Publications by authors named "Laura Burbaum"
Sarcomeres, the basic contractile units of striated muscle, produce the forces driving muscular contraction through cross-bridge interactions between actin-containing thin filaments and myosin II-based thick filaments. Until now, direct visualization of the molecular architecture underlying sarcomere contractility has remained elusive. Here, we use in situ cryo-electron tomography to unveil sarcomere contraction in frozen-hydrated neonatal rat cardiomyocytes.
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- The development of minimal cell division machineries in synthetic biology focuses on controlling large structures like Giant Unilamellar Vesicles (GUVs) using active elements much larger than molecular structures.
- The study employs advanced methods to encapsulate and analyze bundled actin filaments in GUVs, revealing key parameters that allow actin polymerization to mimic various cellular networks.
- Findings indicate that effective membrane binding is essential for forming stable actin rings, which contract and deform the vesicles when activated by myosin motors, while cortex-like actin networks can stabilize these deformations.
Structural impact of K63 ubiquitin on yeast translocating ribosomes under oxidative stress.
Proc Natl Acad Sci U S A
September 2020
Article Synopsis
- Subpopulations of ribosomes fine-tune protein synthesis in response to oxidative stress, with K63 ubiquitination emerging as a key posttranslational modification affecting ribosome function.
- Using cryoelectron microscopy, researchers identified 3D structures of K63 ubiquitinated ribosomes from stressed yeast, revealing their unique presence in a polysome arrangement at a specific stage of translation elongation.
- The study shows that K63 ubiquitin causes structural changes that destabilize important ribosomal proteins, ultimately inhibiting the function of eEF2 and regulating translation during oxidative stress.
In mammalian cells, secretory and membrane proteins are translocated across or inserted into the endoplasmic reticulum (ER) membrane by the universally conserved protein-conducting channel Sec61, which has been structurally studied in isolated, detergent-solubilized states. Here we structurally and functionally characterize native, non-solubilized ribosome-Sec61 complexes on rough ER vesicles using cryo-electron tomography and ribosome profiling. Surprisingly, the 9-Å resolution subtomogram average reveals Sec61 in a laterally open conformation, even though the channel is not in the process of inserting membrane proteins into the lipid bilayer.
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