ZINC-FINGER PROTEINS

Considerable progress has been made over the past year concerning the structures of various classes of zinc-finger proteins and the mechanisms by which they recognize particular nucleic acid targets. Both NMR and X-ray structures have become available for the DNA-binding domain of the yeast protein GAL4. These have revealed the detailed architecture of the Zn2(Cys)6 binuclear cluster and the accompanying structure that binds DNA. Indirect studies have yielded models for the structure of the TFIIIA-5S RNA gene complex. In addition, more detailed data has become available concerning the roles of the invariant metal-binding and hydrophobic residues in stabilizing the zinc-finger structure. Structural information concerning the TFIIIA-like zinc fingers has guided experiments that are leading to potentially useful rules relating to DNA binding site preference. The role of zinc in the biological function of retroviral nucleocapsid proteins has also become clearer.