Function and structure of specialised ribosomes in the testis

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All proteins in animals, plants and bacteria are made by a machine called the ribosome. This is one of the largest complexes in any cell, consisting of ~90 different components. Until recently it was thought that all ribosomes were the same, responsible for synthesising protein without exerting any regulatory activity. But fruit fly genetics and human diseases caused by mutations in the ribosome components suggest that not every component is essential all of the time. Mutations to specific components result in specific disease and developmental problems. For example, some components are important during development (e.g. mouse nervous system) and others during viral infection. So the current thinking is that some ribosomal components can be substituted by alternative components, allowing the ribosome to control which protein it makes. This is termed 'ribosome specialisation'. However, we do not yet understand how this works and what the functional consequences are.Our recent experiments and data from other researchers indicate that this specialisation of the ribosome is particularly common and extensive in the testis. In particular, we have seen differences in the components within the ribosomes in the fruit fly testis. Since protein production by the ribosome is particularly important during sperm production, we hypothesise that changes in ribosome composition are important during sperm production. Mutations in ribosomal components in the fruit fly result in male sterility. Therefore, understanding this ribosome specialisation has the potential to provide insight into the causes of male infertility in humans. This project aims to understand the composition of these specialised ribosomes in the testis and how the alterations in composition affect the production of protein. We will do this by understanding 1) how changes in composition affect the overall shape and structure of the ribosome; 2) how specialised ribosomes control the production of specific proteins; and 3) how the ribosome changes during sperm development in the testis. By shedding light into these two downstream effects we will be able understand the importance of specialised ribosomes. This project is a new collaboration between two experts in two different fields. This allows us to use the most appropriate and cutting-edge approaches to tackle the structure and function of specialised ribosome, including:- Fruit fly genetics: The fruit fly testis is a great model for studying specialised ribosomes because we can genetically modify the flies and dissect testes to generate enough material for sequencing and structural analysis. - Cryo-electron microscopy, which allows us to image ribosomes at a close-to-atomic resolution. - Next Generation Sequencing: To characterise how protein synthesis is affected by the different specialised ribosomes, we will use a novel sequencing approach to identify all the RNAs that the specialised ribosomes are decoding into protein. This is a high-throughput technique to look at all the protein production taking place in cells. This is a very novel area of research and this project has the potential to change the way we think about how protein production is controlled. It also has the potential to provide a basis for therapeutic targeting of a range of human diseases and disorders. A group of diseases are caused by mutations to the different ribosomal components, termed ribosomopathies, including Diamond-Blackfan disease. By understanding changes in ribosome composition and the functional importance of the different components we will shed light on the causes of these ribosomopathies.