The functional form of ClpP, the proteolytic component of ATP-dependent Clp proteases, is a hollow-cored particle composed of two heptameric rings joined face-to-face forming an aqueous chamber containing the proteolytic active sites. We have found that isolated human mitochondrial ClpP (hClpP) is stable as a heptamer and remains a monodisperse species (s(20,w) 7.0 S; M(app) 169, 200) at concentrations > or = 3 mg/ml. Heptameric hClpP has no proteolytic activity and very low peptidase activity. In the presence of ATP, hClpX interacts with hClpP forming a complex, which by equilibrium sedimentation measurements has a M(app) of 1 x 10(6). Electron microscopy confirmed that the complex consisted of a double ring of hClpP with an hClpX ring axially aligned on each end. The hClpXP complex has protease activity and greatly increased peptidase activity, indicating that interaction with hClpX affects the conformation of the hClpP catalytic active site. A mutant of hClpP, in which a cysteine residue was introduced into the handle region at the interface between the two rings formed stable tetradecamers under oxidizing conditions but spontaneously dissociated into two heptamers upon reduction. Thus, hClpP rings interact transiently but very weakly in solution, and hClpX must exert an allosteric effect on hClpP to promote a conformation that stabilizes the tetradecamer. These data suggest that hClpX can regulate the appearance of hClpP peptidase activity in mitochondria and might affect the nature of the degradation products released during ATP-dependent proteolytic cycles.
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Virulence
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National Key Laboratory of Agricultural Microbiology, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, China.
The emergence of antibiotic-resistant bacteria has attracted interest in the field of endolysins. Here, we analyzed the diversity of endolysins and identified a new endolysin, Ply2741, that exhibited broad-spectrum bactericidal activity. Our results demonstrated that Ply2741 could effectively eradicate multidrug-resistant gram-positive pathogens and .
View Article and Find Full Text PDFJ Neuroinflammation
January 2025
Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, USA.
The thrombolytic protease tissue plasminogen activator (tPA) is expressed in the CNS, where it regulates diverse functions including neuronal plasticity, neuroinflammation, and blood-brain-barrier integrity. However, its role in different brain regions such as the substantia nigra (SN) is largely unexplored. In this study, we characterize tPA expression, activity, and localization in the SN using a combination of retrograde tracing and β-galactosidase tPA reporter mice.
View Article and Find Full Text PDFBMJ
January 2025
Department of Neurology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China.
Objective: To assess whether intra-arterial tenecteplase administered after successful endovascular recanalisation improves outcomes in patients with acute arterial occlusion of the posterior circulation.
Design: Multicentre randomised controlled trial.
Setting: 31 hospitals in China, 24 January 2023 to 24 August 2023.
Open Biol
January 2025
Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus School of Medicine, Aurora, CO 80045, USA.
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View Article and Find Full Text PDFHuman amylin, called also islet amyloid polypeptide (hIAPP), is the principal constituent of amyloid deposits in the pancreatic islets. Together with hyperglycemia, hIAPP-derived oligomers and aggregates are important culprits in type 2 diabetes mellitus (T2DM). Preventing aggregation, and in particular inhibiting the formation and/or stimulating degradation of toxic amylin oligomers formed early in the process, may reduce the negative effects of T2DM.
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