The cover picture shows that the radical sam enzyme hpnh catalyzes the coupling of an extremely hydrophilic substrate s‐adenosylmethionine (sam) and an extremely hydrophobic substrate hopene, producing adenosylhopane as a key intermediate in bacteriohopanepolyol biosynthesis. Coupling of the two substrates with totally distinct properties is somewhat analogous to the “1 up, 1 down” buddy system in freediving, in which one diver dives down and the other stays above the surface. Meeting the buddy in the middle way in the late stage of diving is always the most gratifying moment for the divers. More details are discussed by zhang et al. on page 39—42.
