Abscisic acid (ABA) is involved in the plant stress responses via the PYL/PYR receptors. Yan and colleagues now present the crystal structures of PYL proteins alone, with ABA and in a ternary complex with a target phosphatase, providing insight into ABA sensing and signaling. The winter scene on the cover, by Richard Mann, depicts plant environmental stress. pp 1230–1236

The crystal structure of a mammalian sialyltransferase, presented by Strynadka and colleagues, provides a structural basis for understanding the mechanism and specificity of this important class of enzymes. The sugar modification is represented by candy (by Mike Cook, www.mike-cook.net). pp 1186–1188

New data from Towers, James and colleagues on the Rhesus macaque protein TRIMCyp suggest remodeling of a host protein to protect against a specific pathogen, in this instance HIV-2. Such changes give insights into the evolutionary battle between host and pathogen, represented as a chess board on the cover (by V. Kolobanov from istockphoto.com). pp 1036-1042

By comparing exon-intron position in higher eukaryotes to available large scale nucleosome positioning datasets, two independent groups now find that exons tend to have higher nucleosome occupancy than introns. Artwork by Erin Boyle in the style of Joan Miró, suggested by Luisa Lente. pp 990–995 and pp 996–1001, News and Views p 902

Map and related bacterial effectors can regulate host cytoskeletal dynamics. New data reveal that Map is a potent GEF for the GTPase Cdc42 and suggest how these effectors can distinguish between host targets. Cover image from iStockphoto (www.istockphoto.com). pp 853–860

The human Hedgehog-interacting protein (HHIP) binds and inhibits vertebrate hedgehog (Hh) signaling molecules. Structures of HHIP in complex with vertebrate Hh are presented. The cover image represents the propeller domain of HHIP as an apple. (by Chepko Danil from iStockphoto) pp 691-697 and pp 698-703

"Conduit," original artwork from Colleen Buzzard (http://www.colleenbuzzard.com), expresses how the information in a linear sequence or code (the Braille on the paper) is conveyed into a three-dimensional structure through folding. This issue contains a special Focus on Protein Folding. pp 573-612

Rosen and colleagues examine the reconstituted human and fly WAVE regulatory complex, which transmits information from the Rac GTPase to the actin cytoskeleton, revealing common regulatory principles for the WASP family. Cover photograph by plainview from istockphoto.com. pp 561– 563

Ribosomal proteins make assembly more cooperative by discriminating against non-native conformations of the E. coli 16S rRNA. Ramaswamy and Woodson use hydroxyl radical footprinting to reveal a conformational switch during assembly of the 30S 5' domain. Cover art by Priya Ramaswamy is an interpretation of a footprinting gel. pp 438–445

Photosystem II (PSII) catalyzes the first light-dependent step in photosynthesis. An improved structural model of cyanobacterial PSII reveals a complex system of channels for the access and transport of substrates and products, illustrated by the image of a hedge maze. Photo by Andrew Green for iStockphoto. pp 334-342

Fatty acid synthase is composed of several catalytic domains that work in sequence. Asturias and colleagues use single-particle EM analysis of rat FAS to reveal the movements of the domains during the reaction cycle. The cover image of a flamenco dancer represents the complex motions of FAS in action (© Emanuele Ferrari, iStockphoto). pp 190-197

The myosin motor domain contains multiple clefts and binding pockets for nucleotide and allosteric effectors. Fedorov et al. identify a previously uncharacterized binding pocket used by pentabromopseudilin to allosterically inhibit myosin activity. Cover by Rita R. Manstein. Acrylic paint on canvas. pp 80-88