The elongata mutants identify a functional Elongator complex in plants with a role in cell proliferation during organ growth

The key enzyme for transcription of protein-encoding genes ineukaryotes is RNA polymerase II (RNAPII). The recruitment of thisenzyme during transcription initiation and its passage along thetemplate during transcription elongation is regulated through theassociation and dissociation of several complexes. Elongator is ahistone acetyl transferase complex, consisting of six subunits(ELP1–ELP6), that copurifies with the elongating RNAPII in yeastand humans. We demonstrate that point mutations in three Arabidopsisthaliana genes, encoding homologs of the yeast Elongatorsubunits ELP1, ELP3 (histone acetyl transferase), and ELP4 areresponsible for the phenotypes of the elongata2 (elo2), elo3, andelo1 mutants, respectively. The elo mutants are characterized bynarrow leaves and reduced root growth that results from a decreasedcell division rate. Morphological and molecular phenotypesshow that the ELONGATA (ELO) genes function in the samebiological process and the epistatic interactions between the ELOgenes can be explained by the model of complex formation inyeast. Furthermore, the plant Elongator complex is geneticallypositioned in the process of RNAPII-mediated transcription downstreamof Mediator. Our data indicate that the Elongator complexis evolutionarily conserved in structure and function but revealthat the mechanism by which it stimulates cell proliferation isdifferent in yeast and plants