A Human RNA Polymerase II Complex Containing Factors That Modify Chromatin Structure

ABSTRACT

We have isolated a human RNA polymerase II complex that contains chromatin structure remodeling activity and histone acetyltransferase activity. This complex contains the Srb proteins, the Swi-Snf complex, and the histone acetyltransferases CBP and PCAF in addition to RNA polymerase II. Notably, the general transcription factors are absent from this complex. The complex was purified by two different methods: conventional chromatography and affinity chromatography using antibodies directed against CDK8, the human homolog of the yeast Srb10 protein. Protein interaction studies demonstrate a direct interaction between RNA polymerase II and the histone acetyltransferases p300 and PCAF. Importantly, p300 interacts specifically with the nonphosphorylated, initiation-competent form of RNA polymerase II. In contrast, PCAF interacts with the elongation-competent, phosphorylated form of RNA polymerase II.

ACKNOWLEDGMENTS

We thank Edio Maldonado for thoughtful comments and advice during early steps of the work. We also thank G. LeRoy for purifying the Swi-Snf complex, W. Wang and G. Crabtree for human Swi-Snf subunit antibodies, M. Montminy for the CBP antibodies, J. Hurwitz for the RNA antibodies, R. Young for the hSRB7 antibodies, and members of the Reinberg laboratory for helpful suggestions. We also thank Mike Hampsey for helpful comments on the manuscript.

This work was supported by a grant from the National Institutes of Health (GM-37120) and from the Howard Hughes Medical Institute to D.R.

ADDENDUM

Results similar to those reported here were reported by Neish et al. (49a) following submission of the manuscript.