Welcome to BioCAT

BioCAT is now able to carry out research on any subject, not just COVID-19 related projects. However, COVID-19 related projects will still be given priority on the beamline. Additionally, due to an Argonne-wide policy, no users are allowed on site and we can run fewer experiments than usual. If you are interested in beam time please contact us.

Science Highlights

Tarantula myosin interacting-heads motif explains tetanic and post-tetanic phosphorylation mechanisms

Striated muscle contraction involves sliding of actin thin filaments along myosin thick filaments, controlled by calcium through thin filament activation. In relaxed muscle, the two heads of myosin interact with each other on the filament surface to form the interacting-heads motif (IHM). A key question is how both heads are released from the surface to approach actin and produce force. We used time-resolved synchrotron X-ray diffraction to study tarantula muscle before and after tetani. The patterns showed that the IHM is present in live relaxed muscle. Tetanic contraction produced only a very small backbone elongation, implying that mechanosensing - proposed in vertebrate muscle - is not of primary importance in tarantula. Rather, thick filament activation results from increases in myosin phosphorylation that release a fraction of heads to produce force, with the remainder staying in the ordered IHM configuration.

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Compound nebulin mutations cause changes in thin filament structure.

Nebulin is a giant protein that winds around the actin filaments in the sarcomeres of skeletal muscle. Mutations in the nebulin gene (NEB) cause typical nemaline myopathy (NM), a muscle disorder characterized by muscle weakness that are difficult to treat. The authors of this study created a mouse model that mimics the typical nebulin-based NM patient with compound-heterozygous mutations. X-ray diffraction studies on the BioCAT beamline 18ID provided a structural explanation for the muscle weakness. This new Compound-Het mouse model will be useful for testing experimental therapies for typical NM.

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How Prion-like domains Drive Liquid-Liquid Phase Transitions in Cells

Liquid-liquid phase separation (LLPS) provides a way for cells to create membraneless micro-environments (“condensates”) that have been proposed to be involved in diverse cellular processes including stress responses, RNA splicing, mitosis, chromatin organization, and the clustering of receptors at membranes. Proteins driving LLPS often contain intrinsically disordered prion like domains (PLD’s) that appear to be necessary and sufficient to produce LLPS. In a recent paper in the journal Science, researchers used a combination of NMR, multiscale simulations and Size Exclusion Chromatography SAXS experiments at BioCAT to discover sequence features that determine the phase behavior of PLD’s.

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News

Everything BioSAXS 6 workshop wrapup

BioCAT held its sixth intensive HOW-TO course in BioSAXS from 10/26/20-10/29/20 with 24 remote participants. There wwere four days of lectures and hands-on software tutorials on the basics of BioSAXS data collection and processing from expert practitioners in the field. Participants could elect to mail in samples for data collection prior to the course, and roughly half of them sent research samples and were able to analyze their own data as part of the workshop.

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SAXS studies of RNA elements from the SARS-CoV-2 virus at BioCAT

As part of the global effort to study the SARS-CoV-2 virus causing the COVID-19 pandemic, BioCAT is carrying out SEC-MALS-SAXS studies of RNA elements from the virus.

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Everything BioSAXS 6 workshop announced

BioCAT is offering the all-virtual Everything BioSAXS 6 workshop October 26-29th. Participants will receive four days of virtual lectures and hands-on software tutorials on the basics of BioSAXS data collection and processing. They will also be able to mail samples to BioCAT for data collection prior to the workshop. Registration is now closed, but you can still get on the waitlist.

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