Purinergic control of lysenin’s transport and voltage-gating properties
| Autor: | Daniel Fologea, Philip Belzeski, Nisha Shrestha, Charles B. Hanna, Paul Carnig, Sheenah Bryant, Samuel Kosydar |
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| Rok vydání: | 2016 |
| Předmět: |
0301 basic medicine
Adenosine monophosphate Patch-Clamp Techniques Lipid Bilayers Gating Ion Channels 03 medical and health sciences Cellular and Molecular Neuroscience chemistry.chemical_compound Adenosine Triphosphate Animals Molecular Biology Ion channel Toxins Biological Purinergic receptor Cooperative binding Cell Biology Ligand (biochemistry) Adenosine Monophosphate Adenosine Diphosphate Protein Transport Adenosine diphosphate 030104 developmental biology chemistry Biochemistry Biophysics Original Article Ion Channel Gating Adenosine triphosphate |
| Zdroj: | Purinergic Signalling. 12:549-559 |
| ISSN: | 1573-9546 1573-9538 |
| Popis: | Lysenin, a pore-forming protein extracted from the coelomic fluid of the earthworm Eisenia foetida, manifests cytolytic activity by inserting large conductance pores in host membranes containing sphingomyelin. In the present study, we found that adenosine phosphates control the biological activity of lysenin channels inserted into planar lipid membranes with respect to their macroscopic conductance and voltage-induced gating. Addition of ATP, ADP, or AMP decreased the macroscopic conductance of lysenin channels in a concentration-dependent manner, with ATP being the most potent inhibitor and AMP the least. ATP removal from the bulk solutions by buffer exchange quickly reinstated the macroscopic conductance and demonstrated reversibility. Single-channel experiments pointed to an inhibition mechanism that most probably relies on electrostatic binding and partial occlusion of the channel-conducting pathway, rather than ligand gating induced by the highly charged phosphates. The Hill analysis of the changes in macroscopic conduction as a function of the inhibitor concentration suggested cooperative binding as descriptive of the inhibition process. Ionic screening significantly reduced the ATP inhibitory efficacy, in support of the electrostatic binding hypothesis. In addition to conductance modulation, purinergic control over the biological activity of lysenin channels has also been observed to manifest as changes of the voltage-induced gating profile. Our analysis strongly suggests that not only the inhibitor’s charge but also its ability to adopt a folded conformation may explain the differences in the observed influence of ATP, ADP, and AMP on lysenin’s biological activity. |
| Databáze: | OpenAIRE |
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