Scientists have cracked a molecular code that may open the way to destroying or correcting defective gene products, such as those that cause genetic disorders in humans.

The code determines the recognition of RNA molecules by a superfamily of RNA-binding proteins called pentatricopeptide repeat (PPR) proteins.

When a gene is switched on, it is copied into RNA. This RNA is then used to make proteins that are required by the organism for all of its vital functions. If a gene is defective, its RNA copy and the proteins made from this will also be defective. This forms the basis of many terrible genetic disorders in humans.

RNA-binding PPR proteins could revolutionise the way we treat disease. Their secret is their versatility - they can find and bind a specific RNA molecule, and have the capacity to correct it if it is defective, or destroy it if it is detrimental. They can also help ramp up production of proteins required for growth and development.

The new paper in PLOS Genetics describes for the first time how PPR proteins recognise their RNA targets via an easy-to-understand code. This mechanism mimics the simplicity and predictability of the pairing between DNA strands described by Watson and Crick 60 years ago, but at a protein/RNA interface.