Positively charged residues at the channel mouth boost single-file water flow

Hörner, Andreas; Siligan, Christine; Cornean, Alex; Pohl, Peter

doi:10.1039/c8fd00050f

Cited by 41 publications

(83 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…22,36,37,69,93 Even though the latter method relies on uo-rescence labeling of the channel, FCS is a very convenient, reliable and time efficient method which can be used in vivo as well as in vitro. The protein concentration in the plasma membrane of polarized or non-polarized cells, GUVs or free standing planar lipid bilayers can be directly assessed.…”

Section: G Protein Countingmentioning

confidence: 99%

Single-file transport of water through membrane channels

2018

Self Cite

View full text Add to dashboard Cite

Water at interfaces governs many processes on the molecular scale from electrochemical and enzymatic reactions to protein folding. Here we focus on water transport through proteinaceous pores that are so narrow that the water molecules cannot overtake each other in the pore. After a short introduction into the single-file transport theory, we analyze experiments in which the unitary water permeability, p f , of water channel proteins (aquaporins, AQPs), potassium channels (KcsA), and antibiotics (gramicidin-A derivatives) has been obtained. A short outline of the underlying methods (scanning electrochemical microscopy, fluorescence correlation spectroscopy, measurements of vesicle light scattering) is also provided. We conclude that p f increases exponentially with a decreasing number N H of hydrogen bond donating or accepting residues in the channel wall. The variance in N H is responsible for a more than hundredfold change in p f . The dehydration penalty at the channel mouth has a smaller effect on p f . The intricate link between p f and the Gibbs activation energy barrier, DG ‡ t , for water flow suggests that conformational transitions of water channels act as a third determinant of p f .

show abstract

Section: G Protein Countingmentioning

confidence: 99%

Single-file transport of water through membrane channels

2018

Self Cite

View full text Add to dashboard Cite

show abstract

“…( 1 ), which was already published in 2015. However, the analytical solution was only applied in our work group so far to calculate p f values of AQP1, GlpF, AqpZ, KcsA 38 , AQP4 53 and hSGLT1 3 . We attribute this to the fact that the Lambert function as part of the analytical solution is not implemented in common tools for stopped-flow data analysis.…”

Section: Discussionmentioning

confidence: 99%

“…PLs and LUVs are subjected to a hyperosmotic solution in a stopped-flow apparatus (SFM-300, Bio-Logic, Claix, France) at 4 °C. As previously described 3 , 4 , 38 , 53 , we monitor the intensity of scattered light at 90° at a wavelength of 546 nm. To calculate water permeability values from light scattering we use our recently found analytical solution 38 and three common approximations 25 , 41 , 42 as well as our new approximation all based on single-exponential functions with a time constant τ where depending on different models Π is equal to c out −1 , (c out – c in,0 ) −1 , c in,0 ·c out −2 or (c in,0 + c out )/(2· c out 2 ).…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Quantification of Water Flux in Vesicular Systems

Hannesschläger

Barta

Siligan

et al. 2018

Sci Rep

Self Cite

View full text Add to dashboard Cite

Water transport across lipid membranes is fundamental to all forms of life and plays a major role in health and disease. However, not only typical water facilitators like aquaporins facilitate water flux, but also transporters, ion channels or receptors represent potent water pathways. The efforts directed towards a mechanistic understanding of water conductivity determinants in transmembrane proteins, the development of water flow inhibitors, and the creation of biomimetic membranes with incorporated membrane proteins or artificial water channels depend on reliable and accurate ways of quantifying water permeabilities Pf. A conventional method is to subject vesicles to an osmotic gradient in a stopped-flow device: Fast recordings of scattered light intensity are converted into the time course of vesicle volume change. Even though an analytical solution accurately acquiring Pf from scattered light intensities exists, approximations potentially misjudging Pf by orders of magnitude are used. By means of computational and experimental data we point out that erroneous results such as that the single channel water permeability pf depends on the osmotic gradient are direct results of such approximations. Finally, we propose an empirical solution of which calculated permeability values closely match those calculated with the analytical solution in the relevant range of parameters.

show abstract

“…Plot of unitary water permeability of water channel proteins against the available number of hydrogen bonding sites in the single‐file region of pore walls. Adapted with permission from References . [Color figure can be viewed at wileyonlinelibrary.com]…”

Section: Mechanisms Of Water Transport Through Aquaporinsmentioning

confidence: 99%

Biomimetic and bioinspired membranes for water purification: A critical review and future directions

Wagh

Escobar

2019

Env Prog and Sustain Energy

View full text Add to dashboard Cite

Various types of channel proteins, broadly named porins, present in the cell membrane of gram‐negative bacteria have specific functionalities depending on their selectivity toward different nutrients or toward water. The high selectivity of porins has led to their incorporation into synthetic systems, in a field called biomimetics. An example is the addition of water channel proteins, or aquaporins, to polymeric separations membranes in order to enhance their performance in terms of selectivity and permeability. The concept of incorporating aquaporins into synthetic membranes has been studied for the last 10 years; however, there are still limitations such as costs, alignment into the membrane assembly, and scalability of membrane fabrication. Therefore, in recent years, there has been an increase in the study of synthesizing molecules with similar structure–function relationships of porins. These artificial channels attempt to mimic the biological porins, while being synthesized using simpler chemistry, being solvent compatible, and requiring less space on the membrane surface which helps to incorporate more channels into the membrane assembly. In summary, the future of biomimetic and bioinspired membranes depends on the design strategies, level of nature imitation, and the performance of these systems on a commercial scale. © 2019 American Institute of Chemical Engineers Environ Prog, 38:e13215, 2019

show abstract

Positively charged residues at the channel mouth boost single-file water flow

Abstract: Positively charged residues in the vicinity of the channel entrance or exit accelerate single-file water flow.

Cited by 41 publications

References 32 publications

Single-file transport of water through membrane channels

Single-file transport of water through membrane channels

Quantification of Water Flux in Vesicular Systems

Biomimetic and bioinspired membranes for water purification: A critical review and future directions

Contact Info

Product

Resources

About