Recombinant Arabidopsis thaliana ATP synthase subunit a-1 (ATP6-1)
Description
Functional Role in ATP Synthase
ATP6-1 is a membrane-embedded subunit of the FF ATP synthase complex, facilitating proton transport during ATP synthesis . Key functional insights include:
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Gene Disruption Studies: Targeted deletion of mitochondrial atp6-1 via mitoTALENs caused homoplasmic mitochondrial genome edits, demonstrating its indispensability for ATP synthase assembly .
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Subunit Stability: Knockdown of atp1 (a related ATP synthase subunit) reduced Atp1 levels to 15–20% of wild-type, destabilizing the FF complex and lowering ATP synthesis rates by 44–57% .
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Structural Conservation: Mutations in homologous residues of yeast subunit a (e.g., G184S, H185R) impaired ATP synthase activity, underscoring evolutionary conservation in proton channel function .
Research Applications
Recombinant ATP6-1 is pivotal for:
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Protein-Protein Interaction Studies: Mapping interactions within ATP synthase subunits .
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Enzyme Assembly Analysis: Investigating F sector assembly defects in mitochondrial mutants .
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Biochemical Assays: SDS-PAGE validation and oligomerization studies using purified protein .
ATP Synthase Depletion Phenotypes
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Growth Impairment: Arabidopsis lines with reduced ATP6-1 levels exhibited delayed vegetative growth and reduced fertility, mimicking phenotypes of nuclear ATP synthase subunit mutants .
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Metabolic Adaptation: Despite 5-fold Atp1 depletion, cellular ATP/ADP ratios and energy charge remained stable, suggesting compensatory mechanisms in amino acid metabolism .
Mitochondrial Genome Engineering
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MitoTALEN Efficacy: Disruption of atp6-1 using mitoTALENs validated its role in mitochondrial genome stability and provided a template for plant mitochondrial gene editing .
Future Directions
Product Specs
Note: While we prioritize shipping the format currently in stock, we are happy to accommodate any specific format requirements. Please indicate your preference in the order notes, and we will fulfill your request to the best of our ability.
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Generally, liquid forms have a shelf life of 6 months at -20°C/-80°C. Lyophilized forms typically have a shelf life of 12 months at -20°C/-80°C.
Target Background
Q&A
What is the localization and function of ATP synthase subunit a-1 (ATP6-1) in Arabidopsis thaliana?
ATP6-1 is primarily localized in the mitochondria as one of two isoforms (ATP6-1 and ATP6-2) of the ATP synthase subunit 6 gene in Arabidopsis thaliana. It functions as an essential component of the mitochondrial F1Fo ATP synthase complex, which is responsible for ATP production through oxidative phosphorylation. This protein is encoded by the mitochondrial genome, although there is also a nuclear pseudogene copy of atp6-1. The mitochondrial ATP synthase complex plays a crucial role in energy metabolism, and disruption of ATP6-1 can significantly impact plant growth and development .
How can ATP6-1 be distinguished from its nuclear pseudogene counterpart?
Distinguishing the mitochondrial ATP6-1 from its nuclear pseudogene requires careful experimental design. Researchers have successfully used targeted gene disruption approaches to confirm the identity of the mitochondrial gene versus the nuclear pseudogene. When using techniques like mitoTALENs to target the mitochondrial gene, confirmation can be achieved through:
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Isolation of intact mitochondria followed by PCR amplification and sequencing
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Analysis of transcript levels from both mitochondrial and nuclear genomes
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Phenotypic assessment of plants with disrupted mitochondrial ATP6-1
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Protein analysis using antibodies specific to the mitochondrially-encoded ATP6-1
As demonstrated in targeted gene disruption studies, researchers were able to confirm that the mitochondrial gene and not the nuclear pseudogene was knocked out by analyzing the mitochondrial genome in a homoplasmic state .
What techniques are available for studying ATP6-1 expression and function?
Several techniques have proven effective for studying ATP6-1:
| Technique | Application | Advantages |
|---|---|---|
| mitoTALENs | Targeted gene disruption | Allows specific targeting of mitochondrial genes |
| RNA knockdown using PPR proteins | Reduction of ATP6-1 mRNA | Less drastic than complete gene deletion, allows studying partial loss of function |
| Protein tagging (e.g., HA tag) | Protein localization | Enables visualization of ATP6-1 in cellular compartments |
| Yeast two-hybrid analysis | Protein-protein interactions | Identifies assembly factors and interaction partners |
| Quantitative mass spectrometry | Protein abundance | Measures changes in ATP synthase complex components |
Each of these methods provides unique insights into ATP6-1 function. For example, RNA knockdown approaches using custom-designed PPR proteins have been shown to successfully decrease ATP synthase abundance without completely eliminating it, allowing plants to survive while exhibiting altered phenotypes like delayed growth and reduced fertility .
How does targeted disruption of ATP6-1 affect mitochondrial function and plant phenotype?
Targeted disruption of ATP6-1 has profound effects on both mitochondrial function and whole-plant phenotype:
Mitochondrial Function:
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Significant decrease in ATP synthesis rate (44-57% slower in knockdown lines)
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Reduced abundance of assembled F1Fo ATP synthase complexes
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Compensatory changes in other mitochondrial components
Plant Phenotype:
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Delayed vegetative growth
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Reduced fertility
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Higher respiratory rates in leaves
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Elevated steady-state levels of numerous amino acids, particularly those of the serine family
Despite these significant changes, ATP6-1-depleted plants maintain relatively normal adenylate levels and energy charge, suggesting compensatory mechanisms that preserve cellular energy homeostasis. Transcriptomic analyses reveal upregulation of genes involved in amino acid transport and various stress response pathways, indicating cellular adaptations to ATP synthase depletion .
What role do assembly factors play in ATP6-1 incorporation into the ATP synthase complex?
Assembly of ATP6-1 into the functional ATP synthase complex requires specific chaperones and assembly factors. Two key assembly factors are:
Atp11:
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Present in both chloroplasts and mitochondria in Arabidopsis
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Specifically interacts with the β subunit (ATP2) of mitochondrial ATP synthase
Atp12:
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Localized exclusively in mitochondria
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Specifically interacts with the α subunit (ATP1) of mitochondrial ATP synthase
These assembly factors function similarly to their homologs in yeast and humans, suggesting evolutionary conservation of ATP synthase assembly mechanisms. Yeast two-hybrid analyses confirmed that Atp11 specifically interacts with the β subunit and Atp12 interacts with the α subunit of the mitochondrial ATP synthase, indicating their crucial roles in the proper assembly of the complex .
How can mitoTALENs be optimized for efficient targeting of ATP6-1 in Arabidopsis?
Optimizing mitoTALENs for ATP6-1 targeting involves several critical considerations:
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Promoter selection: The RPS5A promoter has proven most effective for mitoTALEN expression in Arabidopsis compared to other tested promoters
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TALEN design: Conventional mitoTALENs are more effective than single-molecule mito-compactTALENs for targeting mitochondrial genes in Arabidopsis
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Transformation method: Both floral-dip transformation and crossing approaches have been successfully used to introduce mitoTALEN constructs
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Screening strategy: PCR-based screening followed by sequencing is essential to identify plants with successful gene disruption
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Homoplasmy confirmation: Since plant mitochondria contain multiple genome copies, confirming complete (homoplasmic) gene disruption is critical
Successful ATP6-1 targeting typically results in large (kb-size) deletions, with the ends of remaining sequences connected to distant loci through illegitimate homologous recombinations between repeats .
What molecular mechanisms explain the metabolic adaptations observed in ATP6-1-depleted plants?
Plants with depleted ATP6-1 undergo significant metabolic adaptations to compensate for reduced ATP synthase activity:
The primary adaptive mechanisms include:
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Altered amino acid metabolism: ATP6-1-depleted plants show elevated levels of multiple amino acids, particularly those in the serine family, suggesting a metabolic shift to compensate for energy deficiency
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Transcriptional reprogramming: Differential expression of genes related to amino acid transport and stress responses occurs to maintain cellular homeostasis
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Respiratory adjustments: Higher respiratory rates in leaves indicate potential uncoupling or alternative electron transport pathways to compensate for ATP synthase deficiency
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Adenylate homeostasis: Despite reduced ATP synthesis capacity, plants maintain near-normal ATP/ADP ratios (approximately 1.8) and adenylate charge (approximately 0.8), suggesting powerful compensatory mechanisms to preserve energy balance
These adaptations demonstrate the remarkable plasticity of plant metabolism and the existence of regulatory networks that sense and respond to perturbations in mitochondrial function.
How does ATP6-1 differ from ATP6-2 in terms of function and regulation?
While both ATP6-1 and ATP6-2 encode isoforms of the ATP synthase subunit 6 in Arabidopsis mitochondria, they exhibit several differences:
| Characteristic | ATP6-1 | ATP6-2 |
|---|---|---|
| Nuclear pseudogene | Present | Not reported |
| Tissue expression pattern | Potentially different from ATP6-2 | Potentially different from ATP6-1 |
| Response to targeted disruption | Can be individually deleted | Can be individually deleted |
| Compensatory capacity | Other subunits may partially compensate | Other subunits may partially compensate |
What experimental approaches can be used to study the interaction between ATP6-1 and other ATP synthase subunits?
Several sophisticated approaches can be employed to study interactions between ATP6-1 and other ATP synthase subunits:
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Blue native polyacrylamide gel electrophoresis (BN-PAGE): Enables visualization of intact ATP synthase complexes and subcomplexes to assess the impact of ATP6-1 modifications
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Co-immunoprecipitation with tagged ATP6-1: Allows identification of direct interaction partners
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Cryo-electron microscopy: Provides structural insights into the integration of ATP6-1 within the complex
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Protein crosslinking followed by mass spectrometry: Identifies proximity relationships between ATP6-1 and neighboring subunits
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Yeast two-hybrid analysis: As demonstrated with ATP synthase assembly factors, this approach can reveal specific interactions between ATP6-1 and other proteins
Example from research: Yeast two-hybrid analyses have shown that assembly factors like Atp11 and Atp12 specifically interact with particular subunits of ATP synthase (β and α subunits, respectively), suggesting similar approaches could be applied to study ATP6-1 interactions .
How can custom-designed RNA-binding proteins be optimized for ATP6-1 knockdown studies?
Custom-designed RNA-binding pentatricopeptide repeat (PPR) proteins offer a powerful approach for ATP6-1 knockdown studies. Optimization strategies include:
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Target sequence selection: Choose unique regions within ATP6-1 mRNA to ensure specificity
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PPR protein design: Engineer the PPR protein to specifically recognize the target sequence based on the PPR code
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Subcellular targeting: Include appropriate mitochondrial targeting sequences to ensure the PPR protein reaches its intended location
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Expression level control: Use appropriate promoters to achieve desired knockdown levels without completely eliminating ATP6-1 expression
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Validation approaches: Employ qRT-PCR for mRNA levels, western blotting for protein levels, and functional assays (like ATP synthesis measurements) to confirm knockdown effectiveness
This approach has been successfully used to induce specific cleavage of ATP synthase subunit 1 (atp1) mRNA in mitochondria, resulting in approximately five-fold depletion of the protein while still allowing plants to grow, flower, and set seed .
