Separate collection of mitochondrial debris

Cells sort the molecular debris before destroying it

Kirill Stasevich, Compulenta

Of all the proteins in the cell, the proteins of the mitochondria, the energy stations of the cell, in which the oxidation of nutrient molecules with oxygen and the transfer of the released energy into ATP molecules, break down faster than others and require replacement more often than others. Mitochondrial proteins live in conditions of constant oxidative stress due to oxygen radicals formed during oxygen manipulation. Damaged proteins must be disposed of in a timely manner, otherwise this molecular debris will spoil all biochemistry, and the consequences can be very deplorable.

It is believed that due to such proteins, aging is accelerated and neurodegenerative processes such as Alzheimer's and Parkinson's syndromes can even begin.

It is often easier for a cell to replace the entire mitochondria than its individual proteins, and in this case the process of mitophagy is triggered: the damaged mitochondria is enclosed in a special membrane bubble, with which the lysosome with splitting enzymes then merges, and the cell digests its own mitochondria.

But, as researchers from the Albert Ludwig University of Freiburg (Germany) found out, before that, molecular garbage is sorted: spoiled proteins of different types are collected in groups and only then digested. That is, the cell gets rid of some proteins faster, from others – slower.

The mitochondria in the cell are in continuous motion, they merge with each other and separate, forming an ever-changing mitochondrial network. According to the authors of the work in Nature Communications (Abeliovich et al., Involvement of mitochondrial dynamics in the segregation of mitochondrial matrix proteins during stationary phase mitophagy), this process is accompanied by the redistribution of proteins, so that damaged proteins are collected in one place. That is, as a result, something like a "garbage mitochondria" is obtained, into which all the most useless is dumped and which was sent to scrap. Those cells whose mitochondrial dynamics were disabled by mutation formed small, rounded mitochondria, and, importantly, no protein sorting occurred in this case.

Although experiments were conducted with yeast cells, this process is most likely going on in other eukaryotes – although this, of course, still needs to be checked.

It is possible that many diseases that are associated with abnormally functioning mitochondria are related precisely to the inability of cells to sort mitochondrial proteins, which simply does not leave completely healthy mitochondria in the cell.

Prepared based on the materials of the Albert Ludwig University of Freiburg: Mitochondria Separate Their Waste.

Portal "Eternal youth" http://vechnayamolodost.ru03.12.2013