The full-length protein spans residues 1–77, with the sequence:
MIFLIISVPFGIYSLVIYNLTRRAPGKMRYLIPPLLTATLPALYLPLTGFKVSYDLLPVVGYLTYSQFLLLLLQLQR
.
Thermostability: Reflects the organism’s optimal growth at 83°C .
Purification: His-tag enables affinity chromatography for high-yield isolation .
Host Organism: A. fulgidus is a sulfate-reducing archaeon with a 2.3 Mbp genome, including genes for sulfate metabolism and CRISPR elements .
Protein Role: AF_1578’s function remains unknown, but its presence in A. fulgidus suggests potential involvement in:
While unrelated to AF_1578, A. fulgidus has been studied for DNA repair mechanisms, such as uracil-DNA glycosylase (UDG) activity in base excision repair (BER) . These studies highlight the organism’s unique biochemical adaptations, though AF_1578’s specific role in such pathways is unexplored.
Commercial Sources: Offered as lyophilized powder (e.g., Creative BioMart, CUSABIO) .
ELISA Kits: Available for antigen detection in research settings .
Functional Characterization: No direct evidence links AF_1578 to enzymatic activity, regulatory processes, or structural roles.
Interactome Studies: No reported interactions with other proteins or metabolites .
Hypothesis Testing: Potential targets include heat shock response, redox regulation, or sulfate metabolism, informed by A. fulgidus’ genomic inventory .
KEGG: afu:AF_1578
STRING: 224325.AF1578
Archaeoglobus fulgidus is a hyperthermophilic, sulfate-reducing archaeon commonly found in high-temperature and high-pressure marine environments, including deep-sea hydrothermal vents at depths of 2-5 km below sea level (20-50 MPa pressures) . It was the first hyperthermophilic sulfate-reducing archaeon to be isolated and characterized, and one of the first archaea to have its genome sequenced . AF_1578 is an uncharacterized protein from this organism, making it potentially valuable for understanding archaeal protein function in extreme environments.
Archaeoglobus fulgidus exhibits growth capabilities under various conditions. For heterotrophic metabolism (lactate oxidation coupled to sulfate reduction), it can grow at pressures up to 60 MPa, with maximum growth rates observed at 20 MPa, suggesting it is a moderate piezophile under these conditions . For autotrophic metabolism (CO₂ fixation coupled to thiosulfate reduction via H₂), it shows piezotolerance with growth rates remaining nearly constant from 0.3 to 40 MPa . The optimal temperature for growth is 83°C, making it a true hyperthermophile . These conditions are important to consider when studying native protein expression and function.
Based on available information, E. coli has been successfully used as an expression host for recombinant AF_1578 protein production . The protein has been produced with a His-tag, which facilitates purification through affinity chromatography techniques . When expressing archaeal proteins in bacterial systems, researchers should consider potential issues with protein folding, post-translational modifications, and stability at mesophilic temperatures. Alternative expression systems such as archaeal hosts might be considered for proteins that prove difficult to express functionally in bacterial systems.
AF_1578 is a relatively small protein with a length of 77 amino acids in its full-length form . While detailed structural information is not provided in the search results, its small size suggests it might function as part of a larger complex or have a specialized regulatory role. Computational prediction of secondary and tertiary structure would be valuable first steps in characterizing this protein.
Archaeoglobus fulgidus demonstrates remarkable piezotolerance and even piezophilic characteristics in some metabolic modes . For proteins from such organisms, pressure adaptation often involves structural modifications that maintain protein function under compression. These adaptations may include:
Increased hydrophobic core packing
Reduced void volumes within the protein structure
Strengthened ionic interactions
Modified amino acid composition favoring residues less affected by pressure
Experimental approaches to study pressure effects on AF_1578 should include:
High-pressure circular dichroism to assess secondary structure stability
Pressure-resolved fluorescence spectroscopy to monitor tertiary structure changes
Activity assays performed under pressure to correlate structural changes with function
Comparative analysis with homologous proteins from non-piezophilic organisms
For uncharacterized proteins like AF_1578, a multi-faceted bioinformatic approach is recommended:
Sequence homology searches against characterized proteins using sensitive methods like PSI-BLAST and HMM-based tools
Structural prediction using AlphaFold2 or similar tools, followed by structural homology searches
Genomic context analysis examining neighboring genes and potential operonic organization
Phylogenetic profiling to identify co-occurrence patterns with other proteins across species
Analysis of conserved domains and motifs that might suggest biochemical function
Computational prediction of protein-protein interaction partners
This comprehensive approach can generate testable hypotheses about AF_1578 function that can guide experimental design.
Given that Archaeoglobus fulgidus has a well-characterized heat shock response involving approximately 350 genes (14% of its genome) , investigating whether AF_1578 plays a role in this response would be valuable. A methodological approach should include:
Transcriptomic analysis: Compare AF_1578 expression levels before and after heat shock at different time points (similar to the study described for AF1298)
Promoter analysis: Examine the upstream region of AF_1578 for potential heat shock regulatory elements similar to the CTAAC-N5-GTTAG motif identified for HSR1-regulated genes
Protein-DNA interaction assays: Use electrophoretic mobility shift assays (EMSA) and DNase I footprinting to test if known heat shock regulators like HSR1 bind to the AF_1578 promoter region
Gene knockout or knockdown: Assess how loss of AF_1578 affects the organism's ability to survive heat shock
Interactome studies: Identify proteins that physically interact with AF_1578 under normal and heat shock conditions
The search results describe HSR1 (AF1298) as a heat shock regulator with DNA-binding capabilities . To investigate whether AF_1578 might have similar properties:
Sequence and structural analysis: Look for DNA-binding motifs such as helix-turn-helix domains similar to those found in HSR1
Electrophoretic mobility shift assays (EMSA): Test purified recombinant AF_1578 for binding to various DNA fragments, starting with its own promoter region (to test for autoregulation) and promoters of heat shock genes
DNase I footprinting: If binding is observed, determine the specific DNA sequence recognized by AF_1578
Chromatin immunoprecipitation: In vivo identification of genomic binding sites
Mutational analysis: Create point mutations in potential DNA-binding regions to confirm their importance
Studying protein-protein interactions (PPIs) for proteins from extremophiles presents unique challenges due to the extreme conditions required for native folding and function. For AF_1578, consider these approaches:
High-temperature pull-down assays: Adapt conventional pull-down methods to function at elevated temperatures
Chemical cross-linking mass spectrometry (XL-MS): Perform in vivo crosslinking at high temperatures before cell lysis to capture native interactions
Yeast two-hybrid adaptations: Use thermostable variants of the system or shuttle to archaeal two-hybrid systems
Surface plasmon resonance (SPR) under extreme conditions: Modified instruments that can operate at high temperatures
Hydrogen-deuterium exchange mass spectrometry (HDX-MS) to identify interaction interfaces
Reconstituted systems with purified components tested under various temperature and pressure conditions
These methods should be coupled with bioinformatic predictions of potential interaction partners based on genomic context and co-expression data.
For the purification of recombinant His-tagged AF_1578 expressed in E. coli , the following methodological approach is recommended:
Initial capture: Immobilized metal affinity chromatography (IMAC) using Ni-NTA or similar resin
Heat treatment: Exploiting the thermostability of archaeal proteins to remove mesophilic host contaminants by heating the lysate to 60-70°C
Secondary purification: Size exclusion chromatography to remove aggregates and ensure homogeneity
Quality control: Assess purity by SDS-PAGE and protein identity by mass spectrometry
Functional verification: Develop activity assays based on bioinformatic predictions of function
For researchers requiring protein for structural studies, additional considerations include buffer optimization to enhance stability and reduce aggregation.
Given that Archaeoglobus fulgidus is both thermophilic and piezotolerant/piezophilic , experiments studying AF_1578 should account for these environmental factors:
Temperature-dependent studies:
Thermal stability assays using differential scanning calorimetry or thermofluor assays
Activity measurements across a temperature range (60-90°C)
Structural characterization at different temperatures using circular dichroism or FTIR
Pressure-dependent studies:
Combined temperature-pressure experiments:
Establish a two-dimensional stability/activity map across relevant temperature and pressure ranges
Design specialized equipment that can maintain both high temperature and high pressure simultaneously
Since AF_1578 is uncharacterized, identifying its substrates or binding partners will be crucial for understanding its function. Consider these methodological approaches:
Metabolite profiling: Compare metabolomes of wild-type and AF_1578 knockout strains
Affinity purification: Use immobilized AF_1578 to capture interacting proteins or small molecules from cell lysates
Thermal proteome profiling: Identify proteins whose thermal stability changes upon binding to AF_1578
Library screening: Test interaction with libraries of metabolites, peptides, or nucleic acids
In silico docking: Computational prediction of potential binding partners based on structural models
Co-localization studies: If antibodies are available, use immunofluorescence to identify cellular localization that might suggest function
Expression of archaeal proteins in mesophilic hosts like E. coli often presents challenges due to differences in genetic code usage, folding environments, and post-translational modifications. To overcome these issues:
Codon optimization: Adjust codon usage to match the expression host
Fusion partners: Use solubility-enhancing fusion tags such as SUMO, MBP, or TrxA
Co-expression with chaperones: Include molecular chaperones from the native organism or thermostable chaperones
Expression conditions: Lower temperatures, slower induction, and specialized media formulations
Alternative hosts: Consider archaeal expression systems for particularly challenging proteins
Cell-free systems: Use thermostable cell-free expression systems derived from thermophiles
For AF_1578 specifically, expression in E. coli with a His-tag has been successful , suggesting that basic optimization strategies may be sufficient.
For a small protein like AF_1578 (77 amino acids) , appropriate structural characterization techniques include:
X-ray crystallography: If the protein can be crystallized, this offers high-resolution structural information
NMR spectroscopy: Particularly suitable for small proteins, providing both structural and dynamic information
Cryo-electron microscopy: Especially useful if AF_1578 forms larger complexes
Small-angle X-ray scattering (SAXS): For low-resolution shape determination in solution
Analytical ultracentrifugation: To determine oligomeric state and homogeneity
Native mass spectrometry: For accurate mass determination of intact complexes
Hydrogen-deuterium exchange mass spectrometry: To probe solvent accessibility and conformational dynamics
The small size of AF_1578 makes it an excellent candidate for NMR studies, which could provide detailed structural information even in the absence of crystallization.
Systems biology approaches can provide a holistic understanding of AF_1578's role:
Multi-omics integration: Combine transcriptomics, proteomics, and metabolomics data under various stress conditions
Network analysis: Place AF_1578 in the context of global protein-protein interaction networks
Comparative genomics: Analyze the conservation and evolution of AF_1578 across related extremophiles
Flux balance analysis: Model the metabolic impact of AF_1578 perturbation
Adaptive laboratory evolution: Select for strains with altered expression of AF_1578 and characterize adaptive mutations
This integrated approach could reveal emergent properties not apparent from isolated studies and place AF_1578 in the broader context of archaeal adaptation to extreme environments.
While avoiding commercial aspects as requested, the scientific exploration of potential applications includes:
Thermostable enzymes for research applications: If AF_1578 has enzymatic activity, its thermostability could be advantageous for high-temperature reactions
Structural biology insights: Understanding how small proteins from extremophiles maintain stability could inform protein engineering efforts
Biomarkers for environmental monitoring: If AF_1578 is specific to Archaeoglobus fulgidus, it could serve as a biomarker for detecting these organisms in environmental samples
Model systems for astrobiology: Extremophile proteins serve as models for potential extraterrestrial life
These applications represent scientific research directions rather than commercial developments.