FUNCTIONAL ANALYSIS OF ATRX, A HOMOLOGUE OF HISTONE H3.3 CHROMATINREMODELING FACTOR, IN ARABIDOPSIS THALIANA

Abstract

IN MAMMALIANS, REGULATION OF HISTONE H3.3 DISTRIBUTION IS CLOSELY RELATED TO GENE EXPRESSION AND THE UNDERLINE MECHANISMS HAVEN BEEN SHOWN TO HAVE AT LEAST TWO INDEPENDENT HISTONE H3.3 DEPOSITION PATHWAYS MEDIATED BY HISTONE CHAPERONES: 1) THE HIRA DEPENDENT PATHWAY AT TRANSCRIPTION START SITE (TSS) AND GENE BODIES OF TRANSCRIPTIONALLY ACTIVE LOCI; 2) THE ATRX/DAXX DEPENDENT PATHWAY AT PERICENTRIC HETEROCHROMATIN AND TELOMERES. SIMILAR TO MAMMALIANS, IN PLANTS, THE DEPOSITION OF H3.3 VARIANT IS ALSO STRONGLY CORRELATED WITH ACTIVE GENES AT EUCHROMATIN IN A TRANSCRIPTION DEPENDENT MANNER. HOWEVER, THE UNDERLINE MECHANISMS OF HISTONE H3.3 INCORPORATION IN PLANTS ARE STILL UNKNOWN. SINCE HIRA AND ATRX (BUT NOT DAXX) ARE CONSERVED IN PLANTS, HERE, WE APPLIED A REVERSE GENETIC METHOD TO STUDY FUNCTIONS OF THESE TWO HISTONE H3.3 ASSOCIATED PROTEIN CANDIDATES USING A PLANT MODEL SYSTEM, ARABIDOPSIS THALIANA. MY RESULTS, WHICH WERE FOCUSED ON ATRX, SHOW THAT, UNLIKE IN MAMMALIANS, ARABIDOPSIS