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Gutierrez-Perez C, Puerner C, Jones JT, Vellanki S, Vesely EM, Xatse MA, Viera AFC, Olsen CP, Attiku KO, Cardinale S, Kwasny SM, G-Dayanandan N, Opperman TJ, Cramer RA. Unsaturated fatty acid perturbation combats emerging triazole antifungal resistance in the human fungal pathogen Aspergillus fumigatus. mBio 2024; 15:e0116624. [PMID: 38934618 PMCID: PMC11253624 DOI: 10.1128/mbio.01166-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Accepted: 05/02/2024] [Indexed: 06/28/2024] Open
Abstract
Contemporary antifungal therapies utilized to treat filamentous fungal infections are inhibited by intrinsic and emerging drug resistance. Consequently, there is an urgent need to develop novel antifungal compounds that are effective against drug-resistant filamentous fungi. Here, we utilized an Aspergillus fumigatus cell-based high-throughput screen to identify small molecules with antifungal activity that also potentiated triazole activity. The screen identified 16 hits with promising activity against A. fumigatus. A nonspirocyclic piperidine, herein named MBX-7591, exhibited synergy with triazole antifungal drugs and activity against pan-azole-resistant A. fumigatus isolates. MBX-7591 has additional potent activity against Rhizopus species and CO2-dependent activity against Cryptococcus neoformans. Chemical, genetic, and biochemical mode of action analyses revealed that MBX-7591 increases cell membrane saturation by decreasing oleic acid content. MBX-7591 has low toxicity in vivo and shows good efficacy in decreasing fungal burden in a murine model of invasive pulmonary aspergillosis. Taken together, our results suggest MBX-7591 is a promising hit with a novel mode of action for further antifungal drug development to combat the rising incidence of triazole-resistant filamentous fungal infections.IMPORTANCEThe incidence of infections caused by fungi continues to increase with advances in medical therapies. Unfortunately, antifungal drug development has not kept pace with the incidence and importance of fungal infections, with only three major classes of antifungal drugs currently available for use in the clinic. Filamentous fungi, also called molds, are particularly recalcitrant to contemporary antifungal therapies. Here, a recently developed Aspergillus fumigatus cell reporter strain was utilized to conduct a high-throughput screen to identify small molecules with antifungal activity. An emphasis was placed on small molecules that potentiated the activity of contemporary triazole antifungals and led to the discovery of MBX-7591. MBX-7591 potentiates triazole activity against drug-resistant molds such as A. fumigatus and has activity against Mucorales fungi. MBX-7591's mode of action involves inhibiting the conversion of saturated to unsaturated fatty acids, thereby impacting fungal membrane integrity. MBX-7591 is a novel small molecule with antifungal activity poised for lead development.
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Affiliation(s)
- Cecilia Gutierrez-Perez
- Microbiology and Immunology Department, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire, USA
| | - Charles Puerner
- Microbiology and Immunology Department, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire, USA
| | - Jane T. Jones
- Microbiology and Immunology Department, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire, USA
| | - Sandeep Vellanki
- Microbiology and Immunology Department, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire, USA
| | - Elisa M. Vesely
- Microbiology and Immunology Department, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire, USA
| | - Mark A. Xatse
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts, USA
| | - Andre F. C. Viera
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts, USA
| | - Carissa P. Olsen
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts, USA
| | - Keren O. Attiku
- Microbiology and Immunology Department, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire, USA
| | | | | | | | | | - Robert A. Cramer
- Microbiology and Immunology Department, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire, USA
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2
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Wang CW, Chen RH, Chen YK. The lipid droplet assembly complex consists of seipin and four accessory factors in budding yeast. J Biol Chem 2024; 300:107534. [PMID: 38981533 DOI: 10.1016/j.jbc.2024.107534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 06/12/2024] [Accepted: 06/25/2024] [Indexed: 07/11/2024] Open
Abstract
Seipin, a crucial protein for cellular lipid droplet (LD) assembly, oligomerizes at the interface between the endoplasmic reticulum and LDs to facilitate neutral lipid packaging. Using proximity labeling, we identified four proteins-Ldo45, Ldo16, Tgl4, and Pln1-that are recruited to the vicinity of yeast seipin, the Sei1-Ldb16 complex, exclusively when seipin function is intact, hence termed seipin accessory factors. Localization studies identified Tgl4 at the endoplasmic reticulum-LD contact site, in contrast to Ldo45, Ldo16, and Pln1 at the LD surface. Cells with compromised seipin function resulted in uneven distribution of these proteins with aberrant LDs, supporting a central role of seipin in orchestrating their association with the LD. Overexpression of any seipin accessory factor causes LD aggregation and affects a subset of LD protein distribution, highlighting the importance of their stoichiometry. Although single factor mutations show minor LD morphology changes, the combined mutations have additive effects. Lastly, we present evidence that seipin accessory factors assemble and interact with seipin in the absence of neutral lipids and undergo dynamical rearrangements during LD formation induction, with Ldo45 acting as a central hub recruiting other factors to interact with the seipin complex.
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Affiliation(s)
- Chao-Wen Wang
- Department of Life Sciences, National Cheng Kung University, Tainan, Taiwan.
| | - Rey-Huei Chen
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Yu-Kai Chen
- Department of Life Sciences, National Cheng Kung University, Tainan, Taiwan
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3
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Coates HW, Nguyen TB, Du X, Olzomer EM, Farrell R, Byrne FL, Yang H, Brown AJ. The constitutively active form of a key cholesterol synthesis enzyme is lipid droplet-localized and upregulated in endometrial cancer tissues. J Biol Chem 2024; 300:107232. [PMID: 38537696 PMCID: PMC11061744 DOI: 10.1016/j.jbc.2024.107232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Accepted: 03/18/2024] [Indexed: 04/26/2024] Open
Abstract
Cholesterol is essential for both normal cell viability and cancer cell proliferation. Aberrant activity of squalene monooxygenase (SM, also known as squalene epoxidase), the rate-limiting enzyme of the committed cholesterol synthesis pathway, is accordingly implicated in a growing list of cancers. We previously reported that hypoxia triggers the truncation of SM to a constitutively active form, thus preserving sterol synthesis during oxygen shortfalls. Here, we show SM truncation is upregulated and correlates with the magnitude of hypoxia in endometrial cancer tissues, supporting the in vivo relevance of our earlier work. To further investigate the pathophysiological consequences of SM truncation, we examined its lipid droplet-localized pool using complementary immunofluorescence and cell fractionation approaches and found that it exclusively comprises the truncated enzyme. This partitioning is facilitated by the loss of an endoplasmic reticulum-embedded region at the SM N terminus, whereas the catalytic domain containing membrane-associated C-terminal helices is spared. Moreover, we determined multiple amphipathic helices contribute to the lipid droplet localization of truncated SM. Taken together, our results expand on the striking differences between the two forms of SM and suggest upregulated truncation may contribute to SM-related oncogenesis.
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Affiliation(s)
- Hudson W Coates
- School of Biotechnology and Biomolecular Sciences, UNSW, Sydney, New South Wales, Australia
| | - Tina B Nguyen
- School of Biotechnology and Biomolecular Sciences, UNSW, Sydney, New South Wales, Australia
| | - Ximing Du
- School of Biotechnology and Biomolecular Sciences, UNSW, Sydney, New South Wales, Australia
| | - Ellen M Olzomer
- School of Biotechnology and Biomolecular Sciences, UNSW, Sydney, New South Wales, Australia
| | - Rhonda Farrell
- Chris O'Brien Lifehouse, Camperdown, New South Wales, Australia; Prince of Wales Private Hospital, Randwick, New South Wales, Australia
| | - Frances L Byrne
- School of Biotechnology and Biomolecular Sciences, UNSW, Sydney, New South Wales, Australia
| | - Hongyuan Yang
- School of Biotechnology and Biomolecular Sciences, UNSW, Sydney, New South Wales, Australia
| | - Andrew J Brown
- School of Biotechnology and Biomolecular Sciences, UNSW, Sydney, New South Wales, Australia.
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4
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Sui X, Cheng X, Li Z, Wang Y, Zhang Z, Yan R, Chang L, Li Y, Xu P, Duan C. Quantitative proteomics revealed the transition of ergosterol biosynthesis and drug transporters processes during the development of fungal fluconazole resistance. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2023; 1866:194953. [PMID: 37307946 DOI: 10.1016/j.bbagrm.2023.194953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 05/06/2023] [Accepted: 06/03/2023] [Indexed: 06/14/2023]
Abstract
Fungal infections and antifungal resistance are the increasing global public health concerns. Mechanisms of fungal resistance include alterations in drug-target interactions, detoxification by high expression of drug efflux transporters, and permeability barriers associated with biofilms. However, the systematic panorama and dynamic changes of the relevant biological processes of fungal drug resistance acquisition remain limited. In this study, we developed a yeast model of resistance to prolonged fluconazole treatment and utilized the isobaric labels TMT (tandem mass tag)-based quantitative proteomics to analyze the proteome composition and changes in native, short-time fluconazole stimulated and drug-resistant strains. The proteome exhibited significant dynamic range at the beginning of treatment but returned to normal condition upon acquisition drug resistance. The sterol pathway responded strongly under a short time of fluconazole treatment, with increased transcript levels of most enzymes facilitating greater protein expression. With the drug resistance acquisition, the sterol pathway returned to normal state, while the expression of efflux pump proteins increased obviously on the transcription level. Finally, multiple efflux pump proteins showed high expression in drug-resistant strain. Thus, families of sterol pathway and efflux pump proteins, which are closely associated with drug resistance mechanisms, may play different roles at different nodes in the process of drug resistance acquisition. Our findings uncover the relatively important role of efflux pump proteins in the acquisition of fluconazole resistance and highlight its potential as the vital antifungal targets.
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Affiliation(s)
- Xinying Sui
- Department of Cell Biology and Genetics, Molecular Medicine and Cancer Research Center, Chongqing Medical University, Chongqing, 400016, China; State Key Laboratory of Proteomics, Beijing Proteome Reesearch Center, National Center for Protein Sciences Beijing, Research Unit of Proteomics & Research and Development of New Drug of Chinese Academy of Medical Sciences, Institute of Lifeomics, Beijing 102206, China
| | - Xinyu Cheng
- Anhui Medical University School of Basic Medicine, Hefei 230032, Anhui, China
| | - Zhaodi Li
- Department of Cell Biology and Genetics, Molecular Medicine and Cancer Research Center, Chongqing Medical University, Chongqing, 400016, China; State Key Laboratory of Proteomics, Beijing Proteome Reesearch Center, National Center for Protein Sciences Beijing, Research Unit of Proteomics & Research and Development of New Drug of Chinese Academy of Medical Sciences, Institute of Lifeomics, Beijing 102206, China
| | - Yonghong Wang
- Department of Biomedicine, School of Medicine, Guizhou University, Guiyang 550025, China
| | - Zhenpeng Zhang
- State Key Laboratory of Proteomics, Beijing Proteome Reesearch Center, National Center for Protein Sciences Beijing, Research Unit of Proteomics & Research and Development of New Drug of Chinese Academy of Medical Sciences, Institute of Lifeomics, Beijing 102206, China
| | - Ruyue Yan
- State Key Laboratory of Proteomics, Beijing Proteome Reesearch Center, National Center for Protein Sciences Beijing, Research Unit of Proteomics & Research and Development of New Drug of Chinese Academy of Medical Sciences, Institute of Lifeomics, Beijing 102206, China; Department of Toxicology, School of Public Health, China Medical University, Shenyang, 110122, PR China
| | - Lei Chang
- State Key Laboratory of Proteomics, Beijing Proteome Reesearch Center, National Center for Protein Sciences Beijing, Research Unit of Proteomics & Research and Development of New Drug of Chinese Academy of Medical Sciences, Institute of Lifeomics, Beijing 102206, China
| | - Yanchang Li
- State Key Laboratory of Proteomics, Beijing Proteome Reesearch Center, National Center for Protein Sciences Beijing, Research Unit of Proteomics & Research and Development of New Drug of Chinese Academy of Medical Sciences, Institute of Lifeomics, Beijing 102206, China; Anhui Medical University School of Basic Medicine, Hefei 230032, Anhui, China.
| | - Ping Xu
- State Key Laboratory of Proteomics, Beijing Proteome Reesearch Center, National Center for Protein Sciences Beijing, Research Unit of Proteomics & Research and Development of New Drug of Chinese Academy of Medical Sciences, Institute of Lifeomics, Beijing 102206, China; Anhui Medical University School of Basic Medicine, Hefei 230032, Anhui, China; Department of Biomedicine, School of Medicine, Guizhou University, Guiyang 550025, China; Department of Toxicology, School of Public Health, China Medical University, Shenyang, 110122, PR China.
| | - Changzhu Duan
- Department of Cell Biology and Genetics, Molecular Medicine and Cancer Research Center, Chongqing Medical University, Chongqing, 400016, China.
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Doss EM, Moore JM, Harman BH, Doud EH, Rubenstein EM, Bernstein DA. Characterization of endoplasmic reticulum-associated degradation in the human fungal pathogen Candida albicans. PeerJ 2023; 11:e15897. [PMID: 37645016 PMCID: PMC10461541 DOI: 10.7717/peerj.15897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Accepted: 07/24/2023] [Indexed: 08/31/2023] Open
Abstract
Background Candida albicans is the most prevalent human fungal pathogen. In immunocompromised individuals, C. albicans can cause serious systemic disease, and patients infected with drug-resistant isolates have few treatment options. The ubiquitin-proteasome system has not been thoroughly characterized in C. albicans. Research from other organisms has shown ubiquitination is important for protein quality control and regulated protein degradation at the endoplasmic reticulum (ER) via ER-associated protein degradation (ERAD). Methods Here we perform the first characterization, to our knowledge, of ERAD in a human fungal pathogen. We generated functional knockouts of C. albicans genes encoding three proteins predicted to play roles in ERAD, the ubiquitin ligases Hrd1 and Doa10 and the ubiquitin-conjugating enzyme Ubc7. We assessed the fitness of each mutant in the presence of proteotoxic stress, and we used quantitative tandem mass tag mass spectrometry to characterize proteomic alterations in yeast lacking each gene. Results Consistent with a role in protein quality control, yeast lacking proteins thought to contribute to ERAD displayed hypersensitivity to proteotoxic stress. Furthermore, each mutant displayed distinct proteomic profiles, revealing potential physiological ERAD substrates, co-factors, and compensatory stress response factors. Among candidate ERAD substrates are enzymes contributing to ergosterol synthesis, a known therapeutic vulnerability of C. albicans. Together, our results provide the first description of ERAD function in C. albicans, and, to our knowledge, any pathogenic fungus.
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Affiliation(s)
- Ellen M. Doss
- Department of Biology, Ball State University, Muncie, Indiana, United States
- Mode of Action and Resistance Management Center of Expertise, Corteva Agriscience, Indianapolis, Indiana, United States
| | - Joshua M. Moore
- Department of Biology, Ball State University, Muncie, Indiana, United States
| | - Bryce H. Harman
- Department of Biology, Ball State University, Muncie, Indiana, United States
| | - Emma H. Doud
- Center for Proteome Analysis, Indiana University School of Medicine, Indianapolis, Indiana, United States
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - Eric M. Rubenstein
- Department of Biology, Ball State University, Muncie, Indiana, United States
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Turk SM, Indovina CJ, Miller JM, Overton DL, Runnebohm AM, Orchard CJ, Tragesser-Tiña ME, Gosser SK, Doss EM, Richards KA, Irelan CB, Daraghmi MM, Bailey CG, Niekamp JM, Claypool KP, Engle SM, Buchanan BW, Woodruff KA, Olesen JB, Smaldino PJ, Rubenstein EM. Lipid biosynthesis perturbation impairs endoplasmic reticulum-associated degradation. J Biol Chem 2023; 299:104939. [PMID: 37331602 PMCID: PMC10372827 DOI: 10.1016/j.jbc.2023.104939] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 06/02/2023] [Accepted: 06/09/2023] [Indexed: 06/20/2023] Open
Abstract
The relationship between lipid homeostasis and protein homeostasis (proteostasis) is complex and remains incompletely understood. We conducted a screen for genes required for efficient degradation of Deg1-Sec62, a model aberrant translocon-associated substrate of the endoplasmic reticulum (ER) ubiquitin ligase Hrd1, in Saccharomyces cerevisiae. This screen revealed that INO4 is required for efficient Deg1-Sec62 degradation. INO4 encodes one subunit of the Ino2/Ino4 heterodimeric transcription factor, which regulates expression of genes required for lipid biosynthesis. Deg1-Sec62 degradation was also impaired by mutation of genes encoding several enzymes mediating phospholipid and sterol biosynthesis. The degradation defect in ino4Δ yeast was rescued by supplementation with metabolites whose synthesis and uptake are mediated by Ino2/Ino4 targets. Stabilization of a panel of substrates of the Hrd1 and Doa10 ER ubiquitin ligases by INO4 deletion indicates ER protein quality control is generally sensitive to perturbed lipid homeostasis. Loss of INO4 sensitized yeast to proteotoxic stress, suggesting a broad requirement for lipid homeostasis in maintaining proteostasis. A better understanding of the dynamic relationship between lipid homeostasis and proteostasis may lead to improved understanding and treatment of several human diseases associated with altered lipid biosynthesis.
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Affiliation(s)
- Samantha M Turk
- Department of Biology, Ball State University, Muncie, Indiana, USA
| | | | - Jacob M Miller
- Department of Biology, Ball State University, Muncie, Indiana, USA
| | | | | | - Cade J Orchard
- Department of Biology, Ball State University, Muncie, Indiana, USA
| | | | | | - Ellen M Doss
- Department of Biology, Ball State University, Muncie, Indiana, USA
| | - Kyle A Richards
- Department of Biology, Ball State University, Muncie, Indiana, USA
| | | | | | - Connor G Bailey
- Department of Biology, Ball State University, Muncie, Indiana, USA
| | - Julia M Niekamp
- Department of Biology, Ball State University, Muncie, Indiana, USA
| | | | - Sarah M Engle
- Department of Biology, Ball State University, Muncie, Indiana, USA
| | - Bryce W Buchanan
- Department of Biology, Ball State University, Muncie, Indiana, USA
| | | | - James B Olesen
- Department of Biology, Ball State University, Muncie, Indiana, USA
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7
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Greenwood BL, Luo Z, Ahmed T, Huang D, Stuart DT. Saccharomyces cerevisiae Δ9-desaturase Ole1 forms a supercomplex with Slc1 and Dga1. J Biol Chem 2023:104882. [PMID: 37269945 PMCID: PMC10302205 DOI: 10.1016/j.jbc.2023.104882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Revised: 05/04/2023] [Accepted: 05/07/2023] [Indexed: 06/05/2023] Open
Abstract
Biosynthesis of the various lipid species that compose cellular membranes and lipid droplets depends on the activity of multiple enzymes functioning in coordinated pathways. The flux of intermediates through lipid biosynthetic pathways is regulated to respond to nutritional and environmental demands placed on the cell necessitating that there be extensive flexibility in pathway activity and organization. This flexibility can in part be achieved through the organization of biosynthetic enzymes into metabolon supercomplexes. However, the composition and organization of such supercomplexes remains unclear. Here, we identified protein-protein interactions between acyltransferases Sct1, Gpt2, Slc1, Dga1 and the Δ9 acyl-CoA desaturase Ole1 in Saccharomyces cerevisiae. We further determined that a subset of these acyltransferases interact with each other without Ole1 acting as a scaffold. We show that truncated versions of Dga1 lacking the carboxyl-terminal 20 amino acid residues are non-functional and unable to bind Ole1. Furthermore, charged-to-alanine scanning mutagenesis revealed that a cluster of charged residues near the carboxyl-terminus were required for the interaction with Ole1. Mutation of these charged residues disrupted the interaction between Dga1 and Ole1, but allowed Dga1 to retain catalytic activity and to induce lipid droplet formation. These data support the formation of a complex of acyltransferases involved in lipid biosynthesis that interacts with Ole1, the sole acyl-CoA desaturase in S. cerevisiae, that can channel unsaturated acyl-chains toward phospholipid or triacylglycerol synthesis. This desaturasome complex may provide the architecture that allows for the necessary flux of de novo synthesized unsaturated acyl-CoA to phospholipid or triacylglycerol synthesis as demanded by cellular requirements.
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Affiliation(s)
- Brianna L Greenwood
- Department of Biochemistry, 561 Medical Sciences Building, University of Alberta, Edmonton AB, T6G 2R3, Canada
| | - Zijun Luo
- Department of Biochemistry, 561 Medical Sciences Building, University of Alberta, Edmonton AB, T6G 2R3, Canada
| | - Tareq Ahmed
- Department of Biochemistry, 561 Medical Sciences Building, University of Alberta, Edmonton AB, T6G 2R3, Canada
| | - Daniel Huang
- Department of Biochemistry, 561 Medical Sciences Building, University of Alberta, Edmonton AB, T6G 2R3, Canada
| | - David T Stuart
- Department of Biochemistry, 561 Medical Sciences Building, University of Alberta, Edmonton AB, T6G 2R3, Canada.
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