In eukaryotes, transcription of protein-encoding genes is stronglyregulated by posttranslational modifications of histones that affectthe accessibility of the DNA by RNA polymerase II (RNAPII). TheElongator complex was originally identified in yeast as a histoneacetyltransferase (HAT) complex that activates RNAPII-mediatedtranscription. In Arabidopsis thaliana, the Elongator mutants elo1,elo2, and elo3 with decreased leaf and primary root growth due toreduced cell proliferation identified homologs of components ofthe yeast Elongator complex, Elp4, Elp1, and Elp3, respectively.Here we show that the Elongator complex was purified from plantcell cultures as a six-component complex. The role of plant Elongatorin transcription elongation was supported by colocalization ofthe HAT enzyme, ELO3, with euchromatin and the phosphorylatedform of RNAPII, and reduced histone H3 lysine 14 acetylation at thecoding region of the SHORT HYPOCOTYL 2 auxin repressor and theLAX2 auxin influx carrier gene with reduced expression levels in theelo3 mutant. Additional auxin-related genes were down-regulatedin the transcriptome of elo mutants but not targeted by the ElongatorHAT activity showing specificity in target gene selection. Biologicalrelevance was apparent by auxin-related phenotypes andmarker gene analysis. Ethylene and jasmonic acid signaling andabiotic stress responses were up-regulated in the elo transcriptomeand might contribute to the pleiotropic elo phenotype. Thus,although the structure of Elongator and its substrate are conserved,target gene selection has diverged, showing that auxin signalingand influx are under chromatin control.
Plant Elongator regulates auxin-related genes during RNA polymerase II transcription elongation
Bruno L.;Bitonti M. B.;
2010-01-01
Abstract
In eukaryotes, transcription of protein-encoding genes is stronglyregulated by posttranslational modifications of histones that affectthe accessibility of the DNA by RNA polymerase II (RNAPII). TheElongator complex was originally identified in yeast as a histoneacetyltransferase (HAT) complex that activates RNAPII-mediatedtranscription. In Arabidopsis thaliana, the Elongator mutants elo1,elo2, and elo3 with decreased leaf and primary root growth due toreduced cell proliferation identified homologs of components ofthe yeast Elongator complex, Elp4, Elp1, and Elp3, respectively.Here we show that the Elongator complex was purified from plantcell cultures as a six-component complex. The role of plant Elongatorin transcription elongation was supported by colocalization ofthe HAT enzyme, ELO3, with euchromatin and the phosphorylatedform of RNAPII, and reduced histone H3 lysine 14 acetylation at thecoding region of the SHORT HYPOCOTYL 2 auxin repressor and theLAX2 auxin influx carrier gene with reduced expression levels in theelo3 mutant. Additional auxin-related genes were down-regulatedin the transcriptome of elo mutants but not targeted by the ElongatorHAT activity showing specificity in target gene selection. Biologicalrelevance was apparent by auxin-related phenotypes andmarker gene analysis. Ethylene and jasmonic acid signaling andabiotic stress responses were up-regulated in the elo transcriptomeand might contribute to the pleiotropic elo phenotype. Thus,although the structure of Elongator and its substrate are conserved,target gene selection has diverged, showing that auxin signalingand influx are under chromatin control.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
