Role of amphipathic transmembrane domains of single-spanning membrane proteins as determinants of their oligomeric state and subcellular localization.

• Applicant: Dr. Andreas Ernst
• Subject Area: Biochemistry
• Term: from 2014 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 258126872

Molecular dynamics simulations hinted at an unusual polar interface in mediating TMD-TMD interactions for p24 proteins (Contreras-Ernst et al., 2012). Other reports hint at the involvement of similar polar faces of TMDs in mediating localization to the Golgi and protein-protein interactions (Machamer et al., 1993; Dawson et al., 2002, 2003). Preliminary data that arose from bioinformatical analysis suggests that amphipathic TMD design is common for single-spanning membrane proteins and enriched in the early secretory pathway. With respect to the different models that attempt to explain specific localization of enzymes to the Golgi, I am planning to investigate whether the amphipathicity of TMDs is a crucial determinant in achieving this function. This hypothesis might combine all existing models, as ER-localization would be achieved via cytoplasmic retrieval signals of ER resident membrane proteins, while plasma membrane residents that also possess amphipathic TMDs would, due to their increased hydrophobic length, be excluded from Golgienzyme oligomers (TMD-partitioning model). Within the Golgi, kin recognition of Golgi enzymes would then be achieved by TMD-based interactions among oligomers. To study the contribution of amphipathic TMDs in homo- and heterooligomerization, a FRET-based proteoliposomal system and an in vivo BIrA-based biotinylation assay will be employed. The role of the amphipathic TMD of the respective candidate in its subcellular localization will be addressed by two-color, high-resolution STED nanoscopy.

• DFG Programme: Research Fellowships
• International Connection: USA
• Host: Professor Dr. James Rothman