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Fig. 8. Inclusion of feedback regulatory reactions on AP2 and miR172. A) SEP3 binding patterns at 3
miR172
loci as revealed
by ChIP-seq. The ChIP-seq peaks are shown in the upper panel in each figure, with genomic loci indicated beneath. In all
cases, the main peak is downstream of and close to the locus. B) Potential regulatory interactions of different complexes on
AP2
and
miR172
loci which were added to our model. For simplification, the 3 different miRNA loci are treated as one entity
in our model. C) (Bottom left) A transcriptional activation process was added between the petal complex (AP1/SEP/AP3/PI)
and
AP2
, leading to the sustained expression of
AP2
in the petal. The presence of AP2 in sepals and petals would add a
redundant repression control on
AG
. (Bottom right) Activation of
miR172
by the stamen complex (AG/SEP3/AP3/PI). The
explicit maintenance of
miR172
expression by the stamen complex allows the translational inhibition of AP2, and thus stabilizes
the expression of
AG
.
suggests that SEP proteins as mediators of higher-order complex formation are required to integrate
and balance the expression of different homeotic proteins, in order to produce stable floral structures.
Experimental quantification of differences in protein interaction preferences and DNA-binding affinity,
as well as specific levels of activation by certain proteins/complexes, would help to clarify the role of
