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Title: Molecular motion regulates the activity of the Mitochondrial Serine Protease HtrA2.
Authors: Merski, Matthew
Moreira, Cátia
Abreu, Rui M. V.
Ramos, Maria João
Fernandes, Pedro A.
Martins, L. Miguel
Pereira, Pedro José Barbosa
Macedo-Ribeiro, Sandra
First Published: 12-Oct-2017
Publisher: Nature Publishing Group for Associazione Differenziamento e Morte Cellulare
Citation: Cell Death and Disease, 2017, 8 (10), e3119
Abstract: HtrA2 (high-temperature requirement 2) is a human mitochondrial protease that has a role in apoptosis and Parkinson's disease. The structure of HtrA2 with an intact catalytic triad was determined, revealing a conformational change in the active site loops, involving mainly the regulatory LD loop, which resulted in burial of the catalytic serine relative to the previously reported structure of the proteolytically inactive mutant. Mutations in the loops surrounding the active site that significantly restricted their mobility, reduced proteolytic activity both in vitro and in cells, suggesting that regulation of HtrA2 activity cannot be explained by a simple transition to an activated conformational state with enhanced active site accessibility. Manipulation of solvent viscosity highlighted an unusual bi-phasic behavior of the enzymatic activity, which together with MD calculations supports the importance of motion in the regulation of the activity of HtrA2. HtrA2 is an unusually thermostable enzyme (TM=97.3 °C), a trait often associated with structural rigidity, not dynamic motion. We suggest that this thermostability functions to provide a stable scaffold for the observed loop motions, allowing them a relatively free conformational search within a rather restricted volume.
DOI Link: 10.1038/cddis.2017.487
ISSN: 2041-4889
eISSN: 2041-4889
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: Copyright © the authors, 2017. This is an open-access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Description: Supplementary Information accompanies this paper on Cell Death and Disease website (
Appears in Collections:Published Articles, Dept. of Molecular and Cell Biology

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