Engineering Spider Glue
Scientists have identified what it is that can make spider webs so sticky, and the genes that spiders use to actually make them. Knowing this could bring us a step closer - maybe even a spider step - to making our own spider-based glues. Joining Chris Smith to explain how is Randy Lewis from the University of Wyoming...
Randy - Hello.
Chris - Welcome to The Naked Scientists. Tell us. So how are you, first of all, identifying these genes that spiders use to make their webs so sticky?
Randy - Well we took webs, about 100 of them actually, and washed the glue off of those webs; then we separated the proteins that make up that glue, and, using some chemical tricks, we were able to get some evidence of the proteins that were in there. And then we did a mass spectrometry study of all the peptides to find those and then used that information to go back to the spider itself and identify which were the genes that were involved in making these spider silk proteins.
Chris - I see. So because we know the genetic code, and we know what the protein sequence is that's in the spider stickiness that we've washed off the web, we can work out what gene sequences probably went into making those proteins? So if we then go back to the spider spinneret I guess - the structure that makes a silk - and ask, "can we find any genes like what the sequence would be in there?" then you got a chance of finding them?
Randy - Right. And especially in this case, because all the glue comes from a specialised gland. So you can actually just go directly to that gland and not worry about other kinds of genes because the predominant genes that are being made or being used in that gland are going to be for the spider silk glue.
Chris - And, presumably, the glue isn't just one particular protein. It must be a cocktail?
Randy - In this case, we believe it's two proteins actually and one of them looks more like a silk protein, the regular silk protein. The other one actually looks like what we call a mucin protein which makes up slime and snot. So, our combination is, is that it's really a silk and snot protein and the two of them together provide both strength and stickiness.
Chris - I think spiders will probably be mortified if they realize that you were calling their web stickiness as snotty. But is it possible to do what the spider does in its backend, in a test tube? In other words, can you borrow from biology? Can you copy this effectively?
Randy - We're in the process of defining whether we can do that or not, but we believe we can because the proteins are actually very simple and we need to find a system that can reproduce that. And we believe that if we can get those genes into some insect cells that grow in culture, that those cells should be able to produce the proteins with the sticky parts on them. The key here is, is that one of the proteins in particular has a whole lot of sugars put on it and you need to be able to have those sugars, we're fairly sure, in order to be able to get the stickiness. So we believe that using something like insect cells to start with, we can reproduce what the spider has and then actually test the material and see how well it performs.
Chris - And that's presumably because insect cells, evolutionary speaking are much closer to a spider than say, one of our cells would be. And so therefore, they're likely to have the right chemistry going on in the cell to add those sticky sugar molecules.
Randy - Right. And also, it turns out that insect cells are fairly easy to work with. So, we think that in inserting the genetic code from the spiders, also probably will fit better with the insect cells.
Chris - And if you are successful in making this happen, what will you be able to do with this glue?
Randy - Well, right now, we're not exactly sure, but we think that there certainly are possibilities for some biomedical applications, for closing on sutures, things like that, other places you might be able to use glue. We're also hopeful, and that remains to be seen, that you can use it in something like Epoxy and that is, put the two components separately won't be - won't give you that the real stickiness and that when we put the two together, you'll have a glue, and that's also very useful in a number of applications. And so, you can basically put it together and then have it be sticky and separately, they're just fine.
Chris - And lastly Randy, I understand that you are currently heading across Canada to rescue some goats. What's that all about?
Randy - Basically, a company we worked with, NECSI Biotechnologies, developed some transgenic goats that make the spider silk proteins in the milk and the company has - for all intent and purposes, gone under. And so, we're right now about 20 miles from the farm and this afternoon, we're going to go and prepare the goats. We'll pick them up tomorrow morning and bring them back to Wyoming, so we can preserve the genetics of those goats that have been made, because the company can't afford to keep them anymore. And we're going to move them down to Wyoming and keep the genes going and actually, use the milk to produce protein now or we can really get serious about looking at various kinds of products from it.