[Myotox] Myotoxin discussion

Mon Nov 25 22:28:21 MST 2019

Thank you Harmen and greetings to all,

just a short note to let you know that regarding *liposomes *there is a 
group in Mexico already exploring permeabilization (calcein release) 
caused by this myotoxin - they are mostly focusing on 
ergosterol-containing liposomes (trying to approach fungal-like 
bilayers), but I though it is important that we are all aware of it, 
just to avoid any potential overlaps

I hope that this is OK with you, and that there may be different models 
which do not overlap with those liposome permeabilization studies

please allow me to copy this message also to my colleague Julian 
Fernandez, with whom we work together in the characterization of 
myotoxins in Costa Rica

kind regards,

Bruno

++++

On 25/11/2019 22:14, Steele, Harmen wrote:
> The SMA synthetic belts are highly negative.  In the electrostatic interactions with cytc we could never tell the difference between lipid and belt interactions.  To tell the differences in these interactions we had to us the biological belt, which are neutral in charge.  The SMA nanodiscs are uniform in size and shape when there is a membrane bound protein embedded. Without a membrane bound protein (pure lipid NDs), the nanodiscs are more homogeneous in size and shape.
>
> I have done some work using fluorescence anisotropy and various probes that embed in the lipid bilayers to examine the effect that various metal nanoparticles have on bilayer order.  The anisotropy gives us a way to study the degrees of freedom that a probe has in the lipid bilayer. These degrees of freedom can give us an idea of the order or disorder of a lipid bilayer.  By altering the lipid composition of a bilayer we could get an idea of what types of lipids are interacting with myotoxin resulting in leaky membranes.  I was thinking we start with a composition that resembles muscle and then alter the bilayer as we hone in on the specific lipid interactions.
>
> I don't think that nanodiscs would be the best model system to study this interaction. I believe that the belt protein provided a lateral pressure on the lipid bilayer that would inhibit and/or negate any changes a particle might have on the lipid bilayers packing order. I think that liposomes would be a more appropriate system.  Additionally, doing some studies with muscle cells would be appropriate too.
>
>
>   
> Best regards,
>   
> Harmen Steele, Ph.D.
> Postdoctoral Researcher
> harmen.steele at umontana.edu
>   
> +406 529 9669 - mobile
> Skype Me: harmensteele <callto://harmensteele/>
> Amateur Radio Call Sign: K9HBS
> I am a UM Ally <http://www.umt.edu/umallies/>
>   
> This email was sent using 95% recycled binary bits and 99.9% recycled electrons.
>   
>
> On 11/22/19, 4:55 PM, "Myotox on behalf of Borries Demeler" <myotox-bounces at biophysics.uleth.ca on behalf of demeler at gmail.com> wrote:
>
>      Hello all,
>      I am forwarding the information from Bruno to the mailing list so we
>      have a record there, including the attached papers so you all have
>      access to them.
>      
>      In addition: Tony/Mike and Paul: Amy has ~ 100 ul of pure myotoxin-II at
>      21 mg/ml (high concentration) available. It is in phosphate buffer as
>      far as I know. We could get that to you. If you need more, I am sure
>      Bruno could arrange another shipment.
>      
>      I also discussed the project with Harmen. He had a lot of interesting
>      ideas with respect on how to prepare nanodisks and membranes, and how
>      to check the interaction with Mytoxin-II with the membrane. He has been
>      working on a very similar project testing destruction of mitochondrial
>      membranes by cytochrome-C, Paul, this is the project we wanted to pursue
>      with you. Harmen sent some samples to you guys earlier, not sure if they
>      were ever analyzed, but perhaps we could pick this up again as well?
>      (and Paul, feel free to add this into the discussion for the CFI, since
>      it would be another excellent example for the collaboration between our
>      groups and justify the CMP-MAS probe).
>      
>      Harmen, I'm going to let you chime in and share your ideas on synthetic
>      belts, and various types of lipids that could be used for making
>      appropriate nanodiscs. Perhaps you could also find the source for the
>      muscle tissue membrane lipids you talked about, as well as some other
>      more readily available membrane systems we could try.
>      
>      Bruno indicated that most membranes would be affected by the toxicity
>      to some degree (what's different about the membranes of the snake's
>      toxin-producing glands/toxin-conducting tissues??)
>      
>      Thanks, -b.
>      
>      
>      
>      ----- Forwarded message from Bruno Lomonte <bruno.lomonte at ucr.ac.cr> -----
>      
>      Date: Fri, 22 Nov 2019 12:01:25 -0600
>      From: Bruno Lomonte <bruno.lomonte at ucr.ac.cr>
>      To: "Montina, Tony" <tony.montina at uleth.ca>, "Hazendonk, Paul" <paul.hazendonk at uleth.ca>, "Opyr, Michael"
>      	<michael.opyr at uleth.ca>, Borries Demeler <demeler at gmail.com>
>      Subject: Re: Research Collab Meeting
>      User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.9.1
>      
>      Thanks so much to all for your interest in exploring possibilities to
>      study the interaction of the myotoxin II with membranes.
>      
>      here attached is the paper in which some phospholipid compositions
>      were studied using liposomes, back in 1992
>      
>      there was also a follow up with an interesting observation about
>      potential auto-acylation of the myotoxin (also attached, 1995)
>      
>      codes for the crystal structe of the protein are:  1CLP and 1Y4L
>      
>      some info about the active region of the toxins here attached too (2001)
>      
>      happy to provide any further info, and of  course, protein, if you
>      find this project is viable and interesting
>      
>      special thanks to Borries for bridging our interests
>      
>      all the best,
>      
>      Bruno
>      
>
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-- 
Bruno Lomonte, Ph.D.
Instituto Clodomiro Picado
Universidad de Costa Rica
San José, 11501
COSTA RICA

bruno.lomonte at ucr.ac.cr
tel. +506  2511 7888
cel. +506  8392 0012

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