SAGA Structures Provide Mechanistic Models for Gene Activation.

Two recent reports by Cramer and Ben-Shem and colleagues present high-resolution structures of the yeast SAGA transcription coactivator complex. These are the first to resolve the stoichiometry and structure of the core. The core contains an octamer-like fold, flexibly links the enzymatic modules, and facilitates TBP loading onto TATA promoters.

Nonreplicative functions of the origin recognition complex.

Origin recognition complex (ORC), a heteromeric six-subunit complex, is the central component of the eukaryotic pre-replication complex. Recent data from yeast, frogs, flies and mammals present compelling evidence that ORC and its individual subunits have nonreplicative functions as well. The majority of these functions, such as heterochromatin formation, chromosome condensation, and segregation are dependent on ORC-DNA interactions.