Unveiling novel interactions of histone chaperone Asf1 linked to TREX-2 factors Sus1 and Thp1.
Anti-silencing function 1 (Asf1) is a conserved key eukaryotic histone H3/H4 chaperone that participates in a variety of DNA and chromatin-related processes. These include the assembly and disassembly of histones H3 and H4 from chromatin during replication, transcription, and DNA repair. In addition, Asf1 is required for H3K56 acetylation activity dependent on histone acetyltransferase Rtt109. Thus, Asf1 impacts on many aspects of DNA metabolism. To gain insights into the functional links of Asf1 with other cellular machineries, we employed mass spectrometry coupled to tandem affinity purification (TAP) to investigate novel physical interactions of Asf1. Under different TAP-MS analysis conditions, we describe a new repertoire of Asf1 physical interactions and novel Asf1 post-translational modifications as ubiquitination, methylation and acetylation that open up new ways to regulate Asf1 functions. Asf1 co-purifies with several subunits of the TREX-2, SAGA complexes, and with nucleoporins Nup2, Nup60, and Nup57, which are all involved in transcription coupled to mRNA export in eukaryotes. Reciprocally, Thp1 and Sus1 interact with Asf1. Albeit mRNA export and GAL1 transcription are not affected in asf1Δ a strong genetic interaction exists between ASF1 and SUS1. Notably, supporting a functional link between Asf1 and TREX-2, both Sus1 and Thp1 affect the levels of Asf1-dependent histone H3K56 acetylation and histone H3 and H4 incorporation onto chromatin. Additionally, we provide evidence for a role of Asf1 in histone H2B ubiquitination. This work proposes a functional link between Asf1 and TREX-2 components in histone metabolism at the vicinity of the nuclear pore complex.
['Pamblanco|Mercè|M|', 'Oliete-Calvo|Paula|P|', 'García-Oliver|Encar|E|', 'Luz Valero|M|M|', 'Sanchez del Pino|Manuel M|MM|', 'Rodríguez-Navarro|Susana|S|']
D000107:Acetylation D018797:Cell Cycle Proteins D015966:Gene Expression Regulation, Fungal D056488:Histone Chaperones D006657:Histones D008745:Methylation D018832:Molecular Chaperones D009687:Nuclear Proteins D011499:Protein Processing, Post-Translational D034443:RNA Transport D012333:RNA, Messenger D016601:RNA-Binding Proteins D012261:Ribonucleoproteins D012441:Saccharomyces cerevisiae D029701:Saccharomyces cerevisiae Proteins D014158:Transcription, Genetic
histones TREX-2 Sus1 SAGA (5-10) yAsf1 TAP-MS strategy yeast