Plants And Animals Fix DNA Differently

Unlike animals, the mechanism of DNA repair in plants is skewed towards homologous recombination and involved in their immune response to fungal infections.

AsianScientist (Mar. 7, 2018) – In a study published in the Plant Journal, scientists at the Nara Institute of Science and Technology (NAIST) in Japan have found that plants and animals deal with DNA damage in different ways.

In mammalian cells, DNA damage leads to a cascade of molecular events that eventually activate p53, which ensures that DNA damage gets repaired. If the DNA damage is irreparable, the cell dies. The equivalent of p53 in plants is called the suppressor of gamma response 1 (SOG1), even though it does not share a common evolutionary ancestor with p53. While p53 has been exhaustively studied, much less is known about SOG1.

In this study, researchers at NAIST led by Professor Masaaki Umeda used the popular laboratory plant model Arabidopsis to show that SOG1 is only phosphorylated and activated upon DNA damage. The phosphorylated SOG1 then binds to promoters of many genes which are responsible for DNA repair and cell division.

However, while both SOG1 and p53 target DNA repair genes, SOG1 showed a higher affinity for genes that conducted repair through homologous recombination. Additional experiments revealed that a specific palindromic DNA sequence in the target gene promoters was crucial for SOG1 binding.

“Considering that SOG1 and p53 regulate different sets of DNA repair-related genes, it is probable that plants and animals have distinct tendencies for activating DNA repair pathways,” Umeda explained.

Interestingly, while the majority of SOG1 target genes were involved in DNA repair and cell cycle control, a significant subset responded to fungal pathogen invasion, but not bacterial infection. In contrast, p53 does not play a significant immune role in animal cells. Why SOG1 targets genes that elicit an immune response only to fungal infection (even though DNA damage occurs regardless of the pathogen) is an open question that deserves further study.

Umeda believes that understanding the SOG1 gene targets and the SOG1 immune function could allow for better farming through the modulation of DNA damage signaling.

“Environmental factors can cause DNA damage, which activates SOG1. If we are able to control this activation, we could control the growth of agricultural products,” said Umeda.

The article can be found at: Ogita et al. (2018) Identifying the Target Genes of SUPPRESSOR OF GAMMA RESPONSE 1, a Master Transcription Factor Controlling DNA Damage Response in Arabidopsis.


Source: Nara Institute of Science and Technology; Photo: Shutterstock.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

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