Recombinant Lodderomyces elongisporus Formation of crista junctions protein 1 (FCJ1)
Description
Gene and Synonyms
The gene encoding FCJ1 is known as MIC60 (LELG_00268) in Lodderomyces elongisporus, reflecting its identity as a MICOS complex subunit . Common synonyms for this protein include:
These multiple designations reflect the protein's conserved function across different fungal species and its critical role in mitochondrial membrane organization.
Taxonomic Context and General Characteristics
Lodderomyces elongisporus is a diploid, ascomycetous yeast that has emerged as a significant opportunistic pathogen. This organism is frequently misidentified as Candida parapsilosis due to phenotypic similarities, though molecular analysis through D1/D2 sequence analysis can provide accurate identification . It has been isolated from diverse sources including soft drinks, juice concentrates, natural cocoa fermentations, soil, infected fingernails, human bloodstream infections, and baby cream .
Morphologically, L. elongisporus forms white to cream-colored colonies on Sabouraud Dextrose Agar (SDA) that appear smooth, glabrous, and yeast-like . Under microscopic examination, the organism displays ellipsoid to elongate budding blastoconidia measuring 2.6-6.3 × 4-7.4 μm, occasionally presenting spherical forms . A distinctive feature of this organism is its ability to form ascospores, with asci transformed from budding cells producing one, rarely two, long-ellipsoid ascospores, typically observable on V8 agar after 7-10 days of incubation at 25°C .
Clinical Significance and Antifungal Susceptibility
L. elongisporus has gained increased attention due to its emergence as a causative agent in fungemia outbreaks, particularly in neonatal intensive care units (NICUs) . The clinical strains of L. elongisporus typically exhibit susceptibility to multiple antifungal agents, as evidenced by the following minimum inhibitory concentration (MIC) data:
| L. elongisporus (no. of isolates) | MIC range (mg/L) | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| FLU | ITC | VRC | ISA | POS | AMB | MFG | AFG | 5-FC | |
| Clinical, bloodstream isolates (n = 13) | 0.25–1 | 0.03–0.25 | <0.03–0.06 | <0.015 | <0.015–0.125 | 0.125–0.5 | <0.015–0.125 | <0.015–0.5 | 0.06–0.25 |
| Inanimate environment, NICU (n = 2) | 0.5 | 0.03–0.06 | <0.03 | <0.015 | <0.015 | 0.25 | <0.015 | <0.015–0.5 | 0.06 |
| Inanimate environment of two hospitals (n = 3) | 0.5 | 0.03–0.06 | <0.03 | <0.015 | <0.015 | 0.25 | <0.015 | <0.015–0.5 | 0.06 |
Interestingly, strains isolated from the surfaces of stored apples displayed 2- to 8-fold higher fluconazole MICs (range: 2-4 mg/L) compared to clinical and environmental isolates, suggesting potential environmental adaptation mechanisms . Genomic analysis of these resistant strains revealed 119 nonsynonymous single nucleotide polymorphisms in 24 triazole resistance-related genes previously identified in other Candida species .
Role in Mitochondrial Structure
The Formation of crista junctions protein 1 (FCJ1) plays a critical role in the architecture of mitochondria, specifically in the formation and maintenance of crista junctions. These structures represent the narrow tubular connections between the inner boundary membrane and the cristae membranes of mitochondria, which are essential for proper mitochondrial function and energetics. As a component of the MICOS complex (Mitochondrial Contact Site and Cristae Organizing System), FCJ1/MIC60 participates in the organization of mitochondrial inner membrane structure.
The function of FCJ1 in L. elongisporus appears to be conserved with homologous proteins in other fungi, reflecting its essential role in mitochondrial biology across diverse species. The protein's involvement in fundamental cellular processes suggests it may play indirect roles in pathogenicity, stress resistance, and metabolic adaptation of L. elongisporus in various environments.
Potential Research Applications
The availability of recombinant FCJ1 from L. elongisporus enables various research applications in fungal biology and pathogenesis. These may include:
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Studies of mitochondrial dynamics in pathogenic fungi
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Comparative analysis of mitochondrial architecture across Candida and related species
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Investigation of mitochondrial function in antifungal resistance mechanisms
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Development of targeted therapies disrupting mitochondrial function in pathogenic yeasts
Genetic Diversity and Strain Variations
Genomic analyses of L. elongisporus isolates have revealed significant diversity and evidence of recombination. Clinical and environmental isolates typically cluster together genetically, while strains from other sources such as fruit surfaces may show considerable genomic divergence . This genetic diversity may influence the expression and function of proteins like FCJ1 across different strains.
Product Specs
Please note: We prioritize shipping the format currently in stock. However, if you have a specific format requirement, please indicate it when placing your order. We will fulfill your request if possible.
Note: All of our proteins are shipped with standard blue ice packs. If you require dry ice shipping, please inform us in advance as additional fees will apply.
Generally, the shelf life of liquid form is 6 months at -20°C/-80°C. The shelf life of lyophilized form is 12 months at -20°C/-80°C.
Target Background
KEGG: lel:LELG_00268
STRING: 379508.XP_001527748.1
Q&A
What is the taxonomic classification of Lodderomyces elongisporus and how does it relate to the Candida clade?
Lodderomyces elongisporus is a diploid ascomycete yeast originally described as Saccharomyces elongisporus in 1952. Phylogenetic analyses based on DNA sequences (single gene, multiple genes, and whole genomes) have definitively clustered L. elongisporus within the Candida clade, with particularly close relation to the Candida parapsilosis species complex (including C. parapsilosis, C. orthopsilosis, and C. metapsilosis) . The genome size of L. elongisporus (15-16 Mb) is slightly larger than that of C. parapsilosis (12-13 Mb) but comparable to other pathogenic Candida species such as C. albicans (14-16 Mb) . Like other members of the CTG clade, L. elongisporus translates the CUG codon to serine instead of leucine, a distinctive genetic characteristic that defines this phylogenetic group .
What are the morphological and cultural characteristics that distinguish L. elongisporus from similar species?
L. elongisporus produces white to cream-colored, smooth, glabrous, yeast-like colonies on Sabouraud dextrose agar that strongly resemble C. parapsilosis colonies . Microscopically, it forms ellipsoid to elongate budding blastoconidia measuring 2.6-6.3 × 4-7.4 μm, occasionally with spherical forms . The species produces abundant, much-branched pseudohyphae in Dalmau plate cultures .
A key differential characteristic is that L. elongisporus forms turquoise blue colonies on CHROMagar, distinct from the white to pale pink colonies typical of C. parapsilosis . This chromogenic differentiation provides an important clue for distinguishing these closely related species in clinical laboratory settings .
What is the global distribution and clinical prevalence of L. elongisporus infections?
Since its first recognition as a human pathogen in 2008, L. elongisporus infections have been reported in 14 countries across 5 continents . The species has been increasingly isolated from various clinical specimens, particularly blood cultures. Its actual prevalence may be significantly underestimated due to frequent misidentification as C. parapsilosis using conventional biochemical methods .
Hospital environments appear to serve as reservoirs for L. elongisporus, with documented cases of transmission within healthcare settings. In one notable outbreak, 10 neonates developed fungemia caused by genetically similar L. elongisporus strains over a 6-month period, with environmental sampling confirming colonization of hospital equipment including rails and temperature panels of open care warmers .
What are the primary risk factors and clinical manifestations of L. elongisporus infections?
Based on documented cases, the primary risk factors for L. elongisporus infections include:
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Indwelling central venous catheters
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Immunosuppression
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Extended hospitalization
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Comorbidities such as cancer
The predominant clinical manifestation is catheter-related bloodstream infection (CR-BSI), as documented in multiple case reports . The pathogen's ability to form biofilms, although reported as limited in some phenotypic analyses of single strains, is suggested by its isolation from catheter tips in clinical settings . This biofilm formation capability likely contributes to its pathogenicity in catheter-associated infections, similar to the well-documented mechanism in C. parapsilosis .
What is known about the sexual reproduction capabilities of L. elongisporus and how does this influence its genetic diversity?
L. elongisporus demonstrates a unique reproductive biology among pathogenic yeasts. While initially suggested to be homothallic (self-fertile), detailed characterization of its sexual reproductive structures was only recently accomplished . The species forms asci containing multiple ascospores, with each ascus typically containing one, rarely two, long-ellipsoid ascospores .
Despite the incomplete mating loci, multiple L. elongisporus strains (including bloodstream isolates) developed asci containing multiple ascospores on acetate ascospore agar, confirming sexual reproduction capability . Population genetic analyses have revealed loss of heterozygosity and signatures of recombination (including phylogenetic incompatibility and linkage equilibrium) in clinical and environmental populations, consistent with secondary homothallism and/or frequent mitotic recombination .
What are the most reliable laboratory methods for identifying L. elongisporus in clinical samples?
The identification of L. elongisporus presents significant challenges due to its close resemblance to C. parapsilosis. Based on the research data, the following methodological approach is recommended:
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Initial Screening: Culture on Sabouraud dextrose agar produces white to cream-colored colonies similar to C. parapsilosis .
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Chromogenic Differentiation: Subculture on CHROMagar shows distinctive turquoise blue colonies for L. elongisporus versus white to pale pink for C. parapsilosis . This provides a crucial visual differentiation.
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Molecular Confirmation:
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MALDI-TOF MS: Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry has been demonstrated as a reliable method for identifying members of the C. parapsilosis complex, including L. elongisporus, to the species level .
Conventional biochemical methods including API 20C, ID 32C, and Vitek 2 systems frequently misidentify L. elongisporus as C. parapsilosis and should not be relied upon for definitive identification .
What is the antifungal susceptibility profile of L. elongisporus and how does it compare to related Candida species?
L. elongisporus demonstrates a distinct antifungal susceptibility profile compared to closely related species, particularly C. parapsilosis. Based on clinical isolate testing, L. elongisporus is generally susceptible to multiple antifungal drug classes:
A notable clinical distinction is that L. elongisporus demonstrates higher susceptibility to echinocandins compared to C. parapsilosis. This difference is attributed to the unique amino acid sequence of beta-1,3 glucan synthase (the target of echinocandins) in C. parapsilosis . This differential susceptibility highlights the importance of accurate species identification, as misidentification could lead to suboptimal treatment choices.
What treatment approaches are most effective for L. elongisporus infections based on clinical outcomes?
The limited clinical data available suggests a two-pronged approach is most effective for treating L. elongisporus fungemia:
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Catheter management: Removal of the indwelling catheter appears crucial for successful treatment outcomes in catheter-related bloodstream infections .
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Antifungal therapy: While specific treatment guidelines for L. elongisporus are not established, the organism's susceptibility profile suggests several effective options:
Clinical outcomes have been variable, with some cases responding well to catheter removal and antifungal therapy, while others have been fatal due to underlying comorbidities . In one documented case, a patient with lung cancer and L. elongisporus fungemia died before catheter removal or antifungal treatment could be initiated .
What is the role of crista junction proteins in mitochondrial function and cellular metabolism?
Mitochondrial cristae are connected to the inner boundary membrane via structures called crista junctions, which play critical roles in:
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Regulation of oxidative phosphorylation
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Apoptotic signaling pathways
The formation of these junctions is determined by the MICOS (Mitochondrial Contact Site and Cristae Organizing System) complex, a multi-protein assembly that maintains proper mitochondrial architecture .
How do mutations in crista junction proteins affect cellular physiology and disease pathogenesis?
Research using CRISPR/Cas gene editing to create knockout cell lines has demonstrated that deletion of MIC13 (also termed Qil1), a key subunit of the MICOS complex, results in complete loss of crista junctions . This finding establishes MIC13 as strictly required for crista junction formation.
The functional consequences of these structural alterations include:
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Moderate reduction in mitochondrial respiration
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Perturbation of mitochondrial membrane architecture
Specifically, MIC13 is required for the assembly of MIC10, MIC26, and MIC27 into the MICOS complex but is not needed for the formation of the MIC60/MIC19/MIC25 subcomplex . This suggests that the latter subcomplex alone is insufficient for crista junction formation.
Interestingly, the assembly of respiratory chain supercomplexes remains independent of mitochondrial cristae shape, indicating separate regulatory mechanisms for these structures .
What experimental approaches are most effective for investigating the pathogenesis mechanisms of L. elongisporus?
For researchers seeking to investigate L. elongisporus pathogenicity, a multi-methodological approach is recommended:
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Genomic Analysis: Whole genome sequencing and comparative genomics with related species can identify virulence-associated genes. Analysis of Indian isolates revealed important insights into mating loci and recombination patterns .
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Biofilm Formation Assays: Despite limited biofilm formation in single-strain analyses, isolation from catheter tips suggests this capability exists in clinical strains. Quantitative biofilm assays comparing clinical versus environmental isolates could elucidate this virulence mechanism .
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Infection Transmission Investigation: Environmental sampling coupled with genomic analysis has successfully traced hospital transmission routes, as demonstrated in a neonatal outbreak where L. elongisporus was isolated from both patients and hospital equipment .
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Antifungal Resistance Mechanisms: Investigation of elevated MICs to fluconazole in environmental isolates and to sodium hypochlorite in clinical isolates would provide valuable insights into adaptive resistance mechanisms .
What are the current gaps in understanding the relationship between fungal metabolism and mitochondrial structure?
While research has established the importance of crista junction proteins in mammalian cells, several key questions remain unexplored regarding fungal mitochondrial dynamics:
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Comparative Mitochondrial Biology: How do crista junction structures differ between pathogenic fungi and mammalian cells? Do these differences present potential drug targets?
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Stress Adaptation: How do mitochondrial structural changes in pathogenic fungi like L. elongisporus respond to host-derived stresses or antifungal treatments?
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Metabolic Flexibility: What role might crista remodeling play in the ability of opportunistic fungi to adapt to diverse host environments?
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Therapeutic Targeting: Could disruption of fungal-specific aspects of mitochondrial architecture provide novel antifungal strategies?
Development of fungi-specific mitochondrial imaging techniques and adaptation of CRISPR-based gene editing for L. elongisporus would significantly advance these research directions.
What are the most promising areas for future research on L. elongisporus and crista junction biology?
Based on current knowledge gaps, the following research priorities emerge:
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Standardized Identification Protocols: Development of reliable, accessible methods for accurate identification of L. elongisporus in clinical settings.
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Transmission Dynamics: Further investigation of environmental reservoirs and hospital transmission routes to inform infection control strategies.
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Genetic Manipulation Systems: Establishment of robust gene editing tools specifically for L. elongisporus to enable detailed functional genomic studies.
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Mitochondrial Biology in Fungal Pathogens: Comparative analysis of crista junction proteins across fungal species with varying pathogenicity profiles.
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Host-Pathogen Interactions: Characterization of how L. elongisporus interacts with host immune defenses and how these interactions differ from other Candida species.
