Promoter-specific targeting of human SWI-SNF complex by Epstein-Barr virusnuclear protein 2

The multiprotein human SWI-SNF (hSWI-SNF) complex is a chromatin-remodeling machine that facilitates transcription by overcoming chromatin-mediated ge ne repression. We had previously shown that hSNF5/INl1, an intrinsic, consi stent component of the hSWI/SNF complex, is associated with Epstein-Barr nu clear antigen 2 (EBNA2) and have proposed that EBNA2 directs this complex t o key EBNA2-responsive viral and cellular genes. Using chromatin immunoprec ipitation and quantitative PCR, we show that antibodies directed against co mponents of the hSWI-SNF complex preferentially precipitate chromatin-assoc iated DNA that contains a targeted EBNA2-responsive element in the context of both episomal and cellular chromatin. This enrichment does not occur in EBNA2-negative cells or when the EBNA2-responsive element is mutated. The s table association of the hSWI-SNF complex with the EBNA2-responsive promote r can also be disrupted by deletion of the TATA element, suggesting that EB NA2 in itself is insufficient to mediate stable targeting of the hSWI-SNF c omplex. These results demonstrate that recruitment of the hSWI-SNF complex to selected promoters can occur in vivo through its interaction with site-s pecific activator proteins and that stable targeting may require the presen ce of basal transcription factors.