THE METHOD by which β-barrel proteins are inserted into the membrane of mitochondria has been established by researchers from the University of Freiburg, Freiburg, Germany. The study not only answers a fundamental question in protein biochemistry, but provides new insights into the operations of mitochondria and the way in which chloroplasts and bacteria are formed.
Mechanisms and Previous Research
Understanding more about the way mitochondria function is important because of the crucial role they play in fuelling human cells. β-barrel proteins are vital in this fuelling process: they are components of protein import channels on the outer membrane of mitochondria, enabling protein molecules and ATP to be transported from the cytosol.
Previous research revealed that β-barrel membrane proteins are assembled by sheets created by strands of proteins extending in opposite directions that form a hollow cylinder by association of the first and last strand. Further research ascertained that the sorting and assembling machinery (SAM), necessary for the insertion of the barrel proteins, was located in the mitochondrial outer membrane.
Building on these findings, the researchers proved that it’s between the first and last strand of Sam50, the central subunit of SAM for the formation of β-barrel proteins, where the last strand of the new protein is introduced. The new strands of the new β-barrel were shown to be threaded piece by piece into Sam50’s lateral opening until the newly finished channel was released into the membrane.
The study therefore provides fresh knowledge about the formation and function of mitochondria. Additionally, it gives new understanding of the formation of chloroplasts and bacteria because mitochondria and the photosynthetic chloroplasts are derived from joint bacterial ancestors. This information could aid future research and treatments linked to the mitochondrial system.
James Coker, Reporter
For the source and further information about the study, click here.