How Genetic Mutation Restricts Mitochondria

 Mitochondria are double-membrane-bound organelle that is considered as a powerhouse of the cell as it generates energy in the form of ATP by using nutrients from food and oxygen. Without mitochondria, higher animals would likely not exist because their cells would only be able to obtain energy from anaerobic respiration (in the absence of oxygen), a process much less efficient than aerobic respiration. Mitochondria help in producing many metabolic products and cofactors which in turn are important for the functioning of many enzymes.  So, if Defect in mitochondria can lead to, diseases. Defective mitochondria lead above all to diseases of tissues and organs that demand high levels of energy. Therefore they often affect the nervous system, the heart or the skeletal muscles.

A new study led by researchers of the University of Freiburg have identified the mutation which interferes with the functioning of the mitochondria.The team consists of  Dr. Nora Vögtle, head of an Emmy Noether junior research group at the Institute of Biochemistry and Molecular Medicine of the University of Freiburg, together with her team and in cooperation with pediatricians from Europe, Australia, and the USA.This mutation obstructs the powerhouses of cells i.e. mitochondria. this mutation causes harmless infection in early childhood but afterward leads to severe disease and consequently brain lose its ability to maintain control of key bodily functions, including motor functions.

For their research, researchers did the Genetic analysis of the genome of affected patients and their families from three different continents and found that there was a specific gene which was always changed by an inherited mutation in the patients. This gene supplies the blueprint for a protein that is needed in the mitochondria. Here, this protein removes signal attachments, known as presequences, which are needed to import most of the mitochondrial proteins from the cell fluid. Therefore, it is termed as Mitochondrial Presequence Protease (MPP).

During their research, the team showed that the genetic changes in the MPP gene lead to a protein with impaired functioning. Due to damage to this gene, it cannot cleave the presequences efficiently which in turn results in accumulation of immature proteins in the mitochondria. The researcher used baker’s yeast as a model organism for their study and introduced the same disease-causing mutations in yeast MPP, which is related to the human gene and studied the resulting consequences on the work processes in the mitochondria.

“Sadly we have not yet been able to save any of the sick children with our findings,” says Vögtle, adding, “However without this fundamental explanation of pathological mechanisms no therapeutic approaches could be developed. We hope that our work will lead to the development of effective therapies in the long term.”