Disease relevance of SUP

• Constitutive expression of SUPERMAN resulted in a severe dwarfism but did not affect cell size, indicating that SUPERMAN might regulate genes that are involved in cell division [1].

High impact information on SUP

• The putative SUPERMAN protein contains one zinc-finger and a region resembling a basic leucine zipper motif, suggesting a function in transcriptional regulation [2].
• These cmt3 mutants display a wild-type morphology but exhibit decreased CpXpG methylation of the SUP gene and of other sequences throughout the genome [3].
• Seven heritable but unstable sup epi-alleles (the clark kent alleles) are associated with nearly identical patterns of excess cytosine methylation within the SUP gene and a decreased level of SUP RNA [4].
• The pattern of PI expression also depends on the activity of the floral development genes APETALA2 and SUPERMAN and on the activity of PI itself [5].
• The petunia ortholog of Arabidopsis SUPERMAN plays a distinct role in floral organ morphogenesis [6].

Biological context of SUP

• The association of both an N-terminal and a C-terminal basic region with a single Cys2-His2 zinc finger represents a novel DNA-binding motif suggesting that the mechanism of DNA recognition adopted by the SUP protein is different from that described so far in other zinc finger proteins [7].
• The Arabidopsis SUPERMAN (SUP) gene has been shown to be important in maintaining the boundary between stamens and carpels, and is presumed to act by regulating cell proliferation [7].
• Furthermore, amino acid substitutions in the zinc finger or in the basic regions, including a mutation that knocks out the function of the SUP protein in vivo (glycine 63 to aspartate), have been found to abolish the activity of the SUP DNA-binding domain [7].
• Essentially additive phenotypes are observed in superman agamous and superman apetala2 double mutants [8].
• SUPERMAN, a regulator of floral homeotic genes in Arabidopsis [8].

Anatomical context of SUP

• Together with our previous study of FON1, these results clearly indicate that the FON1-FON2 system in rice corresponds to the CLV signaling system in Arabidopsis and suggest that the negative regulation of stem cell identity by these systems may be principally conserved in a wide range of plants within the Angiosperms [9].

Associations of SUP with chemical compounds

• Here, we report the synthesis and UV and NMR spectroscopic structural characterization of a 37 amino acid SUPERMAN region complexed to a Zn(2+) ion (Zn-SUP37) and present the first high-resolution structure of a classical zinc finger domain from a plant protein [10].
• The SUP gene encodes a transcription factor with a C2H2-type zinc finger motif, a serine/proline-rich domain, a basic domain, and a leucine-zipper-like domain and is expressed in a very limited region in stamen primordia and in the developing ovary during flower development [11].
• The gene FLORAL ORGAN NUMBER1 regulates floral meristem size in rice and encodes a leucine-rich repeat receptor kinase orthologous to Arabidopsis CLAVATA1 [12].
• Comparison of the methylated sequences in SUPERMAN and AGAMOUS suggests that hypermethylation could involve DNA secondary structures formed by pyrimidine-rich sequences [13].
• In contrast, segregants lacking the METI antisense construct and epimutants with a hypermethylated allele of sup (clark kent 3), both of which have active METI genes, showed a higher frequency of methylation of CpG dinucleotides and of asymmetric cytosines [14].

Regulatory relationships of SUP

• We cloned ARGONAUTE4 (AGO4) from a screen for mutants that suppress silencing of the Arabidopsis SUPERMAN (SUP) gene [15].
• Microscopic observations revealed that the innermost-whorl carpels had been replaced by stamen-like organs, which resembled the flowers of the previously described Arabidopsis thaliana (L.) Heynh. mutation superman as well as those ectopically expressing the AP3 gene [16].

Other interactions of SUP

• The spatial pattern of AGAMOUS expression remains unaltered in superman flowers as compared to wild-type flowers [8].
• In addition, superman mutants exhibit a loss of determinacy of the floral meristem, an effect that appears to be mediated by the APETALA3 and PISTILLATA gene products [8].
• However, SUP does not act merely through UFO, as constitutive expression of UFO did not rescue the defects in petal and stamen development in AP1::SUP flowers [17].
• Thus, drm mutants prevent the establishment but not the maintenance of gene silencing at FWA and SUP, suggesting that the DRMs encode the major de novo methylation enzymes affecting these genes [18].
• We suggest that the extensive SUP methylation in car has arisen from an abundant methylation of a single CpG site that was already present in abscisic acid-insensitive (abi3-4) mutants, from which car was segregating [19].

Analytical, diagnostic and therapeutic context of SUP

• The development of superman flowers, from initial primordium to mature flower, is described by scanning electron microscopy [8].
• Through allelism test with fon1-3 and analysis of the methylation state of the SUPERMAN (SUP) gene in car mutants, we show that car is an epi-mutation of SUP [19].

References