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AtEAF1 is a potential platform protein for Arabidopsis NuA4 acetyltransferase complex.

Bieluszewski T, Galganski L, Sura W, Bieluszewska A, Abram M, Ludwikow A, Ziolkowski PA, Sadowski J - BMC Plant Biol. (2015)

Bottom Line: Plants carrying a T-DNA insertion in one of the genes encoding AtEAF1 showed decreased FLC expression and early flowering, similarly to Atyaf9 mutants.Chromatin immunoprecipitation analyses of the single mutant Ateaf1b-2 and artificial miRNA knock-down Ateaf1 lines showed decreased levels of H4K5 acetylation in the promoter regions of major flowering regulator genes, further supporting the role of AtEAF1 as a subunit of the plant NuA4 complex.Growing evidence suggests that the molecular functions of the NuA4 and SWR1 complexes are conserved in plants and contribute significantly to plant development and physiology.

View Article: PubMed Central - PubMed

ABSTRACT

Background: Histone acetyltransferase complex NuA4 and histone variant exchanging complex SWR1 are two chromatin modifying complexes which act cooperatively in yeast and share some intriguing structural similarities. Protein subunits of NuA4 and SWR1-C are highly conserved across eukaryotes, but form different multiprotein arrangements. For example, the human TIP60-p400 complex consists of homologues of both yeast NuA4 and SWR1-C subunits, combining subunits necessary for histone acetylation and histone variant exchange. It is currently not known what protein complexes are formed by the plant homologues of NuA4 and SWR1-C subunits.

Results: We report on the identification and molecular characterization of AtEAF1, a new subunit of Arabidopsis NuA4 complex which shows many similarities to the platform protein of the yeast NuA4 complex. AtEAF1 copurifies with Arabidopsis homologues of NuA4 and SWR1-C subunits ARP4 and SWC4 and interacts physically with AtYAF9A and AtYAF9B, homologues of the YAF9 subunit. Plants carrying a T-DNA insertion in one of the genes encoding AtEAF1 showed decreased FLC expression and early flowering, similarly to Atyaf9 mutants. Chromatin immunoprecipitation analyses of the single mutant Ateaf1b-2 and artificial miRNA knock-down Ateaf1 lines showed decreased levels of H4K5 acetylation in the promoter regions of major flowering regulator genes, further supporting the role of AtEAF1 as a subunit of the plant NuA4 complex.

Conclusions: Growing evidence suggests that the molecular functions of the NuA4 and SWR1 complexes are conserved in plants and contribute significantly to plant development and physiology. Our work provides evidence for the existence of a yeast-like EAF1 platform protein in A. thaliana, filling an important gap in the knowledge about the subunit organization of the plant NuA4 complex.

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Mutations inAtEAF1andAtYAF9genes affectFLCexpression and flowering time. (a) Comparison of plants grown under long day conditions (LD). (b) Relative expression levels of FLC transcript compared to WT control. Seedlings were collected in the middle of the light photoperiod. (c) Comparison of flowering time represented by an average number of true rosette leaves at the stage where the flower stem is 1 cm long. (d) Representative rosettes of plants grown under short day conditions (SD) at the stage when the leaves were counted. The bar length is 5 cm. In all graphs, asterisks indicate statistical significance of the difference between each mutant and the WT control. A single asterisk indicates a p-value < 0.05, double asterisk – p-value < 0.01 (t-test).
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Fig3: Mutations inAtEAF1andAtYAF9genes affectFLCexpression and flowering time. (a) Comparison of plants grown under long day conditions (LD). (b) Relative expression levels of FLC transcript compared to WT control. Seedlings were collected in the middle of the light photoperiod. (c) Comparison of flowering time represented by an average number of true rosette leaves at the stage where the flower stem is 1 cm long. (d) Representative rosettes of plants grown under short day conditions (SD) at the stage when the leaves were counted. The bar length is 5 cm. In all graphs, asterisks indicate statistical significance of the difference between each mutant and the WT control. A single asterisk indicates a p-value < 0.05, double asterisk – p-value < 0.01 (t-test).

Mentions: AtYAF9A-deficient plants express FLC at reduced levels [16]. Physical interaction between AtYAF9A and AtEAF1, and their similarity to functional counterparts in yeast, YAF9 and EAF1, respectively, suggested that AtEAF1 might also influence FLC transcription. To test this prediction we used plants with a T-DNA insertion near the 5′ end of the last exon of the AtEAF1B gene (Figure 3a, Additional file 4). We will refer to this line as Ateaf1b-2. Compared to wild-type seedlings, Ateaf1b-2 mutants expressed FLC at significantly reduced levels under both long day (LD) and short day (SD) conditions (Figure 3b).Figure 3


AtEAF1 is a potential platform protein for Arabidopsis NuA4 acetyltransferase complex.

Bieluszewski T, Galganski L, Sura W, Bieluszewska A, Abram M, Ludwikow A, Ziolkowski PA, Sadowski J - BMC Plant Biol. (2015)

Mutations inAtEAF1andAtYAF9genes affectFLCexpression and flowering time. (a) Comparison of plants grown under long day conditions (LD). (b) Relative expression levels of FLC transcript compared to WT control. Seedlings were collected in the middle of the light photoperiod. (c) Comparison of flowering time represented by an average number of true rosette leaves at the stage where the flower stem is 1 cm long. (d) Representative rosettes of plants grown under short day conditions (SD) at the stage when the leaves were counted. The bar length is 5 cm. In all graphs, asterisks indicate statistical significance of the difference between each mutant and the WT control. A single asterisk indicates a p-value < 0.05, double asterisk – p-value < 0.01 (t-test).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4358907&req=5

Fig3: Mutations inAtEAF1andAtYAF9genes affectFLCexpression and flowering time. (a) Comparison of plants grown under long day conditions (LD). (b) Relative expression levels of FLC transcript compared to WT control. Seedlings were collected in the middle of the light photoperiod. (c) Comparison of flowering time represented by an average number of true rosette leaves at the stage where the flower stem is 1 cm long. (d) Representative rosettes of plants grown under short day conditions (SD) at the stage when the leaves were counted. The bar length is 5 cm. In all graphs, asterisks indicate statistical significance of the difference between each mutant and the WT control. A single asterisk indicates a p-value < 0.05, double asterisk – p-value < 0.01 (t-test).
Mentions: AtYAF9A-deficient plants express FLC at reduced levels [16]. Physical interaction between AtYAF9A and AtEAF1, and their similarity to functional counterparts in yeast, YAF9 and EAF1, respectively, suggested that AtEAF1 might also influence FLC transcription. To test this prediction we used plants with a T-DNA insertion near the 5′ end of the last exon of the AtEAF1B gene (Figure 3a, Additional file 4). We will refer to this line as Ateaf1b-2. Compared to wild-type seedlings, Ateaf1b-2 mutants expressed FLC at significantly reduced levels under both long day (LD) and short day (SD) conditions (Figure 3b).Figure 3

Bottom Line: Plants carrying a T-DNA insertion in one of the genes encoding AtEAF1 showed decreased FLC expression and early flowering, similarly to Atyaf9 mutants.Chromatin immunoprecipitation analyses of the single mutant Ateaf1b-2 and artificial miRNA knock-down Ateaf1 lines showed decreased levels of H4K5 acetylation in the promoter regions of major flowering regulator genes, further supporting the role of AtEAF1 as a subunit of the plant NuA4 complex.Growing evidence suggests that the molecular functions of the NuA4 and SWR1 complexes are conserved in plants and contribute significantly to plant development and physiology.

View Article: PubMed Central - PubMed

ABSTRACT

Background: Histone acetyltransferase complex NuA4 and histone variant exchanging complex SWR1 are two chromatin modifying complexes which act cooperatively in yeast and share some intriguing structural similarities. Protein subunits of NuA4 and SWR1-C are highly conserved across eukaryotes, but form different multiprotein arrangements. For example, the human TIP60-p400 complex consists of homologues of both yeast NuA4 and SWR1-C subunits, combining subunits necessary for histone acetylation and histone variant exchange. It is currently not known what protein complexes are formed by the plant homologues of NuA4 and SWR1-C subunits.

Results: We report on the identification and molecular characterization of AtEAF1, a new subunit of Arabidopsis NuA4 complex which shows many similarities to the platform protein of the yeast NuA4 complex. AtEAF1 copurifies with Arabidopsis homologues of NuA4 and SWR1-C subunits ARP4 and SWC4 and interacts physically with AtYAF9A and AtYAF9B, homologues of the YAF9 subunit. Plants carrying a T-DNA insertion in one of the genes encoding AtEAF1 showed decreased FLC expression and early flowering, similarly to Atyaf9 mutants. Chromatin immunoprecipitation analyses of the single mutant Ateaf1b-2 and artificial miRNA knock-down Ateaf1 lines showed decreased levels of H4K5 acetylation in the promoter regions of major flowering regulator genes, further supporting the role of AtEAF1 as a subunit of the plant NuA4 complex.

Conclusions: Growing evidence suggests that the molecular functions of the NuA4 and SWR1 complexes are conserved in plants and contribute significantly to plant development and physiology. Our work provides evidence for the existence of a yeast-like EAF1 platform protein in A. thaliana, filling an important gap in the knowledge about the subunit organization of the plant NuA4 complex.

Show MeSH