Molecular architecture, structure-function relationship, and importance of the Elp3 subunit for the RNA binding of holo-elongator.

The molecular architecture of six-subunit yeast holo-Elongator complex was investigated by the use of immunoprecipitation, two-hybrid interaction mapping, and in vitro studies of binary interactions between individual subunits. Surprisingly, Elp2 is dispensable for the integrity of the holo-Elongator complex, and a purified five-subunit elp2 Delta Elongator complex retains histone acetyltransferase activity in vitro. These results indicate that the WD40 repeats in Elp2 are required neither for subunit-subunit interactions within Elongator nor for Elongator interaction with histones during catalysis. Elp2 and Elp4 were largely dispensable for the association of Elongator with nascent RNA transcript in vivo. In contrast, Elongator-RNA interaction requires the Elp3 protein. Together, these data shed light on the structure-function relationship of the Elongator complex.