Recombinant Trichophyton verrucosum Altered inheritance of mitochondria protein 31, mitochondrial (AIM31)

What is Trichophyton verrucosum AIM31 protein?

AIM31 (Altered inheritance of mitochondria protein 31) is a mitochondrial protein found in Trichophyton verrucosum, a dermatophyte fungus known to cause skin infections in animals and humans. The protein is encoded by the AIM31 gene (also known as TRV_05213 in T. verrucosum strain HKI 0517) and consists of 189 amino acids in its full-length form . The mature protein has a molecular structure that includes mitochondrial targeting sequences and functional domains associated with mitochondrial membrane organization.

The protein sequence of T. verrucosum AIM31 is: MSDKPLPSSFDDDPDFFQDNAWKKLGRRLKEEPLVPLGIGATCYALFRAYRSMKMGDSVQVNRMFRARIYAQAFTLLAVCAGSVYYKTERDQRKQLEKAMDLKKQQAKRDAWLKELEIRQEDKDWQSRHATIEQAAKGVEVKPFVADSAPDAAGRDASEEPAKESGDKKDGGSGGVLSAVKNLSWGSK . This protein has homologs in other fungal species, including Ajellomyces capsulata where it's also designated as AIM31, suggesting evolutionary conservation of this mitochondrial protein across fungal taxa .

What is the taxonomic context of Trichophyton verrucosum?

Trichophyton verrucosum belongs to the Trichophyton benhamiae complex, which encompasses nine related taxa that are primarily animal pathogens with zoonotic potential . Within the broader context of dermatophytes:

• T. verrucosum is historically recognized as a well-known agent of dermatophytosis in cattle and a cause of zoonotic infections, particularly in agricultural workers .

• The species is part of a group of dermatophytes that includes T. rubrum (the major cause of athlete's foot), T. equinum, T. tonsurans, and several other clinically relevant species .

• While T. verrucosum infections have decreased in Europe due to improved agricultural procedures and cattle vaccination, they remain significant in many regions worldwide .

• The organism belongs to a larger group of dermatophyte fungi characterized by specific genomic features, including expanded families of proteases, kinases, secondary metabolism genes, and LysM domain-containing proteins .

How is recombinant T. verrucosum AIM31 typically produced for research?

Recombinant T. verrucosum AIM31 protein can be produced using several expression systems, each with specific advantages for different research applications. The methodological approach typically involves:

• Gene cloning: The AIM31 gene sequence from T. verrucosum is amplified and cloned into an appropriate expression vector with a selected tag system for purification and detection purposes .

• Expression system selection: Common expression systems include:

  • E. coli-based expression for high yield and cost-effectiveness

  • Yeast-based expression for eukaryotic post-translational modifications

  • Baculovirus-infected insect cells for more complex eukaryotic processing

  • Mammalian cells for highest fidelity to native eukaryotic protein folding

• Purification strategy: Typically involves affinity chromatography based on the fusion tag selected during vector design. Common tags include His-tags, GST, or specialized biotinylation tags like Avi-tag for specific applications .

• Quality control: Verification of protein identity and purity using SDS-PAGE, mass spectrometry, and functional assays to ensure biological activity is preserved.

The recombinant protein is often stored in a Tris-based buffer with 50% glycerol to maintain stability, and researchers are advised to avoid repeated freeze-thaw cycles by storing working aliquots at 4°C for short-term use .

What is the proposed function of AIM31 in fungal mitochondria?

The AIM31 protein in fungi, including T. verrucosum, is implicated in several critical mitochondrial functions, although research specifically on T. verrucosum AIM31 is limited. Based on studies of homologous proteins in related fungi:

• Mitochondrial inheritance: As suggested by its name (Altered inheritance of mitochondria), AIM31 appears to play a role in the proper distribution and inheritance of mitochondria during cell division .

• Respiratory chain function: In some fungi, AIM31 is also known as RCF1 (Respiratory supercomplex factor 1), suggesting involvement in the organization and function of respiratory chain complexes in the mitochondrial inner membrane .

• Mitochondrial membrane organization: The protein likely contributes to the structural integrity and organization of mitochondrial membranes, which is essential for proper organelle function and energy production.

• Potential role in pathogenicity: Given that mitochondrial function is critical for fungal viability and virulence, AIM31 may indirectly contribute to the pathogenic potential of T. verrucosum, though direct evidence for this connection requires further investigation.

Comparative genomic analyses of dermatophytes, including T. verrucosum, have revealed that these fungi contain expanded families of genes related to secondary metabolism, kinases, proteases, and LysM binding domains, which collectively contribute to their pathogenic lifestyle .

How does the structure of T. verrucosum AIM31 relate to its function?

While the detailed three-dimensional structure of T. verrucosum AIM31 has not been fully characterized in the available literature, several structural features can be inferred from sequence analysis and comparison with homologous proteins:

• Mitochondrial targeting sequence: The N-terminal portion of the protein likely contains signals that direct the protein to the mitochondria after synthesis in the cytoplasm.

• Transmembrane domains: Analysis of the amino acid sequence (MSDKPLPSSFDDDPDFFQDNAWKKLGRRLKEEPLVPLGIGATCYALFRAYRSMKMGDSVQVNRMFRARIYAQAFTLLAVCAGSVYYKTERDQRKQLEKAMDLKKQQAKRDAWLKELEIRQEDKDWQSRHATIEQAAKGVEVKPFVADSAPDAAGRDASEEPAKESGDKKDGGSGGVLSAVKNLSWGSK) suggests the presence of hydrophobic regions that could span the mitochondrial membrane .

• Functional domains: The protein likely contains domains that mediate interactions with other mitochondrial proteins, particularly those involved in respiratory chain complexes.

• Conservation patterns: Comparative analysis of AIM31 across multiple fungal species could reveal highly conserved regions that are essential for function, though this specific analysis is not presented in the available search results.

Understanding the structure-function relationship of T. verrucosum AIM31 would benefit from techniques such as X-ray crystallography, NMR spectroscopy, or cryo-electron microscopy to resolve its three-dimensional structure.

What are the optimal conditions for expressing recombinant T. verrucosum AIM31?

When designing expression systems for recombinant T. verrucosum AIM31, researchers should consider the following parameters for optimal results:

• Expression vector selection:

  • For prokaryotic expression: pET series vectors with T7 promoter systems offer strong inducible expression in E. coli

  • For eukaryotic expression: Vectors with appropriate promoters for yeast, insect, or mammalian cell expression systems

• Expression host considerations:

  • E. coli: Simple and cost-effective, but lacks eukaryotic post-translational machinery

  • Yeast: Provides eukaryotic processing with relatively high yield

  • Insect cells: Better for complex eukaryotic proteins

  • Mammalian cells: Highest fidelity but lower yield and higher cost

• Optimization parameters:

  • Induction conditions: Temperature, inducer concentration, and timing

  • Growth media composition: Nutrient availability and buffering capacity

  • Harvest timing: Balancing protein yield with solubility

• Fusion tag selection:

  • His-tag: Simple purification via nickel affinity

  • Avi-tag biotinylation: For applications requiring high-affinity biotin-streptavidin interaction

  • GST-tag: Can enhance solubility of the recombinant protein

• Codon optimization:

  • Adapting the T. verrucosum gene sequence to the codon usage bias of the expression host can significantly improve expression levels

Experimental designs should include appropriate controls and optimization steps to ensure the recombinant protein maintains its native structure and function.

What analytical methods are most effective for studying AIM31 interactions with other mitochondrial proteins?

Several analytical approaches can be employed to study AIM31 interactions with other mitochondrial proteins, each offering different insights:

• Co-immunoprecipitation (Co-IP):

  • Using antibodies against tagged recombinant AIM31 to pull down interacting proteins

  • Mass spectrometry analysis of co-precipitated proteins to identify interaction partners

  • Verification with reciprocal Co-IP using antibodies against identified partners

• Yeast two-hybrid screening:

  • Using AIM31 as bait to screen for interacting proteins from a cDNA library

  • Validation of positive interactions through secondary assays

• Proximity-based labeling:

  • BioID or APEX2 fusion with AIM31 to biotinylate proximal proteins in the mitochondrial environment

  • Streptavidin-based purification followed by mass spectrometry identification

• Fluorescence microscopy techniques:

  • Förster Resonance Energy Transfer (FRET) to detect protein-protein interactions in living cells

  • Bimolecular Fluorescence Complementation (BiFC) to visualize interaction partners

• Surface Plasmon Resonance (SPR):

  • Quantitative analysis of binding kinetics between purified AIM31 and potential interacting partners

  • Determination of binding affinities and association/dissociation rates

• Isothermal Titration Calorimetry (ITC):

  • Direct measurement of thermodynamic parameters of protein-protein interactions

  • Provides information on binding stoichiometry and energetics

These methods can be particularly valuable given that comparative genomic analyses of dermatophytes have revealed significant expansion of specific functional categories, including kinases and proteases, which may interact with mitochondrial proteins like AIM31 in biological contexts .

What is the potential role of AIM31 in T. verrucosum pathogenicity?

While direct evidence linking AIM31 to T. verrucosum pathogenicity is not explicitly stated in the search results, we can infer potential connections based on the known functions of mitochondrial proteins and the pathogenic mechanisms of dermatophytes:

T. verrucosum is known to cause highly inflammatory infections in both animals and humans, as evidenced by clinical cases like those described in llamas and their breeder . Understanding the contribution of specific proteins like AIM31 to this inflammatory response could provide insights into the pathogenesis of these infections.

How does T. verrucosum transmission between animals and humans relate to protein expression patterns?

T. verrucosum exhibits significant zoonotic potential, with documented cases of transmission between animals and humans . The relationship between this transmission and protein expression patterns can be explored from several angles:

• Host adaptation mechanisms:

  • During cross-species transmission, T. verrucosum likely undergoes changes in gene expression, potentially including mitochondrial proteins like AIM31, to adapt to different host environments

  • Comparative proteomic analysis of T. verrucosum isolates from different host species could reveal adaptive changes in protein expression

• Epidemiological evidence:

  • Molecular analyses of T. verrucosum isolates from humans and animals show high genetic similarity, indicating direct transmission

  • PCR fingerprinting methods have demonstrated the identical source of infection in cases involving animals and their handlers

• Clinical presentation correlation:

  • T. verrucosum causes highly inflammatory tinea corporis in humans, particularly those in contact with infected animals

  • The protein expression profile, including mitochondrial proteins, may contribute to this inflammatory response

• Diagnostic applications:

  • Understanding differential protein expression patterns could lead to improved diagnostic methods

  • Molecular typing based on conserved genes can help track transmission chains in outbreak scenarios

As noted in epidemiological studies, farmers, veterinarians, and others handling infected animals are at higher risk of acquiring T. verrucosum infections , suggesting that direct contact is a primary transmission route. The role of specific proteins like AIM31 in this process remains an area for further investigation.

How can gene knockout or silencing of AIM31 inform our understanding of its function in T. verrucosum?

Gene knockout or silencing approaches offer powerful tools for elucidating AIM31 function in T. verrucosum. A comprehensive experimental approach would include:

• CRISPR-Cas9 gene editing:

  • Design of guide RNAs targeting the AIM31 locus

  • Generation of knockout strains through homology-directed repair

  • Phenotypic characterization of knockout mutants for growth, morphology, and pathogenicity

• RNA interference (RNAi):

  • Development of RNAi constructs targeting AIM31 transcripts

  • Transformation of T. verrucosum with RNAi constructs for conditional knockdown

  • Analysis of phenotypic changes under various conditions

The available literature indicates that RNAi mechanisms are present in dermatophytes, as homologs of Argonaut and dicer have been identified in these fungi, suggesting that RNAi gene knockdown approaches could be viable for functional analysis .

• Phenotypic assessment parameters:

  • Mitochondrial morphology and distribution

  • Respiratory chain function and ATP production

  • Growth rate and colony morphology

  • Stress response and adaptation

  • Virulence in appropriate infection models

• Complementation studies:

  • Reintroduction of the wild-type AIM31 gene to confirm phenotypic restoration

  • Introduction of AIM31 variants to identify critical functional domains

  • Cross-species complementation with AIM31 homologs from related fungi

• Multi-omics analysis:

  • Transcriptomic profiling to identify compensatory responses

  • Proteomic analysis to detect changes in protein-protein interaction networks

  • Metabolomic studies to characterize alterations in cellular metabolism

These approaches would help establish whether AIM31 is essential for viability in T. verrucosum and elucidate its specific roles in mitochondrial function and potentially in pathogenicity.

What comparative genomic insights can be gained by studying AIM31 across different Trichophyton species?

Comparative genomic analysis of AIM31 across multiple Trichophyton species can provide valuable insights into evolutionary conservation, functional importance, and potential species-specific adaptations:

• Sequence conservation analysis:

  • Alignment of AIM31 sequences from various Trichophyton species, including T. verrucosum, T. rubrum, T. equinum, T. tonsurans, and newly discovered species like T. persicum and T. spiraliforme

  • Identification of highly conserved regions suggesting functional importance

  • Detection of species-specific variations that might correlate with host range or pathogenicity

• Genomic context examination:

  • Analysis of the genomic neighborhood of AIM31 across species

  • Identification of conserved or species-specific gene clusters

  • Detection of horizontal gene transfer events or genomic rearrangements

• Evolutionary rate analysis:

  • Calculation of synonymous and non-synonymous substitution rates

  • Assessment of selective pressure acting on different regions of the protein

  • Correlation with species diversification and host adaptation

• Host-specificity correlations:

  • Comparison of AIM31 sequences from anthropophilic, zoophilic, and geophilic dermatophytes

  • Identification of sequence features that correlate with host preference

  • Analysis in the context of the expanded gene families observed in dermatophytes, including those related to secondary metabolism, kinases, proteases, and LysM binding domains

• Structural predictions:

  • Homology modeling of AIM31 from different species

  • Comparison of predicted structural features and potential functional sites

  • Correlation of structural differences with species-specific biological properties

This comparative approach would benefit from the expanding genomic resources for dermatophytes, including the complete genome sequences now available for multiple Trichophyton species .

What are the most promising therapeutic applications targeting AIM31 or related proteins?

While direct therapeutic targeting of AIM31 has not been extensively explored in the available literature, several promising research directions could emerge from understanding this protein:

• Antifungal drug development:

  • If AIM31 proves essential for T. verrucosum viability or virulence, it could represent a novel target for antifungal therapy

  • Structure-based drug design could identify compounds that selectively inhibit fungal AIM31 without affecting human mitochondrial proteins

  • Development of compounds disrupting protein-protein interactions involving AIM31 in the mitochondrial membrane

• Vaccine strategies:

  • Assessment of AIM31 as a potential vaccine antigen for preventing T. verrucosum infections in livestock

  • Evaluation of recombinant AIM31 in subunit vaccine formulations

  • This approach aligns with the successful vaccination strategies that have reduced T. verrucosum infections in cattle in many regions

• Diagnostic applications:

  • Development of AIM31-based serological assays for detecting T. verrucosum infections

  • Design of PCR or other molecular diagnostic tests targeting the AIM31 gene

  • Integration into multiplex assays that can differentiate between different dermatophyte species

• Broader antifungal approaches:

  • Targeting conserved features of fungal mitochondrial proteins like AIM31 across multiple dermatophyte species

  • Development of combination therapies targeting both cell wall/membrane and mitochondrial functions

  • Leveraging comparative genomic insights to identify conserved vulnerabilities in dermatophyte metabolism

• One Health applications:

  • Given the zoonotic nature of T. verrucosum infections , strategies targeting AIM31 could have applications in both veterinary and human medicine

  • Integrated approaches considering both animal reservoirs and human infections would be most effective

How might systems biology approaches enhance our understanding of AIM31 function in the context of fungal pathogenesis?

Systems biology offers powerful frameworks for understanding complex biological processes. For investigating AIM31 function in T. verrucosum pathogenesis, several systems approaches show promise:

• Multi-omics integration:

  • Combining transcriptomics, proteomics, and metabolomics data from wild-type and AIM31-modified strains

  • Integration of data collected under various conditions (in vitro growth, infection models, stress responses)

  • Construction of comprehensive interaction networks highlighting AIM31's position in cellular systems

• Computational modeling:

  • Development of mathematical models of mitochondrial function incorporating AIM31

  • Prediction of system-wide effects of AIM31 perturbation

  • Simulation of different infection scenarios to identify critical control points

• Host-pathogen interaction networks:

  • Mapping the dynamic interplay between T. verrucosum proteins (including AIM31) and host factors

  • Identification of critical nodes in the infection process

  • Analysis in the context of the expanded families of proteases, kinases, and other virulence factors in dermatophytes

• Comparative systems analysis:

  • Extending analysis across multiple dermatophyte species with different host preferences

  • Correlation of system-level differences with host range and virulence

  • Identification of conserved and species-specific system components

• Temporal dynamics analysis:

  • Characterization of time-resolved changes in AIM31 expression and interaction networks during infection

  • Mapping the sequence of events from initial host contact to established infection

  • Identification of critical transition points that could be targeted therapeutically

Such systems approaches would benefit from the expanding genomic and molecular data available for dermatophytes and could lead to more comprehensive understanding of the complex role of mitochondrial proteins like AIM31 in fungal pathogenesis.