Inheritance of chromatin marks during cell replication in plants University of Warwick in United Kingdom

The correct development of multicellular organisms entails the specifications of distinct cell types. Each of these cellular identities must be conserved during later cell divisions. At the same time, genomic integrity must be preserved in every cell and every cell cycle during the genome replication cycles that occur during the developmental differentiation. The replication of the genome requires that not only the genetic material, DNA, but also the chromatin, a macromolecular entity formed by the association of DNA with histone proteins into nucleosomes, is correctly duplicated. Therefore, both DNA and histone proteins, together with their post-translational modifications (PTMs), must be properly transferred to the daughter chromatin fibres. Since the chromatin landscape is a key component of gene regulation, the transferring process of parental histones and their association with new histone proteins is crucial to maintaining the memory of transcriptional programs of parental chromatin in the daughter chromatin after cell division. It is well established that DNA methylation is copied from the parental DNA strand to the progeny strand immediately after DNA replication and involves the cooperative interactions between DNA methylation and histone modifications.

Recent work has provided clues on how the transferring of chromatin information is mechanistically linked to the DNA replication machinery. The precise molecular mechanisms that underpin the transfer of chromatin information into the newly synthesised genome are not yet fully understood. Our knowledge in plants has been limited, in part because most studies are based on the analysis of mutants in key regulators of chromatin structure and in factors implicated in the deposition or removal of histone PTMs, which usually accumulate pleiotropic genetic and epigenetic abnormalities. Surprisingly, the precise machinery implicated in the transfer of chromatin information and how it is localised at specific genome regions during DNA replication remains currently unknown.

Objectives

The plan of work is divided into three main objectives:

(1) Define the role that histone demethylases play in balancing the inheritance of chromatin marks during replication. The student will use a new system to engineer conditional knockouts of different components of the chromatin machinery to assess their role in the inheritance of different chromatin marks.

(2) Identify the molecular components contributing to the correct transfer of chromatin information in plants. To this aim, the student will perform a targeted proteomic analysis using cell cultures to identify the factors implicated in the replication of histone marks.

(3) To use super-resolution microscopy analysis to monitor the dynamic changes in chromatin during different stages of the cell cycle and their association with components of the replisome, a macromolecular complex responsible for replicating the genomic DNA.

Collectively, this work will further our understanding of how different chromatin states are inherited in plants.

Primary Supervisor: Professor Jose Gutierrez-Marcos

Secondary Supervisor: Professor Daniel Hebenstreit

University of Registration: University of Warwick

BBSRC Research Themes:

• Sustainable Agriculture and Food ( Plant and Crop Science )
• Understanding the Rules of Life ( Plant Science , Systems Biology )