Identification of a replication-independent replacement histone H3 in the basidiomycete Ustilago maydis.

ABSTRACT: Ustilago maydis is a haploid basidiomycete with single genes for two distinct histone H3 variants. The solitary U1 gene codes for H3.1, predicted to be a replication-independent replacement histone. The U2 gene is paired with histone H4 and produces a putative replication-coupled H3.2 variant. These predictions were evaluated experimentally. U2 was confirmed to be highly expressed in the S phase and had reduced expression in hydroxyurea, and H3.2 protein was not incorporated into transcribed chromatin of stationary phase cells. Constitutive expression of U1 during growth produced ~25% of H3 as H3.1 protein, more highly acetylated than H3.2. The level of H3.1 increased when cell proliferation slowed, a hallmark of replacement histones. Half of new H3.1 incorporated into highly acetylated ch

SUBMITTER: Anju V 

PROVIDER: S-EPMC3138321 | biostudies-literature | 2011 Jul

REPOSITORIES: biostudies-literature