The importance of glycosylation for microbial evolution

Protein glycosylation is an important property of eukaryotic cells with manifold functions. Even in yeast cells, gene deletion mutants associated with protein glycosylation show various defects in protein quality control, cell proliferation and stress resistance. As such, the cellular protein glycosylation pathway is an important part of the regulatory machinery in yeast cells. Bacteria and yeasts have been used for numerous studies on molecular evolution and long-term adaptation, providing basic insights into the adaptive changes and flexibility of gene regulatory networks during environmental specialization. Nevertheless, specifically for eukaryotic microbes, the implications of long-term stress adaptation in context with compromised regulatory networks are not well characterized. In order to increase our understanding of the evolution of yeasts in stressful environments, with special emphasis on the importance of fully functional protein glycosylation, the evolvability of the biotechnologically relevant yeast Pichia pastoris will be analyzed. By parallel laboratory evolution of wild-type and glycosylation-mutant P. pastoris cells in stress and control environments, insights into the implications of protein glycosylation for their evolutionary potential will be acquired. An in-depth systems wide analysis of the adapted populations and the resulting insights into the molecular evolution of this non-conventional yeast will greatly extend our knowledge on the dynamics of regulatory networks and adaptation strategies of microbial cells. Additionally, the obtained data will provide valuable information for the establishment of in silico cellular models for future biotechnological research and lead to increased knowledge of fungal physiology.