Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
Morgan Chabanon
ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain; Universitat Politècnica de Catalunya-BarcelonaTech, Barcelona, Spain
Nikhil Walani
Universitat Politècnica de Catalunya-BarcelonaTech, Barcelona, Spain
Marino Arroyo
Universitat Politècnica de Catalunya-BarcelonaTech, Barcelona, Spain; Institute for Bioengineering of Catalonia, The Barcelona Institute of Science and Technology, Barcelona, Spain; Centre Internacional de Mètodes Numèrics en Enginyeria (CIMNE), Barcelona, Spain
Maria F Garcia-Parajo
ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain; ICREA, Barcelona, Spain
Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain; ICREA, Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain
The endoplasmic reticulum (ER)-resident protein TANGO1 assembles into a ring around ER exit sites (ERES), and links procollagens in the ER lumen to COPII machinery, tethers, and ER-Golgi intermediate compartment (ERGIC) in the cytoplasm (Raote et al., 2018). Here, we present a theoretical approach to investigate the physical mechanisms of TANGO1 ring assembly and how COPII polymerization, membrane tension, and force facilitate the formation of a transport intermediate for procollagen export. Our results indicate that a TANGO1 ring, by acting as a linactant, stabilizes the open neck of a nascent COPII bud. Elongation of such a bud into a transport intermediate commensurate with bulky procollagens is then facilitated by two complementary mechanisms: (i) by relieving membrane tension, possibly by TANGO1-mediated fusion of retrograde ERGIC membranes and (ii) by force application. Altogether, our theoretical approach identifies key biophysical events in TANGO1-driven procollagen export.
