Jingjun hong
China USTC
Published in 2021
- Structural and biochemical insights into the recognition of RNA helicase CGH-1 by CAR-1 in C. elegans
- Authors: Yong Zhang, Mengqi Lv, Fudong Li, Meili Li, Jiahai Zhang, Yunyu Shi, Jingjun Hong
- Journal: Biochem Biophys Res Commun
- Description:
- A protein-RNA complex containing the RNA helicase CGH-1 and a germline specific RNA-binding protein CAR-1 is involved in various aspects of function in C. elegans. However, the structural basis for the assembly of this protein complex remains unclear. Here, we elucidate the molecular basis of the recognition of CGH-1 by CAR-1. Additionally, we found that the ATPase activity of CGH-1 is stimulated by NTL-1a MIF4G domain in vitro. Furthermore, we determined the structures of the two RecA-like domains of CGH-1 by X-ray crystallography at resolutions of 1.85 and 2.40 Å, respectively. Structural and biochemical approaches revealed a bipartite interface between CGH-1 RecA2 and the FDF-TFG motif of CAR-1. NMR and structure-based mutations in CGH-1 RecA2 or CAR-1 attenuated or disrupted CGH-1 binding to CAR-1, assessed by ITC and GST-pulldown in vitro. These findings provide insights into a conserved mechanism in the recognition of CGH-1 by CAR-1. Together, our data provide the missing physical links in understanding the assembly and function of CGH-1 and CAR-1 in C. elegans.
Published in 2019
- Dynamic acetylation of the kinetochore-associated protein HEC1 ensures accurate microtubule-kinetochore attachment
- Authors: Gangyin Zhao, Yubao Cheng, Ping Gui, Meiying Cui, Wei Liu, Wenwen Wang, Xueying Wang, Mahboob Ali, Zhen Dou, Liwen Niu, Haiyan Liu, Leonard Anderson, Ke Ruan, Jingjun Hong, Xuebiao Yao
- Journal: J Biol Chem
- Description:
- Faithful chromosome segregation during mitosis is critical for maintaining genome integrity in cell progeny and relies on accurate and robust kinetochore-microtubule attachments. The NDC80 complex, a tetramer comprising kinetochore protein HEC1 (HEC1), NDC80 kinetochore complex component NUF2 (NUF2), NDC80 kinetochore complex component SPC24 (SPC24), and SPC25, plays a critical role in kinetochore-microtubule attachment. Mounting evidence indicates that phosphorylation of HEC1 is important for regulating the binding of the NDC80 complex to microtubules. However, it remains unclear whether other post-translational modifications, such as acetylation, regulate NDC80-microtubule attachment during mitosis. Here, using pulldown assays with HeLa cell lysates and site-directed mutagenesis, we show that HEC1 is a bona fide substrate of the lysine acetyltransferase Tat-interacting protein, 60 kDa (TIP60) and that TIP60-mediated acetylation of HEC1 is essential for accurate chromosome segregation in mitosis. We demonstrate that TIP60 regulates the dynamic interactions between NDC80 and spindle microtubules during mitosis and observed that TIP60 acetylates HEC1 at two evolutionarily conserved residues, Lys-53 and Lys-59. Importantly, this acetylation weakened the phosphorylation of the N-terminal HEC1(1-80) region at Ser-55 and Ser-62, which is governed by Aurora B and regulates NDC80-microtubule dynamics, indicating functional cross-talk between these two post-translation modifications of HEC1. Moreover, the TIP60-mediated acetylation was specifically reversed by sirtuin 1 (SIRT1). Taken together, our results define a conserved signaling hierarchy, involving HEC1, TIP60, Aurora B, and SIRT1, that integrates dynamic HEC1 acetylation and phosphorylation for accurate kinetochore-microtubule attachment in the maintenance of genomic stability during mitosis.
Published in 2019
- Structure of the primed state of the ATPase domain of chromatin remodeling factor ISWI bound to the nucleosome
- Authors: Sagar Chittori, Jingjun Hong, Yawen Bai, Sriram Subramaniam
- Journal: Nucleic Acids Res
- Description:
- ATP-dependent chromatin remodeling factors of SWI/SNF2 family including ISWI, SNF2, CHD1 and INO80 subfamilies share a conserved but functionally non-interchangeable ATPase domain. Here we report cryo-electron microscopy (cryo-EM) structures of the nucleosome bound to an ISWI fragment with deletion of the AutoN and HSS regions in nucleotide-free conditions and the free nucleosome at ∼ 4 Å resolution. In the bound conformation, the ATPase domain interacts with the super helical location 2 (SHL 2) of the nucleosomal DNA, with the N-terminal tail of H4 and with the α1 helix of H3. Density for other regions of ISWI is not observed, presumably due to disorder. Comparison with the structure of the free nucleosome reveals that although the histone core remains largely unchanged, remodeler binding causes perturbations in the nucleosomal DNA resulting in a bulge near the SHL2 site. Overall, the structure of the nucleotide-free ISWI-nucleosome complex is similar to the corresponding regions of the recently reported ADP bound ISWI-nucleosome structures, which are significantly different from that observed for the ADP-BeFx bound structure. Our findings are relevant to the initial step of ISWI binding to the nucleosome and provide additional insights into the nucleosome remodeling process driven by ISWI.
Published in 2018
- Structural mechanisms of centromeric nucleosome recognition by the kinetochore protein CENP-N
- Authors: Sagar Chittori, Jingjun Hong, Hayden Saunders, Hanqiao Feng, Rodolfo Ghirlando, Alexander E Kelly, Yawen Bai, Sriram Subramaniam
- Journal: Science
- Description:
- Accurate chromosome segregation requires the proper assembly of kinetochore proteins. A key step in this process is the recognition of the histone H3 variant CENP-A in the centromeric nucleosome by the kinetochore protein CENP-N. We report cryo-electron microscopy (cryo-EM), biophysical, biochemical, and cell biological studies of the interaction between the CENP-A nucleosome and CENP-N. We show that human CENP-N confers binding specificity through interactions with the L1 loop of CENP-A, stabilized by electrostatic interactions with the nucleosomal DNA. Mutational analyses demonstrate analogous interactions in Xenopus, which are further supported by residue-swapping experiments involving the L1 loop of CENP-A. Our results are consistent with the coevolution of CENP-N and CENP-A and establish the structural basis for recognition of the CENP-A nucleosome to enable kinetochore assembly and centromeric chromatin organization.
Published in 2014
- The catalytic subunit of the SWR1 remodeler is a histone chaperone for the H2A.Z-H2B dimer
- Authors: Jingjun Hong, Hanqiao Feng, Feng Wang, Anand Ranjan, Jianhong Chen, Jiansheng Jiang, Rodolfo Ghirlando, T Sam Xiao, Carl Wu, Yawen Bai
- Journal: Molecular Cell
- Description:
- Histone variant H2A.Z-containing nucleosomes exist at most eukaryotic promoters and play important roles in gene transcription and genome stability. The multisubunit nucleosome-remodeling enzyme complex SWR1, conserved from yeast to mammals, catalyzes the ATP-dependent replacement of histone H2A in canonical nucleosomes with H2A.Z. How SWR1 catalyzes the replacement reaction is largely unknown. Here, we determined the crystal structure of the N-terminal region (599-627) of the catalytic subunit Swr1, termed Swr1-Z domain, in complex with the H2A.Z-H2B dimer at 1.78 Å resolution. The Swr1-Z domain forms a 310 helix and an irregular chain. A conserved LxxLF motif in the Swr1-Z 310 helix specifically recognizes the αC helix of H2A.Z. Our results show that the Swr1-Z domain can deliver the H2A.Z-H2B dimer to the DNA-(H3-H4)2 tetrasome to form the nucleosome by a histone chaperone mechanism.
Published in 2013
- Identification of functionally conserved regions in the structure of the chaperone/CenH3/H4 complex
- Authors: Jingjun Hong, Hanqiao Feng, Zheng Zhou, Rodolfo Ghirlando, Yawen Bai
- Journal: J Mol Biol
- Description:
- In eukaryotes, a variant of conventional histone H3 termed CenH3 epigenetically marks the centromere. The conserved CenH3 chaperone specifically recognizes CenH3 and is required for CenH3 deposition at the centromere. Recently, the structures of the chaperone/CenH3/H4 complexes have been determined for Homo sapiens (Hs) and the budding yeasts Saccharomyces cerevisiae (Sc) and Kluyveromyces lactis (Kl). Surprisingly, the three structures are very different, leading to different proposed structural bases for chaperone function. The question of which structural region of CenH3 provides the specificity determinant for the chaperone recognition is not fully answered. Here, we investigated these issues using solution NMR and site-directed mutagenesis. We discovered that, in contrast to previous findings, the structures of the Kl and Sc chaperone/CenH3/H4 complexes are actually very similar. This new finding reveals that both budding yeast and human chaperones use a similar structural region to block DNA from binding to the histones. Our mutational analyses further indicate that the N-terminal region of the CenH3 α2 helix is sufficient for specific recognition by the chaperone for both budding yeast and human. Thus, our studies have identified conserved structural bases of how the chaperones recognize CenH3 and perform the chaperone function.