Structural characterization of a novel bacterial ESCRT-III protein in E. coli

Presenting author: Anja Heddier

Forschungszentraum Jülich GmbH, ERC-3 Structure Biology, Wilhelm-Johnen-Straße, 52425 Jülich [DE], a.heddier@fz-juelich.de

Author(s):
Anja Heddier, Benedikt Junglas, Ilona Ritter, Carsten Sachse

The structures and functions of endosomal sorting complexes required for transport (ESCRT)-III proteins in bacteria, such as PspA and Vipp1, have been intensively studied in recent years. In E. coli, an additional potential PspA-homolog, YjfJ, has been recently identified while a biochemical, structural and functional characterization is entirely lacking. Here we show that YjfJ from Escherichia coli is a bona fide member of bacterial ESCRT-III proteins. Using cryo-EM, we solved eight structures of YjfJ helical filaments to a resolution of 3.0 to 4.0 Å as well as two structures of YjfJ in presence of membranes at 4.4 and 6.0 Å. In these structures YjfJ monomers adopt the typical ESCRT-III fold as well as extensive plasticity typical for bacterial ESCRT-III proteins. Our data also revealed that apo state YjfJ polymers are very similar to apo state PspA polymers, whereas they change to Vipp1-like polymers upon lipid reconstitution. Preliminary functional data suggest that YjfJ and PspA may exhibit complementary functions in E. coli, where YjfJ may play a critical role in maintaining the membrane fluidity under cold (stress) conditions. The characterization of YjfJ will help to understand the evolution of ESCRT-III proteins in bacteria as well as membrane remodeling in E. coli.

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