Structures and Mechanisms of Protein Remodeling Machines

When a cellular protein has done its job or lost its utility, it should be removed, recycled, or remodeled. These tasks are performed by members of the ubiquitous family of AAA ATPases (ATPases associated with diverse cellular activities) that convert the energy of ATP hydrolysis into mechanical forces that can unfold protein aggregates, degrade unwanted proteins, and remodel protein complexes. Continue reading → Structures and Mechanisms of Protein Remodeling Machines

Mechanisms of Epigenetic Inheritance

A central issue in epigenetics is whether and how epigenetic information in gametes (sperm and egg) is inherited. Cairns and colleagues discovered that “Placeholder” nucleosomes, containing histone variants, occupy DNA regions lacking methylation in both sperm and early embryos. Continue reading → Mechanisms of Epigenetic Inheritance

Identifying RNAs from Invading Viruses

Biochemical and structural studies from Bass, Shen, Iwasa, and colleagues revealed how Dicer-2, an RNA processing, and antiviral defense enzyme, distinguishes and differentially processes double-stranded RNA (dsRNA) substrates by sensing the unique chemistry at their termini. Continue reading → Identifying RNAs from Invading Viruses

Cellular Membrane Remodeling

Cells are continually severing, fusing, and reshaping their membranes. One of the essential cellular membrane remodeling systems is the ESCRT (Endosomal Sorting Complexes Required for Transport) pathway, whose cellular functions include endosomal membrane remodeling, membrane repair, enveloped virus budding, closure of the nuclear envelope, and cytokinetic abscission. Continue reading → Cellular Membrane Remodeling