Fig. 3. Contribution of conserved cysteines to the ROXY1 function in petal
development. (A) Alignment of open reading frames from GRXs of different
species. Identical amino acids are in dark shading, similar ones in light
shading. Two cysteines in the active site CXXC, conserved among all GRXs, are
indicated by arrows (C49, C52). Another cysteine at position 90 (C90) is part
of a putative monothiol CXXS motif specific to ROXY1. (B-E) Complementation
analysis of mutagenized ROXY1 cysteines. roxy1-3 mutants were
transformed with the wild-type (B) and mutagenized ROXY1 genes, where
the three cysteines C49, C50 and C90 were exchanged into serines (C-E) and
expressed under the control of the 35S promoter. (B) Wild-type protein
complements 41/64 transgenic T1 roxy1-3 plants. (C) Mutagenesis of
the N-terminal cysteine in the dithiol motif (C49S) disables the
complementation capacity of the protein. C49S plants (88/92 T1 plants)
resemble the roxy1-3 mutant. (D,E) C52S and C90S proteins were able
to restore over 50% of the T1 roxy1-3 mutants (35/68 and 37/54,
respectively), forming flowers with almost wild-type like petals. Photographs
show representative inflorescences from transgenic T1 plants. Accession
Numbers: E. coli, NP_415370