In Science this week, a multi-institute team of European researchers report on a new technique to study protein folding and unfolding. Called high-speed force spectroscopy, the method was used to unfold and observe the muscle protein tinin, which scientists had previously been unable to visualize fast enough in order to compare the process to high-speed computer simulations. With their method, however, the investigators were able to watch tinin unfolding at approximately four millimeters per second — the lower limit of most simulations.
Also in Science, a group led by University of Massachusetts Medical School investigators provides new insights into the organization of the mitotic chromosome. Noting that the internal organization of these chromosomes has been largely unknown, the scientists applied chromosome conformation-capture methods — 5C and Hi-C — across the cell cycle and revealed two alternative three-dimensional folding states of the human genome. They found that the "highly compartmentalized and cell-type-specific organization" described previously for non-synchronous cells is restricted to interphase. "In metaphase, we identify a homogenous folding state, which is locus-independent, common to all chromosomes, and consistent among cell types, suggesting a general principle of metaphase chromosome organization," the investigators add.