Date:10 April 2024 (Wednesday)
Time: 5:00 pm – 6:00 pm
Venue: Cheung Kung Hai Lecture Theatre 1, G/F, William M.W. Mong Block, 21 Sassoon Road

5:00 p.m.

Presenter: Jiho LEE (MPhil candidate)
Primary Supervisor: Dr. Xiucong BAO
Presentation Title: Deep investigation of C1QBP's histone chaperoning activity
Abstract: Histone chaperones play key roles in maintaining genome and epigenome integrity. Recently, we identified complement C1q binding protein (C1QBP), a ubiquitous acidic glycoprotein, as a histone chaperone to mediate tetrasome assembly, yet the exact mechanism is understudied. Here, we report that both the c-terminal region of histone H3 and H4 interact with C1QBP. Mechanistically, we demonstrated that acidic regions of C1QBP are binding hot-spot for recognition of histone proteins. We also demonstrated that different modifications occurring on histone tails can cause distinctive recognition. In future, we will investigate how C1QBP modulates chromatin dynamics in living cells. We anticipate our analysis to be a starting point for more sophisticated in vitro and in vivo studies on histone chaperone C1QBP.

5:30 p.m.

Presenter: Ruixun LU (PhD candidate)
Primary Supervisor: Prof. Chengmin QIAN
Presentation Title: Structural and mechanistic studies of DNMT1 in the maintenance of DNA methylation
Abstract: Maintenance of genomic methylation patterns during DNA replication is primarily mediated by DNA methyltransferase 1 (DNMT1). DNMT1 is a self-inhibitory enzyme. The catalytic pocket of DNMT1 is occupied by its RFTS domain, which prevents substrate DNAs accessing to the catalytic pocket. A number of structures of DNMT1 in complex with the individual DNA segment or post-translationally modified histone tail have been determined to understand the molecular mechanism for DNMT1 activation in the maintenance of DNA methylation. However, the complete working mechanism of DNMT1 during replication remains to be fully explored. In this study, we reconstituted the modified nucleosome with both dual mono-ubiquitinated histone H3 (H3Ub2) and trimethylated histone H4 (H4K20Cme3), which could form a stable complex with DNMT1 in vitro, and we aim to explore the underlying mechanism of DNMT1 in maintaining DNA methylation during DNA replication through cryo-EM structure analysis.

ALL ARE WELCOME

Should you have any enquiries, please feel free to contact Jerry Siu at 3917 6912.