RNA-dependent synthesis of ergosteryl-3β-O-glycine in Ascomycota expands the diversity of steryl-amino acids

Yakobov, Nathaniel; Mahmoudi, Nassira; Grob, Guillaume; Yokokawa, Daisuke; Saga, Yusuke; Kushiro, Toshio; Worrell, Danielle; Roy, Hervé; Schaller, Hubert; Senger, Bruno; Huck, Laurence; Gascon, Gisela Riera; Becker, Hubert Dominique; Fischer, Frédéric

doi:10.1016/j.jbc.2022.101657

Cited by 5 publications

(4 citation statements)

References 71 publications

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“…S2 ). The gene AFUB_085360 encodes the fungal sterol-specific aminoacyl-tRNA transferase (ATT) ergosterol-3β-O-glycine synthase ErgS ( 50 ). This enzyme only uses Gly-tRNA gly to produce an independent glycyl-tRNA synthetase to transfer glycine onto the 3β-OH of ergosterol.…”

Section: Resultsmentioning

confidence: 99%

The C ₂ H ₂ transcription factor SltA is required for germination and hyphal development in Aspergillus fumigatus

Baltussen

Rhijn

Coolen

et al. 2023

mSphere

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Germination of inhaled Aspergillus fumigatus conidia is a necessary sequitur for infection. Germination of conidia starts with the breaking of dormancy, which is initiated by an increase of the cellular perimeter in a process termed isotropic growth. This swelling phase is followed by polarized growth, resulting in the formation of a germ tube. The multinucleate tubular cells exhibit tip growth from the hyphae, after which lateral branches emerge to form the mycelial network. The regulatory mechanisms governing conidial germination are not well defined. In this study, we identified a novel role for the transcription factor SltA in the orchestration of germination and hyphal development. Conidia lacking sltA fail to appropriately regulate isotropic growth and begin to swell earlier and subsequently switch to polarized growth faster. Additionally, hyphal development is distorted in a ∆ sltA isolate as hyphae are hyper-branching and wider, and show branching at the apical tip. ∆ sltA conidia are more tolerant to cell wall stressors on minimal medium compared to the wild-type (WT) strain. A transcriptome analysis of different stages of early growth was carried out to assess the regulatory role of SltA. Null mutants generated for three of the most dysregulated genes showed rapid germ tube emergence. Distinct from the phenotype observed for ∆ sltA , conidia from these strains lacked defects in isotropic growth, but switched to polarized growth faster. Here, we characterize and describe several genes in the regulon of SltA, highlighting the complex nature of germination. IMPORTANCE Aspergillus fumigatus is the main human fungal pathogen causing aspergillosis. For this fungus, azoles are the most commonly used antifungal drugs for treatment of aspergillosis. However, the prevalence of azole resistance is alarmingly increasing and linked with elevated mortality. Germination of conidia is crucial within its asexual life cycle and plays a critical role during the infection in the human host. Precluding germination could be a promising strategy considering the role of germination in Aspergillus spp. pathogenicity. Here, we identify a novel role for SltA in appropriate maintenance of dormancy, germination, and hyphal development. Three genes in the regulon of SltA were also essential for appropriate germination of conidia. With an expanding knowledge of germination and its different morphotypes, more advances can be made toward potential anti-germination targets for therapy.

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Section: Resultsmentioning

confidence: 99%

The C ₂ H ₂ transcription factor SltA is required for germination and hyphal development in Aspergillus fumigatus

Baltussen

Rhijn

Coolen

et al. 2023

mSphere

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“…Since the initial discovery of MprF in S. aureus , a family of orthologs has been uncovered, with members appearing in the genomes of most bacterial phyla, in archaea ( 5 ), and, most recently, in fungal pathogens ( 6 – 8 ). Members of this family of proteins exhibit differing specificities for both the aa’s and lipids that are used as substrates.…”

Section: Introductionmentioning

confidence: 99%

“…Members of this family of proteins exhibit differing specificities for both the aa’s and lipids that are used as substrates. Lipid modification by Lys and Ala ( 9 , 10 ) has been described in various bacterial species, while Gly and Asp are substrates used by the fungal proteins ( 6 – 8 ). Likewise, some of these enzymes act on lipids that are distinct from PG, such as cardiolipin in proteobacteria ( 11 , 12 ) and diacylglycerol (DAG) in Corynebacterium glutamicum ( 1 3 ).…”

Section: Introductionmentioning

confidence: 99%

“…Likewise, some of these enzymes act on lipids that are distinct from PG, such as cardiolipin in proteobacteria ( 11 , 12 ) and diacylglycerol (DAG) in Corynebacterium glutamicum ( 1 3 ). The more distant MprF orthologs found in fungi aminoacylate a sterol (i.e., ergosterol) instead of a glycerolipid (e.g., PG, DAG, or cardiolipin) ( 6 – 8 , 14 ), demonstrating the substrate diversity among this family of proteins.…”

Section: Introductionmentioning

confidence: 99%

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The MprF homolog LysX synthesizes lysyl-diacylglycerol contributing to antibiotic resistance and virulence

Gill,

Phan,

Platt

et al. 2023

Microbiol Spectr

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Lysyl-diacylglycerol (Lys-DAG) was identified three decades ago in Mycobacterium phlei , but the biosynthetic pathway and function of this aminoacylated lipid have since remained uncharacterized. Combining genetic methods, mass spectrometry, and biochemical approaches, we show that the multiple peptide resistance factor (MprF) homolog LysX from Corynebacterium pseudotuberculosis and two mycobacterial species is responsible for Lys-DAG synthesis. LysX is conserved in most Actinobacteria and was previously implicated in the synthesis of another modified lipid, lysyl-phosphatidylglycerol (Lys-PG), in Mycobacterium tuberculosis . Although we detected low levels of Lys-PG in the membrane of C. pseudotuberculosis , our data suggest that Lys-PG is not directly synthesized by LysX and may require an additional downstream pathway, which is as yet undefined. Our results show that LysX in C. pseudotuberculosis is a major factor of resistance against a variety of positively charged antibacterial agents, including cationic antimicrobial peptides (e.g., human peptide LL-37 and polymyxin B) and aminoglycosides (e.g., gentamycin and apramycin). Deletion of lysX caused an increase in cellular membrane permeability without dissipation of the membrane potential, suggesting that loss of the protein does not result in mechanical damage to the cell membrane. Furthermore, lysX -deficient cells exhibited an attenuated virulence phenotype in a Galleria mellonella infection model, supporting a role for LysX during infection. Altogether, Lys-DAG represents a novel molecular determinant for antimicrobial resistance and virulence that may be widespread in Actinobacteria and points to a richer landscape than previously realized of lipid components contributing to overall membrane physiology in this important bacterial phylum. IMPORTANCE In the past two decades, tRNA-dependent modification of membrane phosphatidylglycerol has been implicated in altering the biochemical properties of the cell surface, thereby enhancing the antimicrobial resistance and virulence of various bacterial pathogens. Here, we show that in several Actinobacteria, the multifunctional protein LysX attaches lysine to diacylglycerol instead of phosphatidylglycerol. We found that lysyl-diacylglycerol (Lys-DAG) confers high levels of resistance against various cationic antimicrobial peptides and aminoglycosides and also enhances virulence. Our data show that Lys-DAG is a lipid commonly found in important actinobacterial pathogens, including Mycobacterium and Corynebacterium species.

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Subterranean termites raise the alarm when their anti-fungal weapon falters

Luitel,

Johnson,

Bulmer

2023

Sci Nat

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RNA-dependent synthesis of ergosteryl-3β-O-glycine in Ascomycota expands the diversity of steryl-amino acids

Cited by 5 publications

References 71 publications

The C ₂ H ₂ transcription factor SltA is required for germination and hyphal development in Aspergillus fumigatus

The C ₂ H ₂ transcription factor SltA is required for germination and hyphal development in Aspergillus fumigatus

The MprF homolog LysX synthesizes lysyl-diacylglycerol contributing to antibiotic resistance and virulence

Subterranean termites raise the alarm when their anti-fungal weapon falters

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RNA-dependent synthesis of ergosteryl-3β-O-glycine in Ascomycota expands the diversity of steryl-amino acids

Cited by 5 publications

References 71 publications

The C 2 H 2 transcription factor SltA is required for germination and hyphal development in Aspergillus fumigatus

The C 2 H 2 transcription factor SltA is required for germination and hyphal development in Aspergillus fumigatus

The MprF homolog LysX synthesizes lysyl-diacylglycerol contributing to antibiotic resistance and virulence

Subterranean termites raise the alarm when their anti-fungal weapon falters

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The C ₂ H ₂ transcription factor SltA is required for germination and hyphal development in Aspergillus fumigatus

The C ₂ H ₂ transcription factor SltA is required for germination and hyphal development in Aspergillus fumigatus