"Histone Acetylation and Chromatin Remodeling are Required for UV-B Dependent Transcriptional Activation of Regulated Genes in Maize”

PAULA CASATI; CAMPI M.; CHU F.; SUZUKI N.; MALTBY D.; ALMA L. BURLINGAME; VIRGINIA WALBOT

The Plant Cell

Año: 2008 vol. 20 p. 827 - 842

1040-4651

The nuclear proteomes of maize (Zea mays) lines that differ in UV-B tolerance were compared by two-dimensional gelelectrophoresis after UV light treatment. Differential accumulation of chromatin proteins, particularly histones, constitutedthe largest class identified by mass spectrometry. UV-B–tolerant landraces and the B73 inbred line show twice as manyprotein changes as the UV-B–sensitive b, pl W23 inbred line and transgenic maize expressing RNA interference constructsdirected against chromatin factors. Mass spectrometic analysis of posttranslational modifications on histone proteinsdemonstrates that UV-B–tolerant lines exhibit greater acetylation on N-terminal tails of histones H3 and H4 after irradiation.These acetylated histones are enriched in the promoter and transcribed regions of the two UV-B–upregulated genesexamined; radiation-sensitive lines lack this enrichment. DNase I and micrococcal nuclease hypersensitivity assays indicatethat chromatin adopts looser structures around the selected genes in the UV-B–tolerant samples. Chromatin immunoprecipitationexperiments identified additional chromatin factor changes associated with the nfc102 test gene after UV-Btreatment in radiation-tolerant lines. Chromatin remodeling is thus shown to be a key process in acclimation to UV-B, andlines deficient in this process are more sensitive to UV-B.