Phylogenetic analysis of plant basic helix-loop-helix proteins

• Published in: Journal of molecular evolution Vol. 56; no. 6; pp. 742 - 750
• Main Authors: Buck, Michael J, Atchley, William R
• Format: Journal Article
• Language: English
• Published: Germany Springer Nature B.V 01.06.2003
• Subjects: Amino Acid Sequence; Animals; Arabidopsis - genetics; Biosynthesis; Genetics; Genome, Plant; Helix-Loop-Helix Motifs; Molecular Sequence Data; Multigene Family; Oryza - genetics; Phylogeny; Plant biology; Plant Proteins - chemistry; Plant Proteins - genetics; Plant species; Proteins; Rice; Transcription Factors - chemistry; Transcription Factors - genetics
• ISSN: 0022-2844; 1432-1432
• DOI: 10.1007/s00239-002-2449-3

The basic helix-loop-helix (bHLH) family of proteins is a group of functionally diverse transcription factors found in both plants and animals. These proteins evolved early in eukaryotic cells before the split of animals and plants, but appear to function in 'plant-specific' or 'animal-specific' processes. In animals bHLH proteins are involved in regulation of a wide variety of essential developmental processes. On the contrary, bHLH proteins have not been extensively studied in plants. Those that have been characterized function in anthocyanin biosynthesis, phytochrome signaling, globulin expression, fruit dehiscence, carpel and epidermal development. We have identified 118 different bHLH genes in the completely sequenced Arabidopsis thaliana genome and 131 bHLH genes in the rice genome. Here we report a phylogenetic analysis of these genes, including 46 genes from other plant species and a classification of these proteins into 15 distinct plant clades. Results imply a polyphyletic origin for the plant bHLH proteins related only by their bHLH DNA binding motif. We suggest that plant bHLH proteins are under weaker selective constraints than their animal counterparts and that lineage specific expansions and subfunctionalization have fashioned regulatory proteins for plant specific functions.