Volume 23 Issue 10, October 2016

A potent toxin present in the venom of a fish-hunting cone snail is a minimized insulin (Con-Ins G1) lacking key residues involved in the receptor binding of most insulins. New data show that Con-Ins G1 nevertheless binds potently to the human insulin receptor, owing to a rearrangement that compensates for the lack of a critical binding residue.

Methicillin resistance in the clinically important bacterium Staphylococcus aureus (MRSA) has evolved in multiple S. aureus lineages through acquisition of chromosomally integrating mobile genetic elements named SCCmec. Now Rice and colleagues show that the conserved SCCmec cch gene encodes an active DNA helicase, thus suggesting that extrachromosomal replication is part of the enigmatic SCCmec horizontal-transfer mechanism.

Cas1–Cas2 integrase achieves full-site integration only for proper targets and protospacers, whereas at non-CRISPR sites, integration stalls at the half-site intermediate, thereby protecting host genome integrity during CRISPR immune adaptation.

A cryo-EM structure of toxin component TcdA1 embedded in lipid nanodiscs reveals details of the mechanism used by this bacterial toxin to insert into the host cell membrane.

One of the conserved proteins of the Staphylococcus aureus mobile genomic island responsible for methicillin resistance is an active MCM-like helicase, thus suggesting replication that would enhance the efficiency of horizontal gene transfer.

Cryo-EM and mass spectrometry analyses of the spike glycoprotein trimer from coronavirus HcoV-NL63 reveal an extensive glycan shield that covers the protein surface, including an epitope targeted by neutralizing antibodies against several coronaviruses.

Crystal structures of HIV Env trimer with native glycosylation in complex with neutralizing antibodies reveal a glycan shield of high-mannose and complex-type N-glycan and indicate a path for germline-targeting vaccine design.

Structural elucidation and biochemical analysis of a cone snail insulin venom that binds and activates the human insulin receptor may permit design of ultrafast-acting insulin analogs for diabetes therapy.

A systematic analysis reveals that acidic or phosphorylated residues upstream of the PDZ-binding motif contribute to efficient recognition of cargos by the SNX27 PDZ domain, thus leading to the identification of hundreds of potential new SNX27 ligands.

The crystal structure of HIV-1 accessory protein Vpr in complex with human UNG2 and DDB1–DCAF1 provides insight into how the viral protein directs UNG2 for degradation.

The structurally constrained knotted configuration of the RNA methyltransferase TrmD captures the free energy of substrate binding to facilitate catalysis.