If we want to be able to live comfortably on a space colony, our bodies must first become more resistant to weightlessness and cosmic radiation. A sumo peptide may offer a solution.

SUMO peptides are indispensable in living cells. They bind to proteins and thus direct all kinds of chemical processes in our body in the right direction. It now appears that SUMO (English abbreviation for Small Ubiquitin-like modifier) also plays an important role in how the human body deals with weightlessness.

benefit of astronauts
A recent study from the United States Oklahoma State University It shows how the cells of the body “feel” that there is no gravitational force on them and how the cells react to this state of weightlessness. This information could be very useful, as scientists frantically search for ways to keep astronauts healthy during future space missions, including protecting them from harmful cosmic rays.

The “microgravity” of space triggers a specific type of pressure response within the cell. A research team led by molecular biologist Rita Miller investigated these protein processes and discovered that the protein SUMO modifier plays a key role in the process of cell adaptation to a state of weightlessness. The researchers animated the cells in the lab using a device developed by NASA, while using an advanced microscope to observe what changed at the molecular level in the cell.

Jack of all trades microscopically
“We know that under normal gravity, SUMO responds to stress in different ways. The peptide plays an important role in many processes at the cellular level, such as repairing DNA damage, regulating the cytoskeleton (the network of fibers and tubes that give a cell its rigidity, shape, and movement), gene transcription, managing cell division, and replacing outdated proteins,” explains Professor Miller. “But our study now shows for the first time that SOMO also plays a key role in the cell’s response to microgravity.”

Humans have three different SUMO peptides busy working in cells. They are small: they consist of only about a hundred amino acids and are mainly found in the cell nucleus. Science is learning more and more about how this type of profession works, for example about the role SUMO plays in the development of cancer. SUMO peptides stabilize enzymes and transport proteins in and out of the cell nucleus by binding to specific proteins. This conjugation and uncoupling process is the result of a series of enzymatic reactions. Scientists call these modifications SUMOylation or deSUMOylation.

Weightless yeast
SUMO can bond chemically to a protein in two ways: a non-covalent bond (in which no electrons are shared between the binding partners) and a covalent bond (in which there are one or more common pairs of electrons). The researchers looked under a microscope at both types of interactions within yeast cells, which are often used to study cell processes. Half of the cells analyzed were the result of six cell divisions under normal terrestrial conditions, while the other half were born from yeast cells after six divisions in simulated microgravity, as in space.

MORE ACTIVE SUMO
The specific correlations of SUMO peptides and the amount of protein expression were compared for both groups of yeast cells. During weightlessness, sumo is shown to be more active than normal gravity. The researchers counted at least 37 proteins that are more than 50 percent associated with sumo in microgravity. These included proteins involved in DNA repair. And let this be extremely important in space because of the radiation damage caused by cosmic rays.

“SUMO can have a lot of different functions in the cell. We hope that our study will lead to a better understanding of the regulation of enzymatic cascade reactions in microgravity involving this particular peptide,” concludes Miller. A follow-up study is already planned and will address the possible adverse effect of a deficiency of SUMO peptides in the cell during weightlessness. The team wants to know if this degrades the functioning of certain proteins and to what extent this is harmful to the cell.