High-resolution cryo-EM using a common LaB 120-keV electron microscope equipped with a sub-200-keV direct electron detector.

High-resolution cryo-electron microscopy (cryo-EM) requires costly 200- to 300-keV cryo-transmission electron microscopes (cryo-TEMs) with field emission gun (FEG) sources, stable columns, constant-powered lenses, autoloader, and direct electron detectors (DED). Recent advances in 100-keV imaging with the emergence of sub-200-keV optimized DED technology promises the development of more affordable cryo-TEMs. So far, 100-keV imaging has required microscopes with FEG sources.

Structural plasticity of the coiled-coil interactions in human SFPQ.

The proteins SFPQ (splicing Factor Proline/Glutamine rich) and NONO (non-POU domain-containing octamer-binding protein) are mammalian members of the Drosophila Behaviour/Human Splicing (DBHS) protein family, which share 76% sequence identity in their conserved 320 amino acid DBHS domain. SFPQ and NONO are involved in all steps of post-transcriptional regulation and are primarily located in mammalian paraspeckles: liquid phase-separated, ribonucleoprotein sub-nuclear bodies templated by NEAT1 long non-coding RNA. A combination of structured and low-complexity regions provide polyvalent interaction interfaces that facilitate homo- and heterodimerisation, polymerisation, interactions with oligonucleotides, mRNA, long non-coding RNA, and liquid phase-separation, all of which have been implicated in cellular homeostasis and neurological diseases including neuroblastoma.

Membrane mechanics dictate axonal pearls-on-a-string morphology and function.

Axons are ultrathin membrane cables that are specialized for the conduction of action potentials. Although their diameter is variable along their length, how their morphology is determined is unclear. Here, we demonstrate that unmyelinated axons of the mouse central nervous system have nonsynaptic, nanoscopic varicosities ~200 nm in diameter repeatedly along their length interspersed with a thin cable ~60 nm in diameter like pearls-on-a-string.

Mechanisms of axoneme and centriole elimination in Naegleria gruberi.

The early branching eukaryote Naegleria gruberi can transform transiently from an amoeboid life form lacking centrioles and flagella to a flagellate life form where these elements are present, followed by reversion to the amoeboid state. The mechanisms imparting elimination of axonemes and centrioles during this reversion process are not known. Here, we uncover that flagella primarily fold onto the cell surface and fuse within milliseconds with the plasma membrane.

Convergent evolution of viral-like Borg archaeal extrachromosomal elements and giant eukaryotic viruses.

Unlabelled: Borgs are huge extrachromosomal elements of anaerobic methane-oxidizing archaea. They exist in exceedingly complex microbiomes, lack cultivated hosts and have few protein functional annotations, precluding their classification as plasmids, viruses or other. Here, we used structure prediction methods to investigate potential roles for ∼10,000 Borg proteins.