword(s):  
Escherichia Coli ◽  
Protease Activity ◽  
Uptake Capacity ◽  
K Uptake

scholarly journals N-Terminal Quarter Part of Tetracycline Transporter from pACYC184 Complements K+ Uptake Activity in K+ Uptake-Deficient Mutants of Escherichia coli and Vibrio alginolyticus.

1995 ◽  
Vol 18 (9) ◽  
pp. 1189-1193 ◽  
Author(s):  
Tatsunosuke NAKAMURA ◽  
Yasuhiro MATSUBA ◽  
Aya ISHIHARA ◽  
Tomomi KITAGAWA ◽  
Fumihiro SUZUKI ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Vibrio Alginolyticus ◽  
K Uptake ◽  
Uptake Activity

Potassium depletion improves myocardial potassium uptake in vivo

2004 ◽  
Vol 287 (1) ◽  
pp. C135-C141 ◽  
Author(s):  
Henning Bundgaard
Keyword(s):  
Uptake Rate ◽  
High Plasma ◽  
Potassium Depletion ◽  
Uptake Capacity ◽  
K Uptake ◽  
Impulse Generation ◽  
Uptake Rates ◽  
Clinical Interest ◽  
A Minor

Potassium depletion (KD) is a very common clinical entity often associated with adverse cardiac effects. KD is generally considered to reduce muscular Na-K-ATPase density and secondarily reduce K uptake capacity. In KD rats we evaluated myocardial Na-K-ATPase density, ion content, and myocardial K reuptake. KD for 2 wk reduced plasma K to 1.8 ± 0.1 vs. 3.5 ± 0.2 mM in controls ( P < 0.01, n = 7), myocardial K to 80 ± 1 vs. 86 ± 1 μmol/g wet wt ( P < 0.05, n = 7), increased Mg, and induced a tendency to increased Na. Myocardial Na-K-ATPase α2-subunit abundance was reduced by ∼30%, whereas increases in α1- and K-dependent pNPPase activity of 24% ( n = 6) and 13% ( n = 6), respectively, were seen. This indicates an overall upregulation of the myocardial Na-K pump pool. KD rats tolerated a higher intravenous KCl dose. KCl infusion until animals died increased myocardial K by 34% in KD rats and 18% in controls ( P < 0.05, n = 6 for both) but did not induce different net K uptake rates between groups. However, clamping plasma K at ∼5.5 mM by KCl infusion caused a higher net K uptake rate in KD rats (0.22 ± 0.04 vs. 0.10 ± 0.03 μmol·g wet wt−1·min−1; P < 0.05, n = 8). In conclusion, a minor KD-induced decrease in myocardial K increased Na-K pump density and in vivo increased K tolerance and net myocardial K uptake rate during K repletion. Thus the heart is protected from major K losses and accumulates considerable amounts of K during exposure to high plasma K. This is of clinical interest, because a therapeutically induced rise in myocardial K may affect contractility and impulse generation-propagation and may attenuate increased myocardial Na, the hallmark of heart failure.

scholarly journals Role of the PDZ Domains in Escherichia coli DegP Protein

2007 ◽  
Vol 189 (8) ◽  
pp. 3176-3186 ◽  
Author(s):  
Jack Iwanczyk ◽  
Daniela Damjanovic ◽  
Joel Kooistra ◽  
Vivian Leong ◽  
Ahmad Jomaa ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Protease Activity ◽  
Pdz Domain ◽  
Structural Features ◽  
Periplasmic Protein ◽  
Pdz Domains ◽  
Protease Domain ◽  
Interaction Domains ◽  
And Function

ABSTRACT PDZ domains are modular protein interaction domains that are present in metazoans and bacteria. These domains possess unique structural features that allow them to interact with the C-terminal residues of their ligands. The Escherichia coli essential periplasmic protein DegP contains two PDZ domains attached to the C-terminal end of the protease domain. In this study we examined the role of each PDZ domain in the protease and chaperone activities of this protein. Specifically, DegP mutants with either one or both PDZ domains deleted were generated and tested to determine their protease and chaperone activities, as well as their abilities to sequester unfolded substrates. We found that the PDZ domains in DegP have different roles; the PDZ1 domain is essential for protease activity and is responsible for recognizing and sequestering unfolded substrates through C-terminal tags, whereas the PDZ2 domain is mostly involved in maintaining the hexameric cage of DegP. Interestingly, neither of the PDZ domains was required for the chaperone activity of DegP. In addition, we found that the loops connecting the protease domain to PDZ1 and connecting PDZ1 to PDZ2 are also essential for the protease activity of the hexameric DegP protein. New insights into the roles of the PDZ domains in the structure and function of DegP are provided. These results imply that DegP recognizes substrate molecules targeted for degradation and substrate molecules targeted for refolding in different manners and suggest that the substrate recognition mechanisms may play a role in the protease-chaperone switch, dictating whether the substrate is degraded or refolded.

scholarly journals Cation transport in Escherichia coli. IX. Regulation of K transport.

1978 ◽  
Vol 72 (3) ◽  
pp. 283-295 ◽  
Author(s):  
D B Rhoads ◽  
W Epstein
Keyword(s):  
Escherichia Coli ◽  
Steady State ◽  
Cation Transport ◽  
Transport Systems ◽  
Energy Requirements ◽  
Protonmotive Force ◽  
K Uptake ◽  
Kinetics Of ◽  
K Transport ◽  
External K

Kinetics of K exchange in the steady state and of net K uptake after osmotic upshock are reported for the four K transport systems of Escherichia coli: Kdp, TrkA, TrkD, and TrkF. Energy requirements for K exchange are reported for the Kdp and TrkA systems. For each system, kinetics of these two modes of K transport differ from those for net K uptake by K-depleted cells (Rhoads, D. B. F.B. Walters, and W. Epstein. 1976. J. Gen. Physiol. 67:325-341). The TrkA and TrkD systems are inhibited by high intracellular K, the TrkF system is stimulated by intracellular K, whereas the Kdp system is inhibited by external K when intracellular K is high. All four systems mediate net K uptake in response to osmotic upshock. Exchange by the Kdp and TrkA systems requires ATP but is not dependent on the protonmotive force. Energy requirements for the Kdp system are thus identical whether measured as net K uptake or K exchange, whereas the TrkA system differs in that it is dependent on the protonmotive force only for net K uptake. We suggest that in both the Kpd and TrkA systems formation of a phosphorylated intermediate is necessary for all K transport, although exchange transport may not consume energy. The protonmotive-force dependence of the TrkA system is interpreted as a regulatory influence, limiting this system to exchange except when the protonmotive force is high.

scholarly journals Kup-mediated Cs+ uptake and Kdp-driven K+ uptake coordinate to promote cell growth during excess Cs+ conditions in Escherichia coli

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Ellen Tanudjaja ◽  
Naomi Hoshi ◽  
Yi-Hsin Su ◽  
Shin Hamamoto ◽  
Nobuyuki Uozumi
Keyword(s):  
Escherichia Coli ◽  
Cell Growth ◽  
K Uptake

scholarly journals Enhanced Net K+ Uptake Capacity of NaCl-Adapted Cells

1991 ◽  
Vol 95 (4) ◽  
pp. 1265-1269 ◽  
Author(s):  
Abd-Elrahem A. Watad ◽  
Moshe Reuveni ◽  
Ray A. Bressan ◽  
Paul M. Hasegawa
Keyword(s):  
Uptake Capacity ◽  
K Uptake

Escherichia coli Requires the Protease Activity of FtsH for Growth

2000 ◽  
Vol 380 (1) ◽  
pp. 103-107 ◽  
Author(s):  
Maithri M.K. Jayasekera ◽  
Susan K. Foltin ◽  
Eric R. Olson ◽  
Tod P. Holler
Keyword(s):  
Escherichia Coli ◽  
Protease Activity

Energetic consequences of multiple K + uptake systems in Escherichia coli

1986 ◽  
Vol 851 (2) ◽  
pp. 223-228 ◽  
Author(s):  
M.M. Mulder ◽  
M.J.Teixeira de Mattos ◽  
P.W. Postma ◽  
K. van Dam
Keyword(s):  
Escherichia Coli ◽  
K Uptake
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