c-MYB oncogene-like genes encoding three MYB repeats occur in all major plant lineages.
Since the identification of the first plant MYB-like protein, the Zea mays factor C1, the number of MYB-related genes described has greatly increased. All of the more than 150 plant MYB-like proteins known so far contain either two or only one sequence-related helix-turn-helix motif in their DNA-binding domain. Animal c-MYB genes contain three such helix-turn-helix motif-encoding repeats (R1R2R3 class genes). It has therefore been concluded that R2R3-MYB genes are the plant equivalents of c-MYB and that there are significant differences in the basic structure of MYB genes of plants and animals. Here, we describe expressed R1R2R3-MYB genes from Physcomitrella patients++ and Arabidopsis thaliana, designated PpMYB3R-1 and AtMYB3R-1. The amino acid sequences of their DNA-binding domains show high similarity to those of animal MYB factors, and less similarity to R2R3-MYB proteins from plants. In addition, R1R2R3-MYB genes were identified in different plant evolutionary lineages including mosses, ferns and monocots. Our data show that a DNA-binding domain consisting of three MYB repeats existed before the divergence of the animal and plant lineages. R1R2R3-MYB genes may have a conserved function in eukaryotes, and R2R3-MYB genes may predominantly regulate plant-specific processes which evolved during plant speciation.
Kranz
H
H
Max-Planck-Institut für Züchtungsforschung, Abteilung Biochemie, Köln, Germany.
Scholz
K
K
Weisshaar
B
B
D000595:Amino Acid Sequence; D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins / Q000235:genetics*; D019143:Evolution, Molecular; D017343:Genes, Plant / Q000235:genetics*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics*; D020598:Proto-Oncogene Proteins c-myb; D012091:Repetitive Sequences, Nucleic Acid; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid
C511988:ATR1 protein, Arabidopsis; D029681:Arabidopsis Proteins; C511989:CPC protein, Arabidopsis; D004268:DNA-Binding Proteins; D010940:Plant Proteins; D020598:Proto-Oncogene Proteins c-myb