Dr Susan Gottesman - Centre for Cancer Research, Bethesda
Kat - Hereís Susan Gottesman from the Centre for Cancer Research in Bethesda, Maryland, whoís an expert on bacterial RNAs. I asked her to explain more about how small RNAs can control the activity of genes in bacteria.
Susan - So, in parallel both in bacteria and humans, some of them have the ability to decide which of the messengers actually get translated into the protein machinery. So they pair with the messages, and then can change their fate, so they can make them disappear from the cell when they otherwise would be there. They can make them more active than they would otherwise be. And so, the cell has a capacity for sending in new signals to these small RNAs which are then regulating these much bigger messages and thatís important for development, itís important for cancer, important for disease, itís clearly important for bacteria to respond in a proper way to their host, and cause disease.
Kat - So, how are these small RNAs made?
Susan - So, thatís a little bit different between bacteria and animals because animal cells have a very complicated process. In the bacteria, they look just like some of the other genes. They have promoters, they're made of small pieces, and then they fold up and they can work. In the higher animal cells they're made in the nucleus, they have to be folded up, they have to be cut, they have to be sent out of the nucleus, and then processed down. In each of those steps, in some place at which the cell can say, ďOkay, I donít really want this or I do want it now.Ē
Kat - And in bacteria that you study, what are these small RNAs up to? What sort of processes are they controlling?
Susan - Well, the more we study them, the more we find out about what they're doing. So, if I tell you what I know now, thereíll be something new. We know they regulate whether the bacteria can swim from here to there. They regulate whether the bacteria have enough iron inside them to grow properly and how it gets that iron. They regulate whether the bacteria know to continue growing or stop growing so, almost everything. Every decision the bacteria has to make, and bacteria have to make a lot of decisions, the RNAs are in there, sticking in their two cents.
Kat - And what do we know about how this system has evolved because RNA and DNA kind of growing up in parallel?
Susan - Thatís really a very interesting question and I donít have an answer to it, so it's one of the things that I really like to play with, trying to figure out where these RNAs [came from] Ė are they ancient or are they newly evolving? They are evolving quickly. So, I think now that we know that they're there, we know where to look for them, we can start to understand what they do in the more complex behaviours. Letís just stay in the world of bacteria, how the bacteria interacts with its host, how it causes the disease, did that bacteria ever send RNAs to talk to the animal cells or vice versa. A lot of those things that we think would be really interesting that we donít know about yet. So, lots yet to look at.
Kat - That was Dr Susan Gottesman from the Centre for Cancer Research.