New Mechanism Discovered in Meiosis

A research group headed by molecular biologist Dr. Andrea Pichler from the Max Planck Institute of Immunobiology and Epigenetics in Freiburg, Germany, has made an important discovery in meiosis research. Dr. Pichler and her group have identified a new mechanism that plays an important role in meiosis. The work was reported online on May 2, 2013 in Molecular Cell. Meiosis, also called reductional division, is a key process in sexual reproduction. It shuffles parental genetic material and thus guarantees genetic variety. In order to control various biological processes, cells are able to selectively alter properties of their proteins, such as their lifespan, activity level, binding partners, or localization of the proteins. This is accomplished, for example, by attaching one or more small ubiquitin-like modifier (SUMO) proteins. This takes place in three sequential enzyme-dependent steps. Scientists have assumed that the enzyme for step 2 was solely an intermediate. As the scientists in Freiburg have now discovered, the step-2 enzyme is itself modified by the SUMO protein and thereby alters how it functions. The surprising effect: the conventional activity of the enzyme is switched off by this change and instead, a new function is gained. It works together with the activated, unaltered enzyme in the formation of SUMO chains. If this effect is blocked, there are serious consequences: the protein structure (synaptonemal complex) that forms between the homologous chromosomes can no longer be established. A tiny amount – less than one percent – of the SUMO-modified step-2 enzyme is sufficient to form a normal protein structure. Researcher Dr. Helene Klug from Dr.