FRIGIDA and related proteins have a conserved central domain and family specific N- and C- terminal regions that are functionally important

• Published in: Plant molecular biology Vol. 73; no. 4-5; pp. 493 - 505
• Main Authors: Risk, Joanna M, Laurie, Rebecca E, Macknight, Richard C, Day, Catherine L
• Format: Journal Article
• Language: English
• Published: Dordrecht Dordrecht : Springer Netherlands 01.07.2010; Springer Netherlands; Springer Nature B.V
• Subjects: Amino Acid Sequence; Arabidopsis; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins - chemistry; Arabidopsis Proteins - isolation & purification; Arabidopsis Proteins - metabolism; Biochemistry; Biology; Biomedical and Life Sciences; Circular Dichroism; Conserved Sequence; FLC; flowering; Flowers & plants; FRIGIDA; FRIGIDA-LIKE 1; Gene Expression Profiling; Gene Expression Regulation, Plant; Life Sciences; Molecular Sequence Data; Multigene Family - genetics; Plant biology; Plant Pathology; Plant Sciences; Plants, Genetically Modified; Protein Stability; Protein Structure, Tertiary; Proteins; Solubility; Structure-Activity Relationship; Transformation, Genetic; vernalization; Winter; Flowering; FRIGIDA; Vernalization; FRIGIDA-LIKE 1
• ISSN: 0167-4412; 1573-5028
• DOI: 10.1007/s11103-010-9635-2

Arabidopsis accessions are either winter-annuals, which require cold winter temperatures for spring flowering, or rapid-cycling summer annuals. Typically, winter annual accessions have functional FRIGIDA (FRI) and FRIGIDA-LIKE 1 (FRL1) proteins that promote high expression of FLOWERING LOCUS C (FLC), which prevents flowering until after winter. In contrast, many rapid-cycling accessions have low FLC levels because FRI is inactive. Using biochemical, functional and bioinformatic approaches, we show that FRI and FRL1 contain a stable, central domain that is conserved across the FRI superfamily. This core domain is monomeric in solution and primarily α-helical. We analysed the ability of several FRI deletion constructs to function in Arabidopsis plants. Our findings suggest that the C-terminus, which is predicted to be disordered, is required for FRI to promote FLC expression and may mediate protein:protein interactions. The contribution of the FRI N-terminus appears to be limited, as constructs missing these residues retained significant activity when expressed at high levels. The important N- and C-terminal regions differ between members of the FRI superfamily and sequence analysis identified five FRI families with distinct expression patterns in Arabidopsis, suggesting the families have separate biological roles.