The Journal of Microscopy would like to thank all those referees who reviewed papers for the Journal during 2011. Your assistance and contribution to the Journal is greatly appreciated.

Protein/ice interactions are investigated by a novel method based on measuring the characteristic features of X-ray diffraction (XRD) patterns of hexagonal ice (Ih). Aqueous solutions of four proteins and other solutes are studied using high-resolution synchrotron XRD. Two pharmaceutical proteins, recombinant human albumin and monoclonal antibody (both at 100 mg/mL), have a pronounced effect on the properties of ice crystals, reducing the size of the Ih crystalline domains and increasing the microstrain. Lysozyme (100 mg/ mL) and an antifreeze protein (1 mg/mL) have much weaker impact on Ih. Neither of the proteins studied exhibit preferred interactions with specific crystalline faces of Ih. It is proposed that the pharmaceutical proteins interact with ice crystals indirectly by accumulating in the quasi-liquid layer next to ice crystallization front, rather than directly, via a sorption on ice crystals. This is the first report, to the best of our knowledge, of major difference in the protein/ice interaction between non-antifreeze proteins. Another important finding is a detection of a second (minor) population of ice crystals, which is tentatively identified as a high-pressure form of ice, possibly IceIII or IceIX. This finding highlights a potential role of mechanical stresses in freeze-induced destabilization of proteins.

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Electron cryotomography analysis of Dam1C/DASH at the kinetochore–spindle interface in situ

Deng

Chen

et al. 2018

Journal of Cell Biology

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In dividing cells, depolymerizing spindle microtubules move chromosomes by pulling at their kinetochores. While kinetochore subcomplexes have been studied extensively in vitro, little is known about their in vivo structure and interactions with microtubules or their response to spindle damage. Here we combine electron cryotomography of serial cryosections with genetic and pharmacological perturbation to study the yeast chromosome segregation machinery in vivo. Each kinetochore microtubule has one (rarely, two) Dam1C/DASH outer kinetochore assemblies. Dam1C/DASH contacts the microtubule walls and does so with its flexible “bridges”; there are no contacts with the protofilaments’ curved tips. In metaphase, ∼40% of the Dam1C/DASH assemblies are complete rings; the rest are partial rings. Ring completeness and binding position along the microtubule are sensitive to kinetochore attachment and tension, respectively. Our study and those of others support a model in which each kinetochore must undergo cycles of conformational change to couple microtubule depolymerization to chromosome movement.

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The Journal of Microscopy would like to thank all those referees who reviewed papers for the Journal during 2011. Your assistance and contribution to the Journal is greatly appreciated.

Cited by 8 publications

References 38 publications

Cryogenic Preparations of Biological Specimens for Cryo-Electron Tomography

Cryogenic Preparations of Biological Specimens for Cryo-Electron Tomography

Protein/Ice Interaction: High-Resolution Synchrotron X-ray Diffraction Differentiates Pharmaceutical Proteins from Lysozyme

Electron cryotomography analysis of Dam1C/DASH at the kinetochore–spindle interface in situ

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