Three functionally redundant plant-specific paralogs are core subunits of the SAGA histone acetyltransferase complex in Arabidopsis

• Published in: Molecular plant 2021-07, Vol.14 (7), p.1071-1087
• Main Authors: Wu, Chan-Juan, Liu, Zhen-Zhen, Wei, Long, Zhou, Jin-Xing, Cai, Xue-Wei, Su, Yin-Na, Li, Lin, Chen, She, He, Xin-Jian
• Format: Article
• Language: English
• Subjects: ADA2B; Arabidopsis - enzymology; Arabidopsis Proteins - chemistry; Arabidopsis Proteins - metabolism; Conserved Sequence; development; HAG1; histone acetylation; Histone Acetyltransferases - metabolism; Humans; Multiprotein Complexes - chemistry; Multiprotein Complexes - genetics; Multiprotein Complexes - metabolism; Plants, Genetically Modified; Protein Subunits - analysis; Protein Subunits - chemistry; Protein Subunits - genetics; Protein Subunits - metabolism; SAGA; SCS1; Species Specificity
• ISSN: 1674-2052; 1752-9867
• DOI: 10.1016/j.molp.2021.03.014

The SAGA (Spt-Ada-Gcn5 acetyltransferase) complex is an evolutionarily conserved histone acetyltransferase complex that has a critical role in histone acetylation, gene expression, and various developmental processes in eukaryotes. However, little is known about the composition and function of the SAGA complex in plants. In this study, we found that the SAGA complex in Arabidopsis thaliana contains not only conserved subunits but also four plant-specific subunits: three functionally redundant paralogs, SCS1, SCS2A, and SCS2B (SCS1/2A/2B), and a TAF-like subunit, TAFL. Mutations in SCS1/2A/2B lead to defective phenotypes similar to those caused by mutations in the genes encoding conserved SAGA subunits HAG1 and ADA2B, including delayed juvenile-to-adult phase transition, late flowering, and increased trichome density. Furthermore, we demonstrated that SCS1/2A/2B are required for the function of the SAGA complex in histone acetylation, thereby promoting the transcription of development-related genes. These results together suggest that SCS1/2A/2B are core subunits of the SAGA complex in Arabidopsis. Compared with SAGA complexes in other eukaryotes, the SAGA complexes in plants have evolved unique features that are necessary for normal growth and development. The SAGA histone acetyltransferase complex contains some conserved subunits, but it remains unclear whether this complex contains any plant-specific subunits. This study comprehensively investigates the composition of the Arabidopsis SAGA complex and characterizes three functionally redundant plant-specific paralogs, SCS1, SCS2A, and SCS2B, as core subunits, thereby revealing a unique feature of the SAGA complex in plants.