Membrane protein insertases of the YidC/Oxa1/Alb3 protein family

Every living cells consists of a unique set of proteins that fulfil the vital functions required for life. Some proteins function in the lipid bilayer that acts as a barrier to separate the inside and outside of a cell. These membrane proteins are extremely hydrophobic and unstable in an aqueous environment. Nevertheless, all proteins are synthesized on ribosomes within the cell and then are targeted to their final destination where they fold into their active conformation. How newly synthesized membrane proteins insert into the lipid bilayer is still poorly understood. A highly conserved mechanism of membrane protein insertion involves members of the YidC/Oxa1/Alb3 protein family. These membrane proteins consist of a core domain that fold into a hydrophilic groove that is supposed to allow a deep entry of newly synthesized membrane proteins into the lipid bilayer, and that guides their insertion and folding. In the thesis, we have examined how YidC interacts with ribosomes to coordinate these activities, and how it achieves specificity for its substrates which are mostly small membrane proteins. In addition, we have found a partner protein of YidC, namely YidD that supports the insertase function of YidC