Crystal structure of the MYB domain of the RAD transcription factor from Antirrhinum majus.
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Amino Acid Sequence↗
Biomedical subjects
Enrico S Coen
Publications and source records attributed to Enrico S Coen.
Crystallization and preliminary X-ray analysis of the RAD protein from Antirrhinum majus.
Crystals of the RADIALIS protein from Antirrhinum majus were grown by vapour diffusion after limited proteolysis. Mass spectrometry indicated that an 8 kDa fragment had been crystallized corresponding to the predicted MYB DNA-binding domain. X-ray data collected at room temperature were consistent with tetragonal symmetry, whereas data collected at 100 K using crystals cryoprotected by supplementing the mother liquor with ethylene glycol conformed to orthorhombic symmetry. It was subsequently shown that crystals soaked in cryoprotectants that were ;osmolality-matched' to the mother liquor retained tetragonal symmetry. Using these crystals, X-ray data were collected in-house to a maximum resolution of 2 A.
Antirrhinum↗
CINCINNATA controls both cell differentiation and growth in petal lobes and leaves of Antirrhinum.
To understand how differentiation and growth may be coordinated during development, we have studied the action of the CINCINNATA (CIN) gene of Antirrhinum. We show that in addition to affecting leaf lamina growth, CIN affects epidermal cell differentiation and growth of petal lobes. Strong alleles of cin give smaller petal lobes with flat instead of conical cells, correlating with lobe-specific expression of CIN in the wild type. Moreover, conical cells at the leaf margins are replaced by flatter cells, indicating that CIN has a role in cell differentiation of leaves as well as petals. A weak semidominant cin allele affects cell types mainly in the petal but does not affect leaf development, indicating these two effects can be separated. Expression of CIN correlates with expression of cell division markers, suggesting that CIN may influence petal growth, directly or indirectly, through effects on cell proliferation. For both leaves and petals, CIN affects growth and differentiation of the more distal and broadly extended domains (leaf lamina and petal lobe). However, while CIN promotes growth in petals, it promotes growth arrest in leaves, possibly because of different patterns of growth control in these systems.
Alleles↗
Interactions between gene activity and cell layers during floral development.
The DEFICIENS (DEF) gene is required for establishing petal and stamen identity in Antirrhinum and is expressed in all three layers of the floral meristem in whorls 2 and 3. Expression of DEF in a subset of meristem layers gives rise to organs with characteristic shapes and cell types, reflecting altered patterns and levels of DEF gene activity. To determine how the contributions of layers and gene activity interact, we exploited a DEF allele which carries a transposon insertion in the MADS box region to generate periclinal chimeras expressing alleles with different activities. By comparing the phenotype, development and expression patterns of these chimeras we show that expression of DEF in L1 makes a major contribution to morphology in whorl 2, irrespective of the allele. By contrast L1 expression is largely unable to rescue whorl 3, possibly because of a non-autonomous inhibitor of DEF activity in this whorl.
Alleles↗
The cycloidea gene can respond to a common dorsoventral prepattern in Antirrhinum.
Dorsoventral asymmetry in flowers of Antirrhinum depends on expression of the cycloidea gene in dorsal regions of floral meristems. To determine how cycloidea might be regulated we analysed its expression in several contexts. We show that cycloidea is activated shortly after floral induction, and that in addition to flowers, cycloidea can be asymmetrically expressed in shoots, even though these shoots show no marked dorsoventral asymmetry. Shoots expressing cycloidea include secondary branches lying just below the inflorescence, and shoots of floricaula mutants. Asymmetric cycloidea expression may also be observed within organ primordia, such as the sepals of terminal flowers produced by centroradialis mutants. Later expression of cycloidea within flowers can be modified by mutations in organ identity genes. Taken together, the results suggest that cycloidea can respond to a common dorsoventral pre-pattern in the apex and that the specific effects of cycloidea on the flower depend on interactions with floral-specific genes.
DNA-Binding Proteins↗