#SINGLECRYSTAL SOFTWARE DM3 FILE SERIAL#
#SINGLECRYSTAL SOFTWARE DM3 FILE SERIES#

Finally, X-ray tomography 15 or scattering of intense X-ray pulses from free-electron lasers 16 is unlikely to reveal the structure of large, complex, aperiodic objects such as whole cells or organelles at molecular resolution in the foreseeable future.

Atomic force microscopy 14 can in principle deliver molecular or even atomic resolution, but only at the surface of objects on an atomically flat, solid support.

#SINGLECRYSTAL SOFTWARE DM3 FILE SERIAL#

Transmission electron microscopy of serial sections 12 or block-face imaging by scanning electron microscopy 13 of plastic-embedded biological samples provide low-resolution views of cellular volumes but likewise do not reveal molecular detail. Super-resolution light microscopy 10, 11 is superb at revealing the position or distances between light-emitting labels attached to proteins of interest with a precision of tens of nm, but it does not reveal the structure of the protein itself, even at low resolution. Other methods to study the 3D structure of cells or organelles do not provide molecular detail. Cryo-ET is particularly suitable for studying large complexes in biological membranes, because the membranes appear with good contrast and are easy to trace in 3D tomographic volumes. Cryo-ET is currently the only method that delivers accurate three-dimensional (3D) volumes of cells, cellular compartments or organelles at molecular resolution. The technique we have used to determine this arrangement is electron cryo-tomography (cryo-ET). This arrangement has important implications for the mechanisms of mitochondrial energy conversion. Subsequent studies from our group and others 7 have confirmed that the ATP synthase is arranged in long rows of dimers along the tightly curved ridges of the inner mitochondrial membrane cristae 8, while the proton pumps of the electron transport chain appear to be located at either side of the rows 9. The distribution of the ATP synthase in the inner mitochondrial membrane has been widely assumed to be random, but an early finding 5 and our own initial results 6 indicated that this is not the case. Although high-resolution structures of most of the mitochondrial ATP synthase components 1-3 and low-resolution maps of the whole complex 4 are available, it is important to establish the structure and conformation of the working enzyme in the membrane. In order to understand the mechanisms behind mitochondrial energy conversion, we need to determine the structure of the ATP synthase in situ, and to find out how it is arranged and distributed in the inner mitochondrial membrane. By converting an electrochemical proton gradient across the inner mitochondrial membrane into chemical bond energy, the mitochondrial ATP synthase produces most of the ATP that drives cellular processes. Mitochondria are the power-houses of the cell. By subtomogram averaging we obtained a structure of the mitochondrial ATP synthase dimer within the cristae membrane. We find that ATP synthases are organized in rows of dimers along highly curved apices of the inner membrane cristae, whereas complex I is randomly distributed in the membrane regions on either side of the rows. Here we show how we use electron cryo-tomography to study the in situ organization of large membrane protein complexes in mitochondria. A fit of available high-resolution structures to the 3D volume then produces atomic models of protein complexes in their native environment. In this way, 3D maps with a resolution of 2 nm or better can be obtained. Recognizable, recurring features are enhanced by subtomogram averaging, by which individual subvolumes are cut out, aligned and averaged to reduce noise. The signal-to-noise ratio of the tomographic volume is inherently low.

#SINGLECRYSTAL SOFTWARE DM3 FILE SERIES#

In the electron microscope, tilt series are recorded at liquid nitrogen temperature, from which 3D tomograms are reconstructed. To achieve this, the aqueous sample is rapidly vitrified in liquid ethane, which preserves it in a close-to-native, frozen-hydrated state. Electron cryo-tomography is a powerful tool in structural biology, capable of visualizing the three-dimensional structure of biological samples, such as cells, organelles, membrane vesicles, or viruses at molecular detail.

Singlecrystal software dm3 file