Part:BBa_K4629000

Durio zibethinus glutamate-cysteine ligase, chloroplastic

    A plant's stress response is crucial to ensure optimum health when responding to external stressors, such as drought, heat, saltwater intrusion etc… One factor that increases effectiveness of the plant stress response is glutathione (GSH) because it mitigates increased levels of reactive oxygen species (ROS).^[1]. When undergoing oxidative stress, organisms experience increased levels of ROS, which can cause damage to the basic building blocks of the plant cell. Even though accumulation of ROS occurs in many plant organelles, this accumulation of ROS is the most concentrated in the mitochondria and GSH is one of the molecules that helps neutralize their damaging effects. Glutamate-cysteine ligase (GCL), which synthesizes gamma-glutamyl cysteine (γ-EC), is a rate-limiting enzyme in the GSH production pathway that is located in the chloroplast. The GSH then gets transported to the mitochondria to neutralize ROS. In this investigation, our team aimed to relocate the GCL protein from the chloroplast to the mitochondria, so that GSH synthesis would occur in the mitochondria instead. The outcome would be to improve the efficiency of GSH action, thus increasing the stress response in plants. This project is beneficial to the agricultural sector, which in turn is a major source of income for many countries. An improved stress response in crops will increase plant resilience and allow farmers more time to attend to the source of stress before the plants wilt or undergo any other undesirable and significant change, rendering them unsellable.

    Durio zibethinus was used for the project because in its ripe fruit pulp, it contains higher levels of γ-EC and GSH relative to other plants.^[2]. This specific trait suggests that the D. zibethinus may exhibit higher enzyme activity than other plants, contain more enzymes for producing GSH, or have a GCL with higher activity than other plants. For this reason, the team decided to use the GCL gene from this plant.^[3]. D. zibethinus glutamate-cysteine ligase (DzGCL), an enzyme usually located in the chloroplast, was modified to control the majority of the production of (γ-EC)/GSH within the mitochondria instead.

    DzGCL is beneficial for other plant-related projects as D. zibethinus has a high innate level of GSH, making the DzGCL gene a good inspiration for other plant-based science projects that aim to increase efficiency of plant stress response, as high levels of GSH allow for better control of ROS levels.

Annotated Bibliography

1. Hasanuzzaman M, Nahar K, Anee TI, Fujita M. Glutathione in plants: biosynthesis and physiological role in environmental stress tolerance. Physiology and Molecular Biology of Plants. 2017;23:249-68. doi:10.1007/s12298-017-0422-2

2. Singcha P, Khaksar G, Sirijan M, Sirikantaramas S. Durian (Durio zibethinus L.) fruit: A superior dietary source of natural glutathione and γ-glutamylcysteine. SSRN 2023; 4566631. doi:10.2139/ssrn.4566631

3. Pinsorn P, Oikawa A, Watanabe M, Sasaki R, Ngamchuachit P, Hoefgen R, Saito K, Sirikantaramas S. Metabolic variation in the pulps of two durian cultivars: Unraveling the metabolites that contribute to the flavor. Food chemistry. 2018; 268:118-125. doi:10.1016/j.foodchem.2018.06.066

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  COMPATIBLE WITH RFC[21]
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  COMPATIBLE WITH RFC[1000]