The genetic material of virtually all eukaryotes exists as chromatin. The basic unit of chromatin is a nucleosome, an octameric complex of histones H2A, H2B, H3 and H4, around which about 150 base pairs of DNA are wrapped. Chromatin is a complex and highly dynamic environment. Nucleosomes are differentiated by variants of histones H2A and H3 and by many histone post-translational modifications, chromatin-associated proteins and linker histones. Nucleosomes are positioned both by the underlying DNA sequence and by remodeling enzymes and histone chaperones that can mobilize, disassemble or replace histone subunits. In most eukaryotes, chromatin is also modified by methylation of cytosine bases in DNA.
Our goal is to understand how chromatin components interrelate and integrate to regulate transcriptional activity. We combine genetics and biochemistry with genomics and computational analysis to study DNA methylation, deposition of histone variants, chromatin associated proteins and nucleosome remodeling. Our primary model organism is Arabidopsis, which has a compact, gene-rich genome with extensive DNA methylation and numerous viable mutants in key chromatin-related proteins. These features provide an exciting opportunity to analyze chromatin on a genome-wide scale.