Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA; Molecular, Cellular, and Developmental Biology Program, Division of Biology, Kansas State University, 338 Ackert Hall, Manhattan, KS 66506, USA. Electronic address:
Published: May 2020
AI Article Synopsis
Article Abstract
Proteasomes are multi-subunit protease complexes found in all domains of life. The maturation of the core particle (CP), which harbors the active sites, involves dimerization of two half CPs (HPs) and an autocatalytic cleavage that removes β propeptides. How these steps are regulated remains poorly understood. Here, we used the Rhodococcus erythropolis CP to dissect this process in vitro. Our data show that propeptides regulate the dimerization of HPs through flexible loops we identified. Furthermore, N-terminal truncations of the propeptides accelerated HP dimerization and decelerated CP auto-activation. We identified cooperativity in autocatalysis and found that the propeptide can be partially cleaved by adjacent active sites, potentially aiding an otherwise strictly autocatalytic mechanism. We propose that cross-processing during bacterial CP maturation is the underlying mechanism leading to the observed cooperativity of activation. Our work suggests that the bacterial β propeptide plays an unexpected and complex role in regulating dimerization and autocatalytic activation.
The ability of particles to transform absorbed energy into translational movements brings peculiar order into nonequilibrium matter. Connected together into a chain, these particles collectively behave completely differently from well-known equilibrium polymers. Examples of such systems vary from nanoscale to macroscopic objects.
In simulations, particles are traditionally treated as rigid platforms with variable sizes, shapes, and interaction parameters. While this representation is applicable for rigid core platforms, particles consisting of soft platforms (e.g.
The application of upconversion nanoparticles (UCNPs) for cell and tissue analysis requires a comprehensive understanding of their interactions with biological entities to prevent toxicity or harmful effects. Whereas most studies focus on cancer cells, this work addresses non-cancerous cells with their regular in vitro physiology. Since it is generally accepted that surface chemistry largely determines biocompatibility in general and uptake of nanomaterials in particular, two bilayer surface coatings with different surface shielding properties have been studied: (i) a phospholipid bilayer membrane (PLM) and (ii) an amphiphilic polymer (AP).
Department of Biomedical Engineering, Translational Tissue Engineering Center, Johns Hopkins Translational ImmunoEngineering Center, and the Institute for Nanobiotechnology, Johns Hopkins School of Medicine, 400 N. Broadway, Smith Building 5017, Baltimore, Maryland 21231, United States.
Biomimetic particles that can replicate aspects of natural biological cell function are useful for advanced biological engineering applications. Engineering such particles requires mimicking the chemical complexity of the surface of biological cells, and this can be achieved by coating synthetic particles with naturally derived cell membranes. Past research has demonstrated the feasibility of utilizing cell membrane coatings from a variety of cell types to achieve extended blood circulation half-life.
HIV is a lentivirus characterized by the formation of its mature core. Visualization and structural examination of HIV requires purification of virions to high concentrations. The yield and integrity of these virions are crucial for ensuring a uniform representation of all viral particles in subsequent analyses.
