The Nucleosomal Surface as a Docking Station for Kaposi's Sarcoma Herpesvirus LANA

122

155

The repair of DNA double-strand breaks (DSBs) requires open, flexible chromatin domains. The NuA4–Tip60 complex creates these flexible chromatin structures by exchanging histone H2A.Z onto nucleosomes and promoting acetylation of histone H4. Here, we demonstrate that the accumulation of H2A.Z on nucleosomes at DSBs is transient, and that rapid eviction of H2A.Z is required for DSB repair. Anp32e, an H2A.Z chaperone that interacts with the C-terminal docking domain of H2A.Z, is rapidly recruited to DSBs. Anp32e functions to remove H2A.Z from nucleosomes, so that H2A.Z levels return to basal within 10 min of DNA damage. Further, H2A.Z removal by Anp32e disrupts inhibitory interactions between the histone H4 tail and the nucleosome surface, facilitating increased acetylation of histone H4 following DNA damage. When H2A.Z removal by Anp32e is blocked, nucleosomes at DSBs retain elevated levels of H2A.Z, and assume a more stable, hypoacetylated conformation. Further, loss of Anp32e leads to increased CtIP-dependent end resection, accumulation of single-stranded DNA, and an increase in repair by the alternative nonhomologous end joining pathway. Exchange of H2A.Z onto the chromatin and subsequent rapid removal by Anp32e are therefore critical for creating open, acetylated nucleosome structures and for controlling end resection by CtIP. Dynamic modulation of H2A.Z exchange and removal by Anp32e reveals the importance of the nucleosome surface and nucleosome dynamics in processing the damaged chromatin template during DSB repair.

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Histone chaperone Anp32e removes H2A.Z from DNA double-strand breaks and promotes nucleosome reorganization and DNA repair

Gürsoy-Yüzügüllü

Ayrapetov

Price

2015

122

155

“…Both N-terminal LANA (N-LANA) and C-terminal LANA (C-LANA) are essential for function. N-LANA associates with mitotic chromosomes via binding histones H2A/H2B, and C-LANA simultaneously binds KSHV terminal repeat (TR) DNA (7,(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). Thus, LANA tethers the viral genome to host chromosomes and distributes viral DNA to daughter nuclei during mitosis.…”

Section: Oss-mentioning

confidence: 99%

Kaposi's sarcoma-associated herpesvirus LANA recruits the DNA polymerase clamp loader to mediate efficient replication and virus persistence

Sun

Tsurimoto

Juillard

et al. 2014

Significance Kaposi's sarcoma herpesvirus (KSHV) latently infects tumor cells, and viral episomal DNA replicates once each cell cycle. KSHV does not express DNA replication proteins during latency. Instead, KSHV latency-associated nuclear antigen (LANA) recruits host cell DNA replication machinery to the replication origin. However, the mechanism by which LANA mediates replication is uncertain. Here, we show LANA recruits replication factor C, the DNA polymerase clamp [proliferating cell nuclear antigen (PCNA)] loader, in a critical step for viral DNA replication. Our findings suggest that PCNA loading is a rate-limiting step in DNA replication that is incompatible with KSHV persistence. LANA-enhanced PCNA loading is necessary for virus replication and persistent infection. These data reveal a therapeutic target for inhibition of KSHV persistence in malignant cells.

“…The H18R substitution was made to potentially strengthen crystal interparticle interactions based on the observation that several proteins bind the acidic patch of the nucleosome core analogously to the H4 tail, but have an arginine side-chain at the position homologous to H 18 (20)(21)(22). In the crystal packing of ASP, the DNA at SHL +2 is bound by an H4 tail (16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26), whereas at the twofold symmetric SHL −2 it is not (6, 23). ASP H4 R 17 H 18 R 19 , localized by the interactions of the adjacent K 20 , V 21, and R 23 side chains with the H2A-H2B acidic patch of the neighboring NCP, binds the backbone of the SHL +2 TC step.…”

Section: Significancementioning

confidence: 99%

X-ray structure of the MMTV-A nucleosome core

Frouws

Duda

Richmond

2016

The conformation of DNA bound in nucleosomes depends on the DNA sequence. Questions such as how nucleosomes are positioned and how they potentially bind sequence-dependent nuclear factors require near-atomic resolution structures of the nucleosome core containing different DNA sequences; despite this, only the DNA for two similar α-satellite sequences and a sequence (601) selected in vitro have been visualized bound in the nucleosome core. Here we report the 2.6-Å resolution X-ray structure of a nucleosome core particle containing the DNA sequence of nucleosome A of the 3′-LTR of the mouse mammary tumor virus (147 bp MMTV-A). To our knowledge, this is the first nucleosome core particle structure containing a promoter sequence and crystallized from Mg 2+ ions. It reveals sequence-dependent DNA conformations not seen previously, including kinking into the DNA major groove.chromatin | nucleosome | DNA | X-ray structure | MMTV D NA in eukaryotic cells is wrapped repeatedly in nucleosomes to form chromatin, the substrate engaged by the nuclear machinery to carry out repair, replication, recombination, and transcription of genomes. Nucleosome mapping in situ combined with biochemical studies has revealed that nucleosome positions determine access to DNA regulatory sequences essential to these processes (1, 2). Nucleosome position is determined chiefly by DNA sequence and ATP-dependent chromatin remodeling factors (3-5). The nucleosome includes a linker DNA of variable length and a nucleosome core containing a histone octamer and 147 bp of DNA (6). Many high-resolution structures of nucleosome cores with differing DNA sequences are required to see how the details of DNA conformation could affect nucleosome positioning and dynamics, as well as nuclear factor binding. The DNA studied would most interestingly represent natural sequences of transcription promoters and enhancer elements.Our knowledge of sequence-dependent structure of DNA bound in the nucleosome core relative to the amount of DNA bound in genomes is extremely limited. A resolution of at least 2.6 Å is necessary to evaluate differences in DNA conformations and assess solvent interactions adequately. To date, this highly reliable "library" of DNA structural information pertinent to the nucleosome core consists primarily of two similar sequences of half α-satellite repeats and half the artificially "evolved" sequence 601 (7-10). Further investigations have been limited to substitution of short sequence elements in one of the α-satellite sequences (11, 12). These high-resolution structures have hinged on using palindromic sequences to avoid twofold averaging imposed by crystal packing. The lack of twofold symmetry in the full 601 sequence, for example, resulted in superposition of the electron density of the two different half-sequences (9).We describe here the X-ray structure of a nucleosome core particle (NCP) containing a DNA sequence from mouse mammary tumor virus (MMTV) determined at 2.6 Å resolution. To our knowledge, this is the first NCP structure conta...