Unequally redundant RCD1 and SRO1 mediate stress and developmental responses and interact with transcription factors

Abstract

RADICAL-INDUCED CELL DEATH1 (RCD1) is an important regulator of stress and hormonal and developmental responses in Arabidopsis thaliana. Together with its closest homolog, SIMILAR TO RCD-ONE1 (SRO1), it is the only Arabidopsis protein containing the WWE domain, which is known to mediate protein-protein interactions in other organisms. Additionally, these two proteins contain the core catalytic region of poly-ADP-ribose transferases and a conserved C-terminal domain. Tissue and subcellular localization data indicate that RCD1 and SRO1 have partially overlapping functions in plant development. In contrast mutant data indicate that rcd1 has defects in plant development, whereas sro1 displays normal development. However, the rcd1 sro1 double mutant has severe growth defects, indicating that RCD1 and SRO1 exemplify an important genetic principle - unequal genetic redundancy. A large pair-wise interaction test against the REGIA transcription factor collection revealed that RCD1 interacts with a large number of transcription factors belonging to several protein families, such as AP2/ERF, NAC and basic helix-loop-helix (bHLH), and that SRO1 interacts with a smaller subset of these. Full genome array analysis indicated that in many cases targets of these transcription factors have altered expression in the rcd1 but not the sro1 mutant. Taken together RCD1 and SRO1 are required for proper plant development.

Footprints of divergent selection in natural populations of Castanopsis fargesii (Fagaceae)

“…The locus CC2448 was functionally assigned to Poly-ADP-ribose transferase. Radical-induced cell death1 (RCD1) and proteins similar to RCD1, which contained the core catalytic domain of poly-ADPribose transferase, were important regulators of stress and developmental responses in plants (Jaspers et al, 2009). Our results suggested that this locus might be involved in climatic adaptation of C. Fargesii, especially associated with climatic extremes such as precipitation of driest and coldest quarter.…”

Arabidopsis STO/BBX24 negatively regulates UV-B signaling by interacting with COP1 and repressing HY5 transcriptional activity

“…While RUP1/RUP2 negatively regulate UV-B signaling by interacting with UVR8 [24], the BBX24 protein fine-tunes the UV-B responses by impinging on HY5. The BBX24-interacting protein RCD1 [19] , supplemented with white light. UV-B radiation from the lamps was filtered through cellulose acetate film to block potential UV-C (+UV-B).…”

“…The expression of COP1-regulated UV-B responsive genes was enhanced in rcd1-1 mutant under UV-B radiation, indicating that RCD1 negatively regulates UV-B response [18]. Interestingly, RCD1 interacts with STO/BBX24 in vitro [19]. These findings prompted us to test whether STO/BBX24 functions in UV-B photomorphogenic responses.…”

The BBX subfamily IV

“…53,54 Nagaoka and Takano (2003) showed that Arabidopsis plants overexpressing BBX24 had an enhanced tolerance to salty media. 55 BBX24 interacts in yeast-two-hybrid assays with the hormone and abiotic stress regulator CLONE EIGHTY-ONE/ RADICAL INDUCED CELL DEATH1 (CEO/RCD1) 56,57 and with COP1, a negative regulator of photomorphogenesis. 58 Holm and colleagues (2001) described a conserved amino-acid motif shared by BBX24, BBX25 and HY5 (V-P-E/D-Φ-G; Φ = hydrophobic residue) which is needed for a correct interaction with the WD40 domain of COP1.…”