Recombinant Manihot esculenta NAD (P)H-quinone oxidoreductase subunit 4L, chloroplastic
Description
Introduction and Overview
Manihot esculenta, commonly known as cassava, is a perennial woody shrub of the Euphorbiaceae family, cultivated extensively in tropical and subtropical regions worldwide. This plant serves as a major source of carbohydrates for over 800 million people globally and demonstrates remarkable resilience to adverse environmental conditions . The photosynthetic efficiency and stress adaptation of cassava are largely attributed to specialized chloroplast proteins, including the NAD(P)H-quinone oxidoreductase complex.
The NAD(P)H-quinone oxidoreductase subunit 4L (ndhE) is a plastid-encoded component of the chloroplast NADH dehydrogenase-like (NDH) complex, which mediates cyclic electron transport and chlororespiration in plants . This protein is critical for optimizing photosynthetic efficiency, particularly under fluctuating light conditions and environmental stresses .
Physical and Chemical Properties
The physical and chemical properties of the recombinant NAD(P)H-quinone oxidoreductase subunit 4L have been characterized extensively. Key properties are summarized in Table 1.
Table 1: Physical and Chemical Properties of Recombinant NAD(P)H-quinone oxidoreductase subunit 4L
| Property | Value |
|---|---|
| Protein Length | 101 amino acids (full length) |
| Molecular Weight | Approximately 24.69 kDa |
| Theoretical Isoelectric Point | Varies (typically in alkaline range) |
| UniProt ID | B1NWK1 |
| Gene Name | ndhE |
| Alternative Names | NAD(P)H dehydrogenase subunit 4L, NADH-plastoquinone oxidoreductase subunit 4L |
| Enzymatic Classification | EC 1.6.5.- |
| Cellular Localization | Chloroplastic, membrane-bound |
Role in Chloroplast NDH Complex
The NAD(P)H-quinone oxidoreductase subunit 4L is an integral component of the chloroplast NADH dehydrogenase-like (NDH) complex, which in angiosperms consists of at least five sub-complexes . This NDH complex mediates cyclic electron transport around photosystem I and is involved in chlororespiration, processes critical for balancing the ATP/NADPH ratio in plant cells .
Research has demonstrated that the NDH complex in cassava, like in other plants, associates with photosystem I to form a super-complex, although the structural organization may vary between species . The ndhE subunit contributes to the core membrane sub-complex of the NDH, facilitating electron transfer within the thylakoid membrane .
Cyclic Electron Transport Mechanism
The cyclic electron transport around photosystem I, in which the NDH complex including the ndhE subunit participates, generates ATP without the accumulation of NADPH in chloroplasts . This process is particularly important under stress conditions when linear electron transport might be limited or when there is an increased demand for ATP relative to NADPH .
The electron transport pathway involves the oxidation of NAD(P)H and the reduction of plastoquinone, contributing to the formation of a proton gradient across the thylakoid membrane that drives ATP synthesis . The NAD(P)H-quinone oxidoreductase complex, including subunit 4L, plays a central role in this process by facilitating the transfer of electrons from reduced ferredoxin back to the plastoquinone pool .
Importance in Plant Adaptation and Stress Response
Studies have revealed that the NDH complex, including the NAD(P)H-quinone oxidoreductase subunit 4L, is particularly important for plant adaptation to various environmental stresses . Research on tobacco plants with deficiencies in NDH subunits (including analogs of ndhE) has shown delayed heat acclimation compared to wild-type plants, suggesting a role for this complex in thermal adaptation .
In cassava, which is often cultivated in marginal lands subject to various stresses, the NDH complex may be especially important for maintaining photosynthetic efficiency under adverse conditions . The genetic diversity in chloroplast coding regions, including those encoding NDH subunits, has been linked to variations in stress tolerance among cassava varieties .
Expression Systems
Recombinant NAD(P)H-quinone oxidoreductase subunit 4L from Manihot esculenta can be produced using various expression systems. The two primary systems employed are:
Purification and Characterization Methods
The recombinant NAD(P)H-quinone oxidoreductase subunit 4L is typically purified using affinity chromatography, leveraging the His-tag incorporated during expression . The purified protein is then subjected to SDS-PAGE analysis to confirm its molecular weight and purity, with quality standards typically requiring >85% purity .
Further characterization may involve mass spectrometry, circular dichroism spectroscopy, and functional assays to assess the protein's structural integrity and enzymatic activity . Blue-native gel electrophoresis has also been employed to study the integration of the protein into the NDH complex and its association with other subunits .
Applications in Research and Biotechnology
The recombinant NAD(P)H-quinone oxidoreductase subunit 4L has several important applications in research and potential applications in biotechnology:
Photosynthesis Research
The protein serves as a valuable tool for studying cyclic electron transport and the role of the NDH complex in photosynthesis . By using the recombinant protein in reconstitution experiments or as a standard in proteomic analyses, researchers can gain insights into the structure and function of the NDH complex in different plant species and under various environmental conditions .
Crop Improvement Studies
Understanding the role of NDH subunits, including NAD(P)H-quinone oxidoreductase subunit 4L, in stress adaptation has implications for crop improvement programs . Research on genetic diversity in chloroplast coding regions of cassava has revealed potential targets for enhancing resistance to biotic and abiotic stresses .
For example, studies on cassava chloroplast genomics have identified considerable genetic diversity in NDH-related genes among cultivated varieties from East Africa, suggesting potential for selecting varieties with enhanced stress tolerance based on NDH complex composition .
Biotechnological Applications
The thermostability and catalytic properties of NAD(P)H-quinone oxidoreductases make them potentially valuable for biotechnological applications . While research on the specific applications of the subunit 4L is limited, related quinone oxidoreductases have been explored for:
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Bioremediation of quinone-containing pollutants
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Biosensors for detecting quinones and related compounds
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Biocatalysis in industrial processes requiring redox reactions under stringent conditions
Comparative Analysis with Related Proteins
The NAD(P)H-quinone oxidoreductase subunit 4L from Manihot esculenta shares structural and functional similarities with homologous proteins from other plant species. Comparative analysis reveals conservation of key functional domains while also highlighting species-specific adaptations .
The conservation of ndhE and other NDH subunits across diverse plant lineages underscores the evolutionary importance of the NDH complex in plant adaptation and survival . Variations in these genes may contribute to the different ecological adaptations observed among plant species, including the remarkable stress tolerance of cassava .
Future Research Directions
Future research on the NAD(P)H-quinone oxidoreductase subunit 4L from Manihot esculenta and its role in the NDH complex is likely to focus on several key areas:
Product Specs
Note: We prioritize shipping the format currently in stock. However, if you have a specific format requirement, please indicate it in your order notes. We will fulfill your request if possible.
Note: Our proteins are shipped with standard blue ice packs. If you require dry ice shipment, please inform us in advance. Additional fees will apply.
Generally, liquid forms have a shelf life of 6 months at -20°C/-80°C. Lyophilized forms have a shelf life of 12 months at -20°C/-80°C.
