MYB

Brief Introduction

• The MYB gene family is one of the largest groups of transcription facotrs in plants. MYB genes are classified into four major groups, including 1R-MYB, 2R-MYB, 3R-MYB and 4R-MYB with one, two, three and four MYB repeats, respectively. Each repeat contains approximately 50–53 amino acids and forms a helix-turn-helix fold with three regularly spaced tryptophan residues. Moreover, each repeat contains regularly spaced tryptophan residues, forming a tryptophan cluster in the 3-dimensional HTH structure.

Figure 1. Gene structure of Os05g0195700 (R1-MYB)

• The R1R2R3-type MYB domain proteins with three MYB repeats are predominant in animals, while the most common type of MYB transcription factor in plants is R2R3-MYB with two MYB repeats.

Figure 2. Gene structure of BGIOSGA001907. (R2R3-MYB)

Figure 3. Gene structure of BGIOSGA017917. (R1R2R3-MYB)

• Although some previous study suggested that MYB TFs in plants play a key role in secondary metabolism, hormone signal transduction, cellular morphogenesis, disease resistance and abiotic stress tolerance, the precise functions of most plant Myb genes are still rarely known.
• So far, no 4R-MYB genes were found through rice genome, neither in Japonica Group nor Indica Group. However, a very special MYB gene Os07g0139500 with more than four MYB repeats were identified by our RiceWiki Curation Team using NCBI BLASTP (Figure 4). And its particular 5R-MYB-structure was further acknowledged by HMM Tools (Figure 5) as well as SMART(Simple Modular Architecture Research Tool) (Figure 6). Of course, more molecular biological studies are required for confirming the existence of 5R-MYB genes in plants.

Figure 4. Gene structure of Os07g0139500 (Potential R5-MYB)

Figure 5. The result of HMM search for Os07g0139500

Figure 6. The result of SMART for Os07g0139500

• Pfam: PF00249 || InterPro: IPR001005 ||