Recombinant Archaeoglobus fulgidus Uncharacterized protein AF_1335 (AF_1335)

What is Archaeoglobus fulgidus AF_1335 protein?

AF_1335 is a full-length uncharacterized protein from the hyperthermophilic archaeon Archaeoglobus fulgidus. It consists of 156 amino acids with the sequence: MVSRTTTSIPINFRGVGVYKTFANKNLLYCNCNIVSMEKTDLLMMTFAIVNLADYMTTVKGIEMGFHELNEFVSSLNPASFLLLKIAIVATAFALLLYTRRLSFSLGRGIYIGLVAGLAISTAVLGICSVHNLLLLTGFPEVEFLVKVMTGVLALI . The protein has been recombinantly expressed with an N-terminal His-tag in E. coli expression systems for research purposes . As an uncharacterized protein, its precise biological function remains to be elucidated through structural and functional studies.

How should Recombinant AF_1335 protein be stored and reconstituted for experimental use?

For optimal stability, store Recombinant AF_1335 protein at -20°C to -80°C upon receipt, with aliquoting recommended to avoid repeated freeze-thaw cycles that may compromise protein integrity . Working aliquots may be maintained at 4°C for up to one week .

For reconstitution:

• Briefly centrifuge the vial before opening to ensure collection of all material

• Reconstitute in deionized sterile water to a concentration of 0.1-1.0 mg/mL

• Add glycerol to a final concentration of 5-50% (50% is standard) for long-term storage

• Store reconstituted protein in aliquots at -20°C/-80°C

The protein is typically supplied in a Tris/PBS-based buffer containing 6% Trehalose at pH 8.0, which helps maintain stability during lyophilization and storage .

What methodological approaches should be used to functionally annotate AF_1335?

Functional annotation of uncharacterized proteins like AF_1335 requires a multi-faceted computational and experimental approach:

• Sequence-Based Analysis:

  • Perform homology searches using BLASTP against non-redundant protein databases

  • Apply Position-Specific Iterative BLAST (PSI-BLAST) for detecting remote homologs

  • Conduct multiple sequence alignments with related proteins

• Structural Prediction and Analysis:

  • Generate 3D models using homology modeling (Swiss-Model) or ab initio modeling (Phyre2)

  • Identify structural motifs that might suggest function

  • Conduct molecular dynamics simulations to understand protein behavior

• Domain Identification:

  • Utilize multiple domain databases including InterProScan, SMART, and HMMER

  • Apply consensus approach by considering domains predicted by at least two different tools

  • Analyze conserved motifs using Motif and NCBI CDART searches

• Experimental Validation:

  • Design targeted biochemical assays based on predicted functions

  • Conduct protein-protein interaction studies (pull-down assays, yeast two-hybrid)

  • Perform genetic studies (gene knockouts, complementation tests)

This integrated approach has demonstrated success in annotating previously uncharacterized proteins with an average accuracy of 83% based on ROC analysis .

How can computational tools help predict the cellular localization and function of AF_1335?

Predicting the cellular localization and function of AF_1335 requires implementing multiple computational tools with cross-validation:

• Physicochemical Property Analysis:

  • Calculate molecular weight, isoelectric point, and hydropathicity using ProtParam

  • Analyze GRAVY (Grand Average of Hydropathicity) values to determine hydrophilic/hydrophobic nature

  • Assess instability index to predict protein stability (values <40 indicate stable proteins)

• Transmembrane Region Prediction:

  • Analyze the AF_1335 sequence using TMHMM, HMMTOP, or Phobius

  • Identify potential membrane-spanning regions based on hydrophobicity patterns

  • The sequence "AIVATAFALLLYTRRLSFSLGRGIYIGLVAGLAISTAVLGICSVHNLLLLTGFPEVEFLVKVMTGVLALI" contains hydrophobic stretches that may indicate transmembrane domains

• Subcellular Localization Tools:

  • Apply PSORT, TargetP, and CELLO for archaeal proteins

  • Compare predictions across multiple tools to increase confidence

• Function Prediction Pipeline:

  • Implement protein-protein interaction analysis using STRING database

  • Conduct gene neighborhood and co-expression analyses

  • Perform functional domain analysis and correlate with protein structure predictions

For AF_1335, integrating these predictions with the archaeal subcellular organization context is crucial, as standard bacterial or eukaryotic localization signals may not apply to this extremophile species.

What experimental design would best elucidate the function of AF_1335?

An optimal experimental design for elucidating AF_1335 function should incorporate both in vitro and in vivo approaches with appropriate controls:

• Experimental Design Framework:

  • Implement a classical experimental design with control and treatment groups

  • Ensure both causal propositions are addressed: "If X, then Y" and "If not X, then not Y"

  • Incorporate negative controls (vector-only expression) and positive controls (expression of proteins with known function)

• Genetic Manipulation Studies:

  • Generate AF_1335 knockout strains in A. fulgidus (if genetic systems are available)

  • Create conditional expression systems to control protein levels

  • Perform complementation studies with predicted functional homologs

• Protein Interaction Network Analysis:

  • Conduct pull-down assays using His-tagged AF_1335

  • Perform crosslinking studies followed by mass spectrometry

  • Use yeast two-hybrid or bacterial two-hybrid systems to identify interaction partners

• Biochemical Activity Assays:

  • Test predicted enzymatic activities based on structural or sequence homology

  • Assess binding to various substrates and cofactors

  • Evaluate activity under different conditions (temperature, pH, salt concentration) relevant to A. fulgidus

• Structural Studies:

  • Perform X-ray crystallography or cryo-EM to determine 3D structure

  • Conduct NMR for dynamic structural information

  • Use circular dichroism to assess secondary structure elements

This multi-faceted experimental design addresses the causality requirements for rigorous research while providing multiple lines of evidence for functional characterization.

How should researchers design structure-function studies for AF_1335?

A systematic structure-function analysis of AF_1335 requires strategic experimental planning:

• Initial Structural Assessment:

  • Generate high-resolution structures through X-ray crystallography or cryo-EM

  • Perform structural alignments with characterized proteins to identify functional motifs

  • Analyze potential binding pockets or active sites using computational tools

• Site-Directed Mutagenesis Strategy:

  • Design a targeted mutagenesis matrix focusing on:

    • Conserved residues identified through multiple sequence alignments

    • Amino acids in predicted active sites or binding pockets

    • Residues at protein-protein interaction interfaces

  • Include both conservative and non-conservative mutations to assess functional importance

• Functional Assay Design:

  • Develop activity assays based on predicted functions

  • Measure binding affinity changes using techniques like isothermal titration calorimetry

  • Evaluate structural stability of mutants through thermal shift assays

• Structure-Activity Relationship Analysis:

  • Correlate structural changes with functional impacts

  • Map mutation effects onto the 3D structure

  • Generate structure-based models of protein mechanism

• Validation in Cellular Context:

  • Express wild-type and mutant proteins in heterologous systems

  • Evaluate phenotypic changes in complementation studies

  • Assess interaction changes through in vivo assays

This systematic approach provides a comprehensive understanding of how specific structural elements contribute to AF_1335 function, creating a foundation for targeted applications in biotechnology or structural biology.

How can AF_1335 be leveraged for extremozyme biotechnology applications?

Archaeoglobus fulgidus AF_1335 presents significant potential for extremozyme biotechnology due to its origin from a hyperthermophilic archaeon that thrives in extreme environments:

• Thermostability Assessment:

  • Conduct thermal stability assays to determine temperature optima and denaturation profiles

  • Measure enzymatic activity (if identified) across temperature ranges (25-100°C)

  • Compare stability with mesophilic homologs to identify thermostabilizing features

• Engineering Enhanced Properties:

  • Apply directed evolution techniques to optimize activity under specific conditions

  • Perform rational design modifications based on structural insights

  • Create chimeric proteins by combining thermostable domains with functional domains from other proteins

• Industrial Application Testing:

  • Evaluate performance in relevant industrial processes that require thermostable enzymes

  • Assess compatibility with organic solvents and other denaturing conditions

  • Determine long-term stability under process conditions

• Immobilization Strategies:

  • Leverage the His-tag for oriented immobilization on metal affinity surfaces

  • Develop cross-linking methodologies for enzyme stabilization

  • Optimize immobilization matrices for specific applications

• Scale-Up Considerations:

  • Develop optimized expression systems for high-yield production

  • Establish purification protocols compatible with industrial-scale processes

  • Validate activity retention during scale-up procedures

The recombinant production of AF_1335 in E. coli already demonstrates its amenability to heterologous expression systems , an essential feature for biotechnological applications.

What approaches should be used to study potential protein-protein interactions of AF_1335?

Investigating protein-protein interactions (PPIs) for AF_1335 requires a combination of computational predictions and experimental validations:

• Computational Prediction Methods:

  • Apply homology-based interaction prediction tools

  • Conduct docking simulations with potential partners

  • Perform co-evolution analysis to identify potential interacting partners

• Affinity-Based Experimental Methods:

  • Utilize His-tagged AF_1335 for pull-down assays with A. fulgidus lysates

  • Perform co-immunoprecipitation with antibodies against AF_1335

  • Implement BioID or proximity labeling approaches for identifying transient interactions

• Biophysical Interaction Analysis:

  • Conduct surface plasmon resonance (SPR) with purified potential partners

  • Perform isothermal titration calorimetry (ITC) for thermodynamic parameters

  • Use microscale thermophoresis (MST) for interaction studies under native-like conditions

• Structural Studies of Complexes:

  • Obtain crystal structures of AF_1335 with binding partners

  • Use cryo-EM for larger complexes

  • Perform hydrogen-deuterium exchange mass spectrometry to map interaction interfaces

• In Vivo Validation Approaches:

  • Implement bimolecular fluorescence complementation (BiFC) in heterologous systems

  • Use protein-fragment complementation assays

  • Perform co-localization studies with fluorescently tagged proteins

These approaches should be integrated with the functional annotation efforts, as interaction partners often provide crucial clues about protein function, particularly for uncharacterized proteins.

How does AF_1335 relate evolutionarily to characterized proteins in other organisms?

Understanding the evolutionary context of AF_1335 requires a systematic comparative analysis:

• Phylogenetic Analysis Methodology:

  • Conduct sensitive homology searches using PSI-BLAST and HHpred

  • Build multiple sequence alignments of homologs across archaea, bacteria, and eukarya

  • Construct phylogenetic trees using maximum likelihood or Bayesian methods

  • Calculate evolutionary rates to identify conserved regions under selective pressure

• Domain Architecture Analysis:

  • Compare domain organization with homologs using tools like InterProScan

  • Identify domain shuffling events or fusions that might indicate functional adaptation

  • Assess conservation of specific motifs across evolutionary distance

• Genomic Context Examination:

  • Analyze gene neighborhoods in Archaeoglobus fulgidus and related species

  • Identify co-evolved gene clusters that might indicate functional relationships

  • Assess horizontal gene transfer events that might have contributed to AF_1335 evolution

• Structural Homology Assessment:

  • Conduct structural alignments with solved structures of homologs

  • Identify structurally conserved regions that may indicate functional sites

  • Analyze evolutionary conservation mapped onto 3D structures

• Adaptation Signature Analysis:

  • Evaluate amino acid composition in context of thermophilic adaptation

  • Identify unique features that distinguish AF_1335 from mesophilic homologs

  • Assess potential evolutionary adaptation to the sulfate-reducing lifestyle of A. fulgidus

This evolutionary context provides critical insights into potential functions and the selective pressures that have shaped AF_1335 throughout evolutionary history.

What methodological approaches should be used to study AF_1335 under extremophilic conditions?

Investigating AF_1335 under extremophilic conditions requires specialized methodological considerations:

• High-Temperature Biochemistry Techniques:

  • Implement assay systems functional at 70-85°C (A. fulgidus growth optimum)

  • Use thermostable buffers and reagents that maintain pH at elevated temperatures

  • Employ specialized equipment for high-temperature activity measurements

• Structural Stability Analysis Protocol:

  • Conduct differential scanning calorimetry (DSC) to determine thermal transitions

  • Perform circular dichroism (CD) spectroscopy at increasing temperatures

  • Use intrinsic fluorescence to monitor unfolding under various conditions

• Functional Assays Under Extremophilic Conditions:

  • Design assays compatible with anaerobic, high-temperature, and potentially high-pressure conditions

  • Include appropriate controls using known thermostable proteins

  • Adapt standard enzymatic assays for high-temperature compatibility

• In Vitro Reconstitution Systems:

  • Develop experimental systems that mimic the native cytoplasmic environment of A. fulgidus

  • Adjust salt concentrations and pH to match physiological conditions

  • Include potential cofactors and interaction partners from A. fulgidus

• Comparative Performance Assessment:

  • Systematically evaluate protein behavior across temperature ranges (25-95°C)

  • Compare activity in the presence of varying salt concentrations

  • Assess stability under different redox conditions relevant to A. fulgidus metabolism

These specialized approaches ensure that functional studies are conducted under conditions that reflect the native environment of AF_1335, providing more physiologically relevant insights into its biological role.