Cryo-EM structure of substrate-free E. coli Lon protease provides insights into the dynamics of Lon machinery

• Published in: Current research in structural biology 2019-11, Vol.1, p.13-20
• Main Authors: Botos, Istvan, Lountos, George T., Wu, Weimin, Cherry, Scott, Ghirlando, Rodolfo, Kudzhaev, Arsen M., Rotanova, Tatyana V., de Val, Natalia, Tropea, Joseph E., Gustchina, Alla, Wlodawer, Alexander
• Format: Article
• Language: English
• Subjects: AAA+ proteins; ATPase module; Cryo-EM; Lon protease
• ISSN: 2665-928X; 2665-928X
• DOI: 10.1016/j.crstbi.2019.10.001

Energy-dependent Lon proteases play a key role in cellular regulation by degrading short-lived regulatory proteins and misfolded proteins in the cell. The structure of the catalytically inactive S679A mutant of Escherichia coli LonA protease (EcLon) has been determined by cryo-EM at the resolution of 3.5 Å. EcLonA without a bound substrate adopts a hexameric open-spiral quaternary structure that might represent the resting state of the enzyme. Upon interaction with substrate the open-spiral hexamer undergoes a major conformational change resulting in a compact, closed-circle hexamer as in the recent structure of a complex of Yersinia pestis LonA with a protein substrate. This major change is accomplished by the rigid-body rearrangement of the individual domains within the protomers of the complex around the hinge points in the interdomain linkers. Comparison of substrate-free and substrate-bound Lon structures allows to mark the location of putative pivotal points involved in such conformational changes. In Brief The structure of the E. coli LonA protease was determined by cryo-EM. The unliganded hexameric complex adopts an open spiral quaternary structure. Upon interaction with substrate it likely undergoes a rigid-body conformational change resulting in a compact, closed-circle hexamer as reported in the Yersinia pestis Lon structure. [Display omitted] •E. coli LonA(S679A) protease adopts an open spiral quaternary structure.•This conformation might represent the resting state of the complex.•Upon substrate binding the open spiral will close into a circular hexamer.