Dylan

Myb Transcription Factors

Myb is actually an acronym taken from “myeloblastosis,” an old name for a certain type of leukemia. Studies have established that the absence of Myb proteins causes an increase in mitotic arrest, abnormal chromosome number, and faulty spindle formation. The protein localizes to recently replicated DNA in mitotically cycling and endocycling cells, regulating gene expression by binding directly to the DNA. The graphic representation below shows the helical structure of the protein (light blue) as it works in the cell: fitting into the major groove of the DNA double helix (red and yellow).[1]

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Myb Protein Structure

Myb proteins are defined by the aptly named Myb domain, a sequence of approximately 50 amino acids. They are further divided into three subfamilies based on the number of times that this domain repeats. The protein may have one (designated ‘MYB1R’), two (‘R2R3-MYB’), or three (‘MYB3R’) sets of these repeats.[3] The repeat domains are highly conserved; analysis of diverse eukaryotic organisms has determined that each Myb repeat is more closely related to other members of the same family than to other repeats within the same protein.[4]

Myb Transcription Factors in Plants

A study conducted by Ban et al. explored the function of the Myb transcription factors in apples. The study focused on the regulation of anthocyanins, a member of the flavonoid family that, among other things, gives the fruit its red color.[5] Myb proteins were believed prior to this study to have some control over anthocyanin expression,[6] so Ban and his partners chose it as their primary topic. The health benefits of anthocyanin are potentially great, with laboratory results suggesting positive effects against cancer, aging and neurological diseases, inflammation, diabetes, and bacterial infections.[7] Unfortunately, anthocyanin is poorly conserved in the body during digestion; less than 5% of the starting mass is properly absorbed.[8] Therefore, any treatment using this chemical would need to be specially treated and perhaps in exceptionally high concentration. Knowledge of the Myb transcription factors could help to produce this chemical quickly and cheaply from modified plants.