High impact information on ATCUL1

• We propose that RBX1 functions as an E3 for RUB modification of CUL1 [1].
• In Arabidopsis, RUB modification of CUL1 is required for normal function of SCF(TIR1), an E3 required for response to the plant hormone auxin [1].
• Arabidopsis AXR6 encodes CUL1 implicating SCF E3 ligases in auxin regulation of embryogenesis [2].
• In addition, we show that CUL1 has a role in auxin response throughout the life cycle of the plant [2].
• These results indicate that the embryonic axr6 phenotype is related to a defect in SCF function and accumulation of Aux/IAA proteins such as BDL/IAA12 [2].

Biological context of ATCUL1

• The SCF core components Skp1, Cul1, and Rbx1 serve in multiple SCF complexes involving different substrate-specific F-box proteins that are involved in diverse processes including cell cycle and development [3].
• Plants homozygous for a point mutation in the AtCUL1 gene showed reduced floral organ number and several defects in each of the four whorls [3].
• SKP1/ASK1, cullin and proteasomal alpha-subunits show nuclear co-localization in differentiated Arabidopsis cells, and are observed in association with mitotic spindles and phragmoplasts during cell division [4].
• The requirement of CUL1 for Arabidopsis embryogenesis suggests that Skp1-CUL1-F-box protein (SCF) complexes play important roles during embryo development [5].
• We describe two mutants of Arabidopsis that define a novel gene called AUXIN-RESISTANT6 (AXR6) which maps to chromosome 4 [6].

Associations of ATCUL1 with chemical compounds

• The regulation of EIN3 stability by ethylene is accomplished by F-box-containing proteins that participate in the formation of a SKP1/cullin/F-box complex that targets proteins for degradation by the proteasome [7].

Physical interactions of ATCUL1

• In the absence of ethylene, EIN3 and possibly other EIL proteins are targeted for ubiquitination and subsequent degradation by Cullin 1-based E3 complexes containing EBF1 and 2 [8].

Other interactions of ATCUL1

• Furthermore, the genetic interaction between UFO and AtCUL1 supports the idea that UFO regulates multiple aspects of flower development as a part of SCF complexes [3].
• Furthermore, we demonstrate that CSN interacts with CUL3, in addition to CUL1 and CUL4, and that the lack of CSN activity differentially affects the stability of those three cullins [9].
• In this work Arabidopsis cullin 4 is shown to assemble with DDB1, RBX1, DET1 and DDB2 in vitro and in planta [10].
• The Arabidopsis cullin AtCUL1 is modified by the ubiquitin-related protein RUB1 [11].
• These results suggest that the COI1-mediated JA response is dependent on the SCF(COI1) complexes in Arabidopsis and that the AXR1-dependent modification of the AtCUL1 subunit of SCF(COI1) complexes is important for JA signaling [12].

References