Learn More
The mechanical properties of F-actin are very significant, given the central structural role played by actin filaments within muscle and the cytoskeleton. We have determined that actin can exist in a state that has a fourfold increase in flexibility over normal F-actin, and nucleotide. Three-dimensional reconstructions from electron micrographs suggest that(More)
The RAD51 protein functions in the processes of DNA repair and in mitotic and meiotic genetic recombination in the yeast Saccharomyces cerevisiae. The protein has adenosine triphosphate-dependent DNA binding activities similar to those of the Escherichia coli RecA protein, and the two proteins have 30 percent sequence homology. RAD51 polymerized on(More)
Image analysis of isolated F-actin filaments shows that the actin helix can be described by a constant rise per subunit but a considerably variable and randomized twist (number of units per turn). The ability of actin subunits to rotate through angles of the order of 10 degrees from their helically ideal positions helps to explain actin's capacity to form(More)
BAR superfamily domains shape membranes through poorly understood mechanisms. We solved structures of F-BAR modules bound to flat and curved bilayers using electron (cryo)microscopy. We show that membrane tubules form when F-BARs polymerize into helical coats that are held together by lateral and tip-to-tip interactions. On gel-state membranes or after(More)
Type IV pili (T4P) are long, thin, flexible filaments on bacteria that undergo assembly-disassembly from inner membrane pilin subunits and exhibit astonishing multifunctionality. Neisseria gonorrhoeae (gonococcal or GC) T4P are prototypic virulence factors and immune targets for increasingly antibiotic-resistant human pathogens, yet detailed structures are(More)
Inflammasomes elicit host defense inside cells by activating caspase-1 for cytokine maturation and cell death. AIM2 and NLRP3 are representative sensor proteins in two major families of inflammasomes. The adaptor protein ASC bridges the sensor proteins and caspase-1 to form ternary inflammasome complexes, achieved through pyrin domain (PYD) interactions(More)
Great progress has been made in advancing an atomic-level model for F-actin. A growing body of data shows, however, that any picture of F-actin must take into account allosteric interactions within subunits, long-range cooperative effects that occur between subunits, and the fact that several conformations of the filament can exist.
Utrophin, like its homologue dystrophin, forms a link between the actin cytoskeleton and the extracellular matrix. We have used a new method of image analysis to reconstruct actin filaments decorated with the actin-binding domain of utrophin, which contains two calponin homology domains. We find two different modes of binding, with either one or two(More)
Many actin-binding proteins contain calponin homology (CH) domains, but the manner in which these domains interact with F-actin has been controversial. Crystal structures have shown the tandem CH domains of alpha-actinin to be in a compact, closed conformation, but the interpretations of complexes of such tandem CH domains with F-actin have been ambiguous.(More)
P olymers of actin (F-actin) form an integral part of the structural framework that supports the plasma membrane of our cells while providing a platform for signaling and metabolic proteins. Most subunits in an actin filament hydrolyze a single molecule of ATP to ADP over the F-actin's lifetime. This hydrolysis is the critical timekeeper of F-actin(More)