The cover depicts structures of dynamic and native conformational exchanger (DANCER) proteins, which were computationally designed to switch between predicted conformational states. DANCERs are based on the global fold of streptococcal protein Gβ1 and contain an engineered Trp43 residue that spontaneously exchanges between sequestered and solvent-exposed states on the millisecond timescale. Cover design by Erin Dewalt, based on an image from Adam Damry. Article, p1280

The cover depicts the structures of the RNA aptamers Spinach (green), Mango (orange) and Corn (yellow), which contain G-quadruplexes. Corn provides increased photostability and a red-shifted spectrum that enables imaging of RNA polymerase III transcription, and the structure of Corn reveals an unexpected homodimer. Cover design by Erin Dewalt, based on an image generated by Ethan Tyler. Articles, p1187 and p1195; News & Views, p1140

The decomposition of plant biomass, notably by fungi, relies on a complex set of chemical and enzymatic reactions in which the enzymes known today as lytic polysaccharide monooxygenases (LPMOs) play a key role. The cover depicts a tree trunk from Yellowstone National Park (USA) undergoing fungus-mediated decay. Cover design by Erin Dewalt, based on a photograph provided by Bastien Bissaro. Article, p1123

The cover depicts numerous extracellular membrane vesicles associated with a long cellular process on a neural stem cell, imaged by a scanning electron microscope. Isolated extracellular vesicles were found to be metabolically active, and metabolomics analysis revealed the presence of asparaginase activity attributed to the enzyme asparaginase-like 1. Cover design by Erin Dewalt, based on an image generated by Jose Manuel Garcia-Verdugo and Clara Alfaro-Cervello. Article, p951; News & Views, p924

The cover depicts conidiophores of the fungus Aspergillus nidulans carrying a fungal artificial chromosome (FAC), imaged by a scanning electron microscope and colored artificially. Filamentous fungi are prolific producers of secondary metabolites, and the combination of FAC technology with metabolomic scoring enables the high-throughput linkage of these metabolites with their biosynthetic gene clusters. Cover design by Erin Dewalt, based on an image from Eric W. Roth. Article, p895

Membrane curvature induces sorting of G-protein-coupled receptors within membrane protrusions, potentially as a result of a thermodynamic drive to match receptor shape and elasticity to membrane structure. The image shows fluorescently labeled neuropeptide Y Y2 receptors concentrating at filopodia of surface-adhered neuron-like PC12 cells. Cover design by Erin Dewalt, based on an image generated by Kadla Rosholm. Article, p724

The development of model organisms such as zebrafish and worms progresses from a single cell to the formation of defined tissues and organs. A collection of Commentary, Perspective and Review articles in this issue describe new advances in exploiting the intersection between developmental processes and chemical biology. The cover image depicts the fate mapping of cellular lineages using different fluorescent dyes in a zebrafish embryo (top, colored in red), a Caenorhabditis elegans embryo (middle, colored in brown) and a mouse embryo (bottom, colored in green) at four distinct stages. The stem cells isolated from the mouse blastocyst are cultured and differentiated into neurons. Cover art by Erin Dewalt.

The cover depicts the sponge Dysidea granulosa, which harbors cyanobacterial endosymbionts responsible for the widespread biosynthesis of polybrominated diphenyl ethers (PBDEs) in the marine environment. Naturally produced PBDEs, which are structurally similar to toxic man-made brominated flame retardants, can make up over ten percent of the sponge's weight. Cover design by Erin Dewalt, based on an image from Jason Biggs. Article, p537

Fatty acid synthase (FAS) is a multidomain enzyme complex that can be engineered to generate non-native fatty acids and ketones. The cover depicts the structure of yeast FAS in cross-section, with a miniature factory inside its reaction chamber to represent the production and export of these molecules. Cover design by Erin Dewalt, from imagery provided by Zhiwei Zhu and Martin Grininger. Brief Communications, p360 and p363; News and Views, p344

Producing artificial spider silk with the same tensile strength and elasticity as native silk has historically been difficult. The cover shows new, stronger artificial spider silk produced using an extremely soluble chimeric spider silk protein and a biomimetic spinning method that mimics the narrow duct and acidity changes met by the natural silk protein in the spider glands. Cover design by Erin Dewalt, based on an image created by Lena Holm. Brief Communication, p262

Peptides based on sequences of glycine receptors that interact with gephyrin have been developed that have enhanced affinity and specificity toward blocking gephyrin interactions with these postsynaptic inhibitory receptors. These super-binding peptides are useful for isolating and localizing native gephyrin and for modulating glycinergic synaptic transmission (depicted as stars in a synaptic space of a glass-like neurotransmitter-releasing neuron and a postsynaptic target cell). Cover design by Erin Dewalt, based on an image created by Henning Dalhoff. Article, p153

The cover depicts an acidic patch of ubiquitin (purple) on a chromatin fiber (gray structure) displayed on a background showing cross-peaks from hydrogen-deuterium exchange nuclear magnetic resonance analysis. The image is based on PDB 1UBQ and EMD 2600 visualized with the program Chimera. Cover design by Erin Dewalt, based on an image created by Galia Debelouchina. Article, p105