My next destination dates back to the 6th century, spawned by Birm, the leader of a Saxon tribe. Now Britain’s second largest city, Birmingham is the commercial centre of the Midlands. And it has more canals than Venice. So I take the opportunity to rendez-vous with Bryan Turner (University of Birmingham) at a lively canalside wine bar. Bryan recommends the Bardolino and we savour the warm cherry hues while he divulges the details of his scientific passion, histone acetylation. “Histones are the most common proteins in the nucleus, the proteins that package our DNA. They can be modified in many different ways influencing the way genes are expressed; whether they’re silent or active. Each type of cell has its own particular pattern of gene expression and this must be maintained as cells grow and divide. I guess I really want to understand how cells remember who they are”, he muses.

I ask him about these modifications, and how they work. He tells me about acetylation. First I need to understand that lysines within histones are positively charged. This is the basis of their attraction to negatively-charged DNA. “When the acetyl group is attached, it will remove the positive charge from that lysine, so you’ll get a loss of charge”. Biochemistry is so much better over a glass of wine. “By losing positive charges the histone tail region binds less strongly to the DNA, and that may free up the DNA so it can be transcribed, and the gene expressed”. But this isn’t the whole story. “We know it can work in more specific ways”, Bryan continues. “Another way is when you get acetylation of a particular lysine that creates a binding site for a particular protein, which will then bind to that histone tail, and in turn perhaps alter the way the gene is expressed”.

I’m surprised to learn that within the very wine I’m drinking, there are traces of the vitamin, nicotinamide. This is one of many dietary factors that can affect enzymes that add or remove acetyl groups, which in turn might alter gene activity. “Despite all the hype about genetic engineering”, Bryan explains, “it is extremely hard to change the DNA sequence. It’s much easier to change the behaviour of an enzyme”. He tells me about histone deacetylases, enzymes that remove acetyl groups from histones. Drugs that inhibit these enzymes are under trial as a potential cancer treatment. Remarkably, one deacetylase inhibitor and anti-cancer agent, butyric acid, occurs naturally in the gut, where it is produced by friendly bacteria. The amount of butyric acid and related compounds produced by these bacteria, is influenced by diet. “This may be a reason why a diet with lots of green vegetables protects against colon cancer”, Bryan suggests.