Gene-specific Transcriptional Activation Mediated by the p150 Subunit of the Chromatin Assembly Factor 1

Abstract

Chromatin assembly factor 1 contains three subunits, p150, p60, and p48. It is essential for coupling nucleosome assembly to newly synthesized DNA. Whether chromatin assembly factor 1 subunits have functions beyond escorting histones, which depends on the complex formation of p150 and p60, has been an issue of great interest. This study reveals a novel role of p150, but not p60, in gene-specific transcriptional activation. We found that p150 transcriptionally activated an essential viral promoter, the major immediate early promoter (MIEP) of the human cytomegalovirus, independently of p60. Knocking down p150 decreased the MIEP function in both transfected and virally infected cells. The chromatin immunoprecipitation analysis and the in vitro protein-DNA binding assay demonstrated that p150 used its KER domain to associate with the MIEP from ؊593 to ؊574 bp. The N-terminal 244 residues were also found essential for p150-mediated MIEP activation, likely through recruiting the acetyltransferase p300 to acetylate local histones. Domain swapping experiments further showed that the KER and the N terminus of p150 acted as an independent DNA binding and transcriptional activation domain, respectively. Because p60 did not seem involved in the reaction, together these results indicate for the first time that p150 directly activates transcription, independently of its histone deposition function.

Host-viral effects of chromatin assembly factor 1 interaction with HCMV IE2

“…We show that (I) HCMV infection upregulates the protein levels of p150 and p60 of CAF1, as well as PCNA and (II) HCMV IE2 binds to p150 and through this interaction locates the CAF1 complex, possibly with histones, to centers of viral genome synthesis to promote HCMV DNA replication. In addition, we unexpectedly found p150, independently of p60, binds to and activates the HCMV major immediate-early promoter that drives IE2 synthesis [54]. Based on all these, it is hypothesized that an IE2-CAF1 autoregulation loop might facilitate HCMV viral DNA replication.…”

Monoallelic expression and epigenetic inheritance sustained by a Trypanosoma brucei variant surface glycoprotein exclusion complex

“…Mammalian CAF-1 sustains somatic cell types 38 and epigenetic memory by interacting with heterochromatin protein 1α, a histone H3 methyltransferase and KRAB-ZFP-associated protein 1; this complex is also associated with sub-nuclear foci 39 . Human CAF-1 can also activate transcription independent of its histone deposition function 40 and the conserved CAF-1 subunit-associated dREAM complex plays a role in specifying and maintaining olfactory receptor gene expression in Drosophila 41 . Thus, in addition to housekeeping roles in chromatin assembly, several lines of evidence suggest an evolutionary conserved role for CAF-1 in sustaining site-specific molecular memories of epigenetic states.…”

How to control an infectious bead string: nucleosome‐based regulation and targeting of herpesvirus chromatin

“…RNAi experiments also demonstrated that several H3‐H4‐specific histone chaperones behave as positive acting factors of the herpesvirus productive cycle: HIRA (which presumably mediates H3.3 incorporation into parental HSV‐1 chromosomes; see previous text) and ASF1B facilitate HSV‐1 lytic replication , whereas chromatin assembly factor 1 (CAF1) promotes HCMV replication by assisting in viral IE gene activation . On the other hand, the H2A‐H2B‐specific histone chaperones template‐activating factor I (TAF‐I) and nucleophosmin 1 (NPM1) seem to negatively regulate HSV‐1 productive infection or KSHV reactivation from latency , respectively (Table ).…”