Title
Mechanism of Amyloidogenesis of a Bacterial AAA+ Chaperone
Author
Sze Wah Samuel Chen, Jason Yau, Christopher Ing, Kaiyin Liu, Patrick Farber, Amy Won, Vaibhav Bhandari, Nareg Kara-Yacoubian, Thiago V. Seraphim, Nilmadhab Chakrabarti, Lewis E. Kay, Christopher M. Yip, Régis Pomès, Simon Sharpe, Walid A. Houry
Year
2016
Journal
Structure
Abstract
Amyloids are fibrillar protein superstructures that are commonly associated with diseases in humans and with physiological functions in various organisms. The precise mechanisms of amyloid formation remain to be elucidated. Surprisingly, we discovered that a bacterial Escherichia coli chaperone-like ATPase, regulatory ATPase variant A (RavA), and specifically the LARA domain in RavA, forms amyloids under acidic conditions at elevated temperatures. RavA is involved in modulating the proper assembly of membrane respiratory complexes. LARA contains an N-terminal loop region followed by a β-sandwich-like folded core. Several approaches, including nuclear magnetic resonance spectroscopy and molecular dynamics simulations, were used to determine the mechanism by which LARA switches to an amyloid state. These studies revealed that the folded core of LARA is amyloidogenic and is protected by its N-terminal loop. At low pH and high temperatures, the interaction of the N-terminal loop with the folded core is disrupted, leading to amyloid formation.
Instrument
J-810
Keywords
Circular dichroism, Protein denaturation, Thermal stability, Secondary structure, Aggregation, Biochemistry