Voltage-independent Adaptation of Mechanosensitive Channels in Escherichia coli Protoplasts

Koprowski, Piotr; Kubalski, Andrzej

doi:10.1007/s002329900410

Cited by 52 publications

(54 citation statements)

References 18 publications

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“…This suggests that the decline of activities was due to the lack of recovery of the adapted channels from their inactive state. We found previously that the recovery rate from an inactive state of the YggB channels was 72 and 95% following intervals of 60 and 120 s, respectively (18). In the experiment presented in Fig.…”

Section: Nisupporting

confidence: 51%

“…Even small changes in the position of the ␤-barrel strands may affect Ni 2ϩ binding to the histidine tags. We demonstrated previously that exposure of the cytoplasmic side of the MscS channels to 1 mg/ml Pronase almost entirely abolished their activities (18). We concluded that Pronase removed responsiveness of the channels to the membrane tension by disrupting the tension transmission mechanism responsible for the opening of the channel.…”

Section: Discussionmentioning

confidence: 68%

“…The difference in control traces arises from a different number of channels in each patch and also from the different pressure applied in each case. The rate of adaptation is inversely proportional to the suction (18), and accordingly, the highest rate of adaptation is observed in the control trace of experiment with the lowest suction applied (Fig. 3B).…”

Section: Conservation Of Yggb Domains Among Its Bacterial Homologues-mentioning

confidence: 77%

“…Single channel recordings were obtained from inside-out excised membrane patches, and the experimental procedure, including the equipment used and the application and measuring of suction, was the same as described earlier (18). Bath solution was 150 mM KCl, 400 mM sorbitol, 4 mM CaCl 2 , 1 mM MgCl 2 , 5 mM HEPES, pH 7.2, whereas the pipette solution was the same except that the sorbitol concentration was 300 mM.…”

Section: Methodsmentioning

confidence: 99%

“…The activities of the KefA and YggB channels recorded directly from the E. coli membrane are kinetically distinct; YggB shows inactivation during sustained pressure, i.e. adaptation (18), whereas KefA does not adapt to pressure (3,16). The YggB channels are more abundant than those of KefA, and their activities have been recorded after reconstitution of a purified protein in planar lipid bilayers (19,20), indicating that, similar to MscL, YggB senses membrane stress directly.…”

Section: Mechanosensitive (Ms)mentioning

confidence: 99%

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C Termini of the Escherichia coli Mechanosensitive Ion Channel (MscS) Move Apart upon the Channel Opening

Koprowski¹,

Kubalski

2003

Journal of Biological Chemistry

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Heptameric YggB is a mechanosensitive ion channel (MscS) from the inner membrane of Escherichia coli. We demonstrate, using the patch clamp technique, that cross-linking of the YggB C termini led to irreversible inhibition of the channel activities. Application of Ni 2؉ to the YggB-His 6 channels with the hexahistidine tags added to the ends of their C termini also resulted in a marked but reversible decrease of activities. Western blot revealed that YggB-His 6 oligomers are more stable in the presence of Ni 2؉ , providing evidence that Ni 2؉ is coordinated between C termini from different subunits of the channel. Intersubunit coordination of Ni 2؉ affecting channel activities occurred in the channel closed conformation and not in the open state. This may suggest that the C termini move apart upon channel opening and are involved in the channel activation. We propose that the as yet undefined C-terminal region may form a cytoplasmic gate of the channel. The results are discussed and interpreted based on the recently released quaternary structure of the channel. Mechanosensitive (MS)1 ion channels open upon membrane tension, and therefore they represent the simplest mechanosensors. MS channels have been implicated in many physiological processes from growth and cell volume regulation to hearing, blood pressure regulation, and pain sensation (reviewed in Ref. 1). Bacterial MS channels protect these cells against hypoosmotic shock. Two types of MS channels from the cytoplasmic membrane of Escherichia coli, MscL and MscS, play an essential role in the physiology of this bacterium, allowing the efflux of solutes from the cytoplasm when osmolarity of the external medium decreases (2-4). MscL, the large conductance MS channel, has been cloned (5), and a quaternary structure of its closed conformation has been determined (6). Based on this structure and the analysis of the channel gating, the open conformation has been predicted (7, 8) and experimentally confirmed (9, 10). Functional homologues of this channel have been found in other bacteria (11) and Archea (12), and structurally related protein from Neurospora has been also reported (13). The functional channel is a pentamer, and each subunit consists of two ␣-helical membrane-spanning domains TM1 and TM2 with both the C and N termini located in the cytoplasm (6). TM1s line the pore, and their hydrophobic residues form the primary, transmembrane gate (6, 14). It is postulated that there are two gates involved in the opening of the channel: the transmembrane and the cytoplasmic gates (7, 8) acting in accordance (15). The transmembrane gate is proposed to act as a pressure sensor, and upon application of pressure, this gate permits initial expansion of the channel without its full opening (7,8,10). It is proposed that the other, cytoplasmic gate, which allows full activation of the channel, is composed of five ␣-helical S1 segments of the cytoplasmic N termini being connected with TM1s via flexible linkers. According to the model, the applied pressure is transmitted to...

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Section: Nisupporting

confidence: 51%

Section: Discussionmentioning

confidence: 68%

Section: Conservation Of Yggb Domains Among Its Bacterial Homologues-mentioning

confidence: 77%

Section: Methodsmentioning

confidence: 99%

Section: Mechanosensitive (Ms)mentioning

confidence: 99%

See 3 more Smart Citations

C Termini of the Escherichia coli Mechanosensitive Ion Channel (MscS) Move Apart upon the Channel Opening

Koprowski¹,

Kubalski

2003

Journal of Biological Chemistry

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Bacterial ion channels and their eukaryotic homologues

Koprowski¹,

Kubalski²

2001

BioEssays

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Due to the relative ease of obtaining their crystal structures, bacterial ion channels provide a unique opportunity to analyse structure and function of their eukaryotic homologues. This review describes prokaryotic channels whose structures have been determined. These channels are KcsA, a bacterial homologue of eukaryotic potassium channels, MscL, a bacterial mechanosensitive ion channel and ClC0, a prokaryotic homologue of the eukaryotic ClC family of anion-selective channels. General features of their structure and function are described with a special emphasis on the advantages that these channels offer for understanding the properties of their eukaryotic homologues. We present amino-acid sequences of eukaryotic proteins related in their primary sequences to bacterial mechanosensitive channels. The usefulness of bacterial mechanosensitive channels for the studies on general principles of mechanosensation is discussed.

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From membrane tension to channel gating: A principal energy transfer mechanism for mechanosensitive channels

Zhang

2016

Protein Science

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Mechanosensitive (MS) channels are evolutionarily conserved membrane proteins that play essential roles in multiple cellular processes, including sensing mechanical forces and regulating osmotic pressure. Bacterial MscL and MscS are two prototypes of MS channels. Numerous structural studies, in combination with biochemical and cellular data, provide valuable insights into the mechanism of energy transfer from membrane tension to gating of the channel. We discuss these data in a unified two-state model of thermodynamics. In addition, we propose a lipid diffusion-mediated mechanism to explain the adaptation phenomenon of MscS.

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Voltage-independent Adaptation of Mechanosensitive Channels in Escherichia coli Protoplasts

Cited by 52 publications

References 18 publications

C Termini of the Escherichia coli Mechanosensitive Ion Channel (MscS) Move Apart upon the Channel Opening

C Termini of the Escherichia coli Mechanosensitive Ion Channel (MscS) Move Apart upon the Channel Opening

Bacterial ion channels and their eukaryotic homologues

From membrane tension to channel gating: A principal energy transfer mechanism for mechanosensitive channels

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