CH 3 CO + , 55). The numbers show m/z values, and the key fragments and their relative intensities are indicated in parentheses.

The crystal structure of the cyclin D-dependent kinase Cdk6 bound to the p19 INK4d protein has been determined at 1.9 A resolution. The results provide the first structural information for a cyclin D-dependent protein kinase and show how the INK4 family of CDK inhibitors bind. The structure indicates that the conformational changes induced by p19INK4d inhibit both productive binding of ATP and the cyclin-induced rearrangement of the kinase from an inactive to an active conformation. The structure also shows how binding of an INK4 inhibitor would prevent binding of p27Kip1, resulting in its redistribution to other CDKs. Identification of the critical residues involved in the interaction explains how mutations in Cdk4 and p16INK4a result in loss of kinase inhibition and cancer.

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Currently there are relatively few antiviral therapeutics, and most which do exist are highly pathogen-specific or have other disadvantages. We have developed a new broad-spectrum antiviral approach, dubbed Double-stranded RNA (dsRNA) Activated Caspase Oligomerizer (DRACO) that selectively induces apoptosis in cells containing viral dsRNA, rapidly killing infected cells without harming uninfected cells. We have created DRACOs and shown that they are nontoxic in 11 mammalian cell types and effective against 15 different viruses, including dengue flavivirus, Amapari and Tacaribe arenaviruses, Guama bunyavirus, and H1N1 influenza. We have also demonstrated that DRACOs can rescue mice challenged with H1N1 influenza. DRACOs have the potential to be effective therapeutics or prophylactics for numerous clinical and priority viruses, due to the broad-spectrum sensitivity of the dsRNA detection domain, the potent activity of the apoptosis induction domain, and the novel direct linkage between the two which viruses have never encountered.