Molecular mechanism of the deposition of centromeric histone 3

• Main Author: Kim, Shermain
• Other Authors: School of Biological Sciences
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Science::Biological sciences::Molecular biology
• Online Access: http://hdl.handle.net/10356/16359
• Institution: Nanyang Technological University

Eukaryotic chromosomes consist of DNA wrapped around histones, forming nucleosomes. Each nucleosome contains two histone proteins of each of the H2A, H2B, H3 and H4 class. The centromere is a specialized condensed region of chromosome comprising a H3 variant that differs from conventional histones. HTR12 is a centromeric H3 variant. However, the molecular mechanism of HTR12 deposition is largely unknown. The Chromatin Assembly Factor 1 (CAF-1) complex, including members of MSI1, FAS2 and FAS2, plays a role in the canonical H3 deposition. In wild type A. thaliana, HTR12 is absent in the vegetative cell during male gametogenesis. However, the fact that msi1 but not fas1 mutants showed ectopic HTR12 expression in the vegetative cell, suggested that other complexes instead of CAF-1 may be involved in HTR12 deposition. I further investigated the mutants from the MSI/MET1 pathway and excluded the involvement of MET1 in HTR12 deposition. MSI1, FIE, FIS2 and MEA form the Polycomb Group (PcG) complex. I observed that fie and rbr1 mutants also affect HTR12 deposition in a manner similar to msi1 mutants. I postulated that a FIE/MSI1/RBR1 complex might be responsible for HTR12 deposition in the vegetative cell during Arabidopsis male gametogenesis.