5m3n
From Proteopedia
HTRA2 wild-type structure
Structural highlights
Disease[HTRA2_HUMAN] Defects in HTRA2 are the cause of Parkinson disease type 13 (PARK13) [MIM:610297]. A complex neurodegenerative disorder characterized by bradykinesia, resting tremor, muscular rigidity and postural instability, as well as by a clinically significant response to treatment with levodopa. The pathology involves the loss of dopaminergic neurons in the substantia nigra and the presence of Lewy bodies (intraneuronal accumulations of aggregated proteins), in surviving neurons in various areas of the brain.[1] [2] Function[HTRA2_HUMAN] Serine protease that shows proteolytic activity against a non-specific substrate beta-casein. Promotes or induces cell death either by direct binding to and inhibition of BIRC proteins (also called inhibitor of apoptosis proteins, IAPs), leading to an increase in caspase activity, or by a BIRC inhibition-independent, caspase-independent and serine protease activity-dependent mechanism. Cleaves THAP5 and promotes its degradation during apoptosis. Isoform 2 seems to be proteolytically inactive.[3] [4] Publication Abstract from PubMedHtrA2 (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 degrees 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. Molecular motion regulates the activity of the Mitochondrial Serine Protease HtrA2.,Merski M, Moreira C, Abreu RM, Ramos MJ, Fernandes PA, Martins LM, Pereira PJB, Macedo-Ribeiro S Cell Death Dis. 2017 Oct 12;8(10):e3119. doi: 10.1038/cddis.2017.487. PMID:29022916[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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