- Atlastin crossover energizes ER fusion
The GTPase atlastin mediates homotypic membrane ER fusion through trans-dimerization between GTPase heads. Winsor et al. use a mutagenesis approach to show that, upon contact between atlastin heads, the proteins concurrently display GTP hydrolysis-catalyzed head-to-head dimerization and a crossover conformational shift, and these changes energize fusion.
- Regulation of chromosome segregation in oocytes
During mitosis, cells monitor kinetochore–microtubule attachments as a means of detecting errors. Although end-on attachments have not been observed in Caenorhabditis elegans oocytes, Davis-Roca et al. now report that these cells alter key aspects of anaphase progression in the presence of meiotic defects, revealing a new strategy for error detection during cell division.
- Regulating mitotic fidelity in the brain
Mutations in centrosomal and spindle checkpoint proteins cause microcephaly in mammals. Poulton et al. explore their roles in the Drosophila brain. Although loss of either alone is tolerated, combined loss leads to massive mitotic errors, increased cell death, and dramatic perturbations of brain development.
- Chlamydia prevents mitochondrial fragmentation
Chlamydiae are intracellular pathogens that depend on the host for their survival and development. Chowdhury et al. demonstrate that Chlamydia trachomatis infection can prevent mitochondrial fission in primary cells by reducing DRP1 abundance via miR-30c–dependent inhibition of p53.
- New fluorescent sphingomyelin analogs
The behavior of sphingomyelin (SM) in the plasma membrane is unclear. Using new fluorescent SM analogs and single-molecule tracking, Kinoshita et al. find that SM transiently and continually interacts with the glycosylphosphatidylinositol (GPI)-anchored protein CD59 in oligomer size–, cholesterol-, and GPI anchoring–dependent manners.
- Role of PLEKHM1 in vesicle–lysosome fusion
Rab7 and Arl8b mediate vesicle transport and fusion with lysosomes. Marwaha et al. show that the Rab7 effector PLEKHM1 competes with PLEKHM2/SKIP for binding to Arl8b and that Arl8 mediates recruitment of the HOPS complex to PLEKHM1-positive vesicles for fusion, suggesting that Arl8b and its effectors orchestrate lysosomal transport and fusion.
- Membrane remodeling in embryonic abscission
König et al. perform time-resolved electron tomographic reconstructions to decipher the membrane remodeling events in abscission, the final step of cytokinesis, in Caenorhabditis elegans and find that completion of the scission process requires actomyosin-driven membrane remodeling, but not the ESCRT machinery.