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Ahmady L, Gothwal M, Mukkoli MM, Bari VK. Antifungal drug resistance in Candida: a special emphasis on amphotericin B. APMIS 2024; 132:291-316. [PMID: 38465406 DOI: 10.1111/apm.13389] [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: 06/16/2023] [Accepted: 02/12/2024] [Indexed: 03/12/2024]
Abstract
Invasive fungal infections in humans caused by several Candida species, increased considerably in immunocompromised or critically ill patients, resulting in substantial morbidity and mortality. Candida albicans is the most prevalent species, although the frequency of these organisms varies greatly according to geographic region. Infections with C. albicans and non-albicans Candida species have become more common, especially in the past 20 years, as a result of aging, immunosuppressive medication use, endocrine disorders, malnourishment, extended use of medical equipment, and an increase in immunogenic diseases. Despite C. albicans being the species most frequently associated with human infections, C. glabrata, C. parapsilosis, C. tropicalis, and C. krusei also have been identified. Several antifungal drugs with different modes of action are approved for use in clinical settings to treat fungal infections. However, due to the common eukaryotic structure of humans and fungi, only a limited number of antifungal drugs are available for therapeutic use. Furthermore, drug resistance in Candida species has emerged as a result of the growing use of currently available antifungal drugs against fungal infections. Amphotericin B (AmB), a polyene class of antifungal drugs, is mainly used for the treatment of serious systemic fungal infections. AmB interacts with fungal plasma membrane ergosterol, triggering cellular ion leakage via pore formation, or extracting the ergosterol from the plasma membrane inducing cellular death. AmB resistance is primarily caused by changes in the content or structure of ergosterol. This review summarizes the antifungal drug resistance exhibited by Candida species, with a special focus on AmB.
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Affiliation(s)
- Lailema Ahmady
- Department of Biochemistry, School of Basic Sciences, Central University of Punjab, Bathinda, India
| | - Manisha Gothwal
- Department of Biochemistry, School of Basic Sciences, Central University of Punjab, Bathinda, India
| | | | - Vinay Kumar Bari
- Department of Biochemistry, School of Basic Sciences, Central University of Punjab, Bathinda, India
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2
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Czajka KM, Venkataraman K, Brabant-Kirwan D, Santi SA, Verschoor C, Appanna VD, Singh R, Saunders DP, Tharmalingam S. Molecular Mechanisms Associated with Antifungal Resistance in Pathogenic Candida Species. Cells 2023; 12:2655. [PMID: 37998390 PMCID: PMC10670235 DOI: 10.3390/cells12222655] [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: 10/17/2023] [Revised: 11/14/2023] [Accepted: 11/17/2023] [Indexed: 11/25/2023] Open
Abstract
Candidiasis is a highly pervasive infection posing major health risks, especially for immunocompromised populations. Pathogenic Candida species have evolved intrinsic and acquired resistance to a variety of antifungal medications. The primary goal of this literature review is to summarize the molecular mechanisms associated with antifungal resistance in Candida species. Resistance can be conferred via gain-of-function mutations in target pathway genes or their transcriptional regulators. Therefore, an overview of the known gene mutations is presented for the following antifungals: azoles (fluconazole, voriconazole, posaconazole and itraconazole), echinocandins (caspofungin, anidulafungin and micafungin), polyenes (amphotericin B and nystatin) and 5-fluorocytosine (5-FC). The following mutation hot spots were identified: (1) ergosterol biosynthesis pathway mutations (ERG11 and UPC2), resulting in azole resistance; (2) overexpression of the efflux pumps, promoting azole resistance (transcription factor genes: tac1 and mrr1; transporter genes: CDR1, CDR2, MDR1, PDR16 and SNQ2); (3) cell wall biosynthesis mutations (FKS1, FKS2 and PDR1), conferring resistance to echinocandins; (4) mutations of nucleic acid synthesis/repair genes (FCY1, FCY2 and FUR1), resulting in 5-FC resistance; and (5) biofilm production, promoting general antifungal resistance. This review also provides a summary of standardized inhibitory breakpoints obtained from international guidelines for prominent Candida species. Notably, N. glabrata, P. kudriavzevii and C. auris demonstrate fluconazole resistance.
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Affiliation(s)
- Karolina M. Czajka
- Medical Sciences Division, NOSM University, 935 Ramsey Lake Rd., Sudbury, ON P3E 2C6, Canada; (K.M.C.); (K.V.); (C.V.); (R.S.); (D.P.S.)
| | - Krishnan Venkataraman
- Medical Sciences Division, NOSM University, 935 Ramsey Lake Rd., Sudbury, ON P3E 2C6, Canada; (K.M.C.); (K.V.); (C.V.); (R.S.); (D.P.S.)
- School of Natural Sciences, Laurentian University, Sudbury, ON P3E 2C6, Canada;
| | | | - Stacey A. Santi
- Health Sciences North Research Institute, Sudbury, ON P3E 2H2, Canada; (D.B.-K.); (S.A.S.)
| | - Chris Verschoor
- Medical Sciences Division, NOSM University, 935 Ramsey Lake Rd., Sudbury, ON P3E 2C6, Canada; (K.M.C.); (K.V.); (C.V.); (R.S.); (D.P.S.)
- School of Natural Sciences, Laurentian University, Sudbury, ON P3E 2C6, Canada;
- Health Sciences North Research Institute, Sudbury, ON P3E 2H2, Canada; (D.B.-K.); (S.A.S.)
| | - Vasu D. Appanna
- School of Natural Sciences, Laurentian University, Sudbury, ON P3E 2C6, Canada;
| | - Ravi Singh
- Medical Sciences Division, NOSM University, 935 Ramsey Lake Rd., Sudbury, ON P3E 2C6, Canada; (K.M.C.); (K.V.); (C.V.); (R.S.); (D.P.S.)
- Health Sciences North Research Institute, Sudbury, ON P3E 2H2, Canada; (D.B.-K.); (S.A.S.)
| | - Deborah P. Saunders
- Medical Sciences Division, NOSM University, 935 Ramsey Lake Rd., Sudbury, ON P3E 2C6, Canada; (K.M.C.); (K.V.); (C.V.); (R.S.); (D.P.S.)
- Health Sciences North Research Institute, Sudbury, ON P3E 2H2, Canada; (D.B.-K.); (S.A.S.)
| | - Sujeenthar Tharmalingam
- Medical Sciences Division, NOSM University, 935 Ramsey Lake Rd., Sudbury, ON P3E 2C6, Canada; (K.M.C.); (K.V.); (C.V.); (R.S.); (D.P.S.)
- School of Natural Sciences, Laurentian University, Sudbury, ON P3E 2C6, Canada;
- Health Sciences North Research Institute, Sudbury, ON P3E 2H2, Canada; (D.B.-K.); (S.A.S.)
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Spruijtenburg B, Rudramurthy SM, Meijer EFJ, van Haren MHI, Kaur H, Chakrabarti A, Meis JF, de Groot T. Application of Novel Short Tandem Repeat Typing for Wickerhamomyces anomalus Reveals Simultaneous Outbreaks within a Single Hospital. Microorganisms 2023; 11:1525. [PMID: 37375027 DOI: 10.3390/microorganisms11061525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 05/31/2023] [Accepted: 06/06/2023] [Indexed: 06/29/2023] Open
Abstract
Wickerhamomyces anomalus, previously known as Candida pelliculosa, occasionally causes candidemia in humans, primarily infecting neonates, and infants. The mortality rate of these invasive infections is high, and isolates with a reduced susceptibility to fluconazole have been reported. W. anomalus outbreaks are regularly reported in healthcare facilities, especially in neonatal intensive care units (NICUs). In order to rapidly genotype isolates with a high-resolution, we developed and applied a short tandem repeat (STR) typing scheme for W. anomalus. Six STR markers were selected and amplified in two multiplex PCRs, M3 and M6, respectively. In total, 90 W. anomalus isolates were typed, leading to the identification of 38 different genotypes. Four large clusters were found, unveiling simultaneous outbreak events spread across multiple units within the same hospital. STR typing results of 11 isolates were compared to whole-genome sequencing (WGS) single nucleotide polymorphism (SNP) calling, and the identified genotypic relationships were highly concordant. We performed antifungal susceptibility testing of these isolates, and a reduced susceptibility to fluconazole was found for two (2.3%) isolates. ERG11 genes of these two isolates were examined using WGS data, which revealed a novel I469L substitution in one isolate. By constructing a homology model for W. anomalus ERG11p, the substitution was found in close proximity to the fluconazole binding site. In summary, we showed multiple W. anomalus outbreak events by applying a novel STR genotyping scheme.
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Affiliation(s)
- Bram Spruijtenburg
- Department of Medical Microbiology and Infectious Diseases, Canisius-Wilhelmina Hospital, 6532 SZ Nijmegen, The Netherlands
- Centre of Expertise in Mycology, Radboud University Medical Center/Canisius Wilhelmina Hospital, 6532 SZ Nijmegen, The Netherlands
| | - Shivaprakash M Rudramurthy
- Department of Medical Microbiology, Postgraduate Institute of Medical Education and Research, Chandigarh 160012, India
| | - Eelco F J Meijer
- Department of Medical Microbiology and Infectious Diseases, Canisius-Wilhelmina Hospital, 6532 SZ Nijmegen, The Netherlands
- Centre of Expertise in Mycology, Radboud University Medical Center/Canisius Wilhelmina Hospital, 6532 SZ Nijmegen, The Netherlands
| | - Merlijn H I van Haren
- Department of Medical Microbiology and Infectious Diseases, Canisius-Wilhelmina Hospital, 6532 SZ Nijmegen, The Netherlands
| | - Harsimran Kaur
- Department of Medical Microbiology, Postgraduate Institute of Medical Education and Research, Chandigarh 160012, India
| | - Arunaloke Chakrabarti
- Department of Medical Microbiology, Postgraduate Institute of Medical Education and Research, Chandigarh 160012, India
| | - Jacques F Meis
- Department of Medical Microbiology and Infectious Diseases, Canisius-Wilhelmina Hospital, 6532 SZ Nijmegen, The Netherlands
- Centre of Expertise in Mycology, Radboud University Medical Center/Canisius Wilhelmina Hospital, 6532 SZ Nijmegen, The Netherlands
- Department I of Internal Medicine, University of Cologne, Excellence Center for Medical Mycology, 50931 Cologne, Germany
| | - Theun de Groot
- Department of Medical Microbiology and Infectious Diseases, Canisius-Wilhelmina Hospital, 6532 SZ Nijmegen, The Netherlands
- Centre of Expertise in Mycology, Radboud University Medical Center/Canisius Wilhelmina Hospital, 6532 SZ Nijmegen, The Netherlands
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Nowak M, Skwarecki AS, Pilch J, Górska J, Szweda P, Milewska MJ, Milewski S. Fatty acids as molecular carriers in cleavable antifungal conjugates. Eur J Med Chem 2023; 252:115293. [PMID: 36958265 DOI: 10.1016/j.ejmech.2023.115293] [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: 08/29/2022] [Revised: 03/15/2023] [Accepted: 03/15/2023] [Indexed: 03/18/2023]
Abstract
Conjugates composed of C2-18 fatty acid (FA) residues as a molecular carrier and 5-fluorocytosine (5-FC) as an active agent, released upon the action of intracellular esterases on the ester bond between FA and "trimethyl lock" intramolecular linker, demonstrate good in vitro activity against human pathogenic yeasts of Candida spp. The minimal inhibitory concentrations (MIC) values for the most active conjugates containing caprylic (C8), capric (C10), lauric (C12), or myristic (C14) acid residues were in the 2-64 μg mL-1 range, except for these against the least susceptible Candida krusei. The least active conjugates containing C2, C16, or C18 FA were slowly hydrolyzed by esterase and probably poorly taken up by Candida cells, as found for their analogs containing a fluorescent label, Nap-NH2 instead of 5-FC.
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Affiliation(s)
- Michał Nowak
- Department of Organic Chemistry, Faculty of Chemistry, Gdańsk University of Technology, 11/12 Narutowicza St., 80-233, Gdańsk, Poland.
| | - Andrzej S Skwarecki
- Department of Pharmaceutical Technology and Biochemistry, Faculty of Chemistry, Gdańsk University of Technology, 11/12 Narutowicza St., 80-233, Gdańsk, Poland
| | - Joanna Pilch
- Department of Pharmaceutical Technology and Biochemistry, Faculty of Chemistry, Gdańsk University of Technology, 11/12 Narutowicza St., 80-233, Gdańsk, Poland
| | - Justyna Górska
- Department of Pharmaceutical Technology and Biochemistry, Faculty of Chemistry, Gdańsk University of Technology, 11/12 Narutowicza St., 80-233, Gdańsk, Poland
| | - Piotr Szweda
- Department of Pharmaceutical Technology and Biochemistry, Faculty of Chemistry, Gdańsk University of Technology, 11/12 Narutowicza St., 80-233, Gdańsk, Poland
| | - Maria J Milewska
- Department of Organic Chemistry, Faculty of Chemistry, Gdańsk University of Technology, 11/12 Narutowicza St., 80-233, Gdańsk, Poland
| | - Sławomir Milewski
- Department of Pharmaceutical Technology and Biochemistry, Faculty of Chemistry, Gdańsk University of Technology, 11/12 Narutowicza St., 80-233, Gdańsk, Poland
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Similarities and Differences among Species Closely Related to Candida albicans: C. tropicalis, C. dubliniensis, and C. auris. Cell Microbiol 2022. [DOI: 10.1155/2022/2599136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Although Candida species are widespread commensals of the microflora of healthy individuals, they are also among the most important human fungal pathogens that under certain conditions can cause diseases (candidiases) of varying severity ranging from mild superficial infections of the mucous membranes to life-threatening systemic infections. So far, the vast majority of research aimed at understanding the molecular basis of pathogenesis has been focused on the most common species—Candida albicans. Meanwhile, other closely related species belonging to the CTG clade, namely, Candida tropicalis and Candida dubliniensis, are becoming more important in clinical practice, as well as a relatively newly identified species, Candida auris. Despite the close relationship of these microorganisms, it seems that in the course of evolution, they have developed distinct biochemical, metabolic, and physiological adaptations, which they use to fit to commensal niches and achieve full virulence. Therefore, in this review, we describe the current knowledge on C. tropicalis, C. dubliniensis, and C. auris virulence factors, the formation of a mixed species biofilm and mutual communication, the environmental stress response and related changes in fungal cell metabolism, and the effect of pathogens on host defense response and susceptibility to antifungal agents used, highlighting differences with respect to C. albicans. Special attention is paid to common diagnostic problems resulting from similarities between these species and the emergence of drug resistance mechanisms. Understanding the different strategies to achieve virulence, used by important opportunistic pathogens of the genus Candida, is essential for proper diagnosis and treatment.
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Delma FZ, Al-Hatmi AMS, Brüggemann RJM, Melchers WJG, de Hoog S, Verweij PE, Buil JB. Molecular Mechanisms of 5-Fluorocytosine Resistance in Yeasts and Filamentous Fungi. J Fungi (Basel) 2021; 7:jof7110909. [PMID: 34829198 PMCID: PMC8623157 DOI: 10.3390/jof7110909] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 10/19/2021] [Accepted: 10/23/2021] [Indexed: 12/30/2022] Open
Abstract
Effective management and treatment of fungal diseases is hampered by poor diagnosis, limited options for antifungal therapy, and the emergence of antifungal drug resistance. An understanding of molecular mechanisms contributing to resistance is essential to optimize the efficacy of currently available antifungals. In this perspective, one of the oldest antifungals, 5-fluorocytosine (5-FC), has been the focus of recent studies applying advanced genomic and transcriptomic techniques to decipher the order of events at the molecular level that lead to resistance. These studies have highlighted the complexity of resistance and provided new insights that are reviewed in the present paper.
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Affiliation(s)
- Fatima Zohra Delma
- Department of Medical Microbiology, Radboud University Medical Centre, 6252 AG Nijmegen, The Netherlands; (F.Z.D.); (W.J.G.M.); (P.E.V.)
| | - Abdullah M. S. Al-Hatmi
- Natural & Medical Sciences Research Center, University of Nizwa, Nizwa 616, Oman;
- Centre of Expertise in Mycology Radboudumc/CWZ, Radboudumc Center for Infectious Diseases (RCI), 6252 AG Nijmegen, The Netherlands; (R.J.M.B.); (S.d.H.)
- Foundation Atlas of Clinical Fungi, 1214 GP Hilversum, The Netherlands
| | - Roger J. M. Brüggemann
- Centre of Expertise in Mycology Radboudumc/CWZ, Radboudumc Center for Infectious Diseases (RCI), 6252 AG Nijmegen, The Netherlands; (R.J.M.B.); (S.d.H.)
- Department of Pharmacy, Radboud University Medical Center, 6252 AG Nijmegen, The Netherlands
| | - Willem J. G. Melchers
- Department of Medical Microbiology, Radboud University Medical Centre, 6252 AG Nijmegen, The Netherlands; (F.Z.D.); (W.J.G.M.); (P.E.V.)
- Centre of Expertise in Mycology Radboudumc/CWZ, Radboudumc Center for Infectious Diseases (RCI), 6252 AG Nijmegen, The Netherlands; (R.J.M.B.); (S.d.H.)
| | - Sybren de Hoog
- Centre of Expertise in Mycology Radboudumc/CWZ, Radboudumc Center for Infectious Diseases (RCI), 6252 AG Nijmegen, The Netherlands; (R.J.M.B.); (S.d.H.)
- Foundation Atlas of Clinical Fungi, 1214 GP Hilversum, The Netherlands
| | - Paul E. Verweij
- Department of Medical Microbiology, Radboud University Medical Centre, 6252 AG Nijmegen, The Netherlands; (F.Z.D.); (W.J.G.M.); (P.E.V.)
- Centre of Expertise in Mycology Radboudumc/CWZ, Radboudumc Center for Infectious Diseases (RCI), 6252 AG Nijmegen, The Netherlands; (R.J.M.B.); (S.d.H.)
| | - Jochem B. Buil
- Department of Medical Microbiology, Radboud University Medical Centre, 6252 AG Nijmegen, The Netherlands; (F.Z.D.); (W.J.G.M.); (P.E.V.)
- Centre of Expertise in Mycology Radboudumc/CWZ, Radboudumc Center for Infectious Diseases (RCI), 6252 AG Nijmegen, The Netherlands; (R.J.M.B.); (S.d.H.)
- Correspondence: ; Tel.: +31-24-361-4356
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Kell DB. The Transporter-Mediated Cellular Uptake and Efflux of Pharmaceutical Drugs and Biotechnology Products: How and Why Phospholipid Bilayer Transport Is Negligible in Real Biomembranes. Molecules 2021; 26:5629. [PMID: 34577099 PMCID: PMC8470029 DOI: 10.3390/molecules26185629] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 09/03/2021] [Accepted: 09/14/2021] [Indexed: 12/12/2022] Open
Abstract
Over the years, my colleagues and I have come to realise that the likelihood of pharmaceutical drugs being able to diffuse through whatever unhindered phospholipid bilayer may exist in intact biological membranes in vivo is vanishingly low. This is because (i) most real biomembranes are mostly protein, not lipid, (ii) unlike purely lipid bilayers that can form transient aqueous channels, the high concentrations of proteins serve to stop such activity, (iii) natural evolution long ago selected against transport methods that just let any undesirable products enter a cell, (iv) transporters have now been identified for all kinds of molecules (even water) that were once thought not to require them, (v) many experiments show a massive variation in the uptake of drugs between different cells, tissues, and organisms, that cannot be explained if lipid bilayer transport is significant or if efflux were the only differentiator, and (vi) many experiments that manipulate the expression level of individual transporters as an independent variable demonstrate their role in drug and nutrient uptake (including in cytotoxicity or adverse drug reactions). This makes such transporters valuable both as a means of targeting drugs (not least anti-infectives) to selected cells or tissues and also as drug targets. The same considerations apply to the exploitation of substrate uptake and product efflux transporters in biotechnology. We are also beginning to recognise that transporters are more promiscuous, and antiporter activity is much more widespread, than had been realised, and that such processes are adaptive (i.e., were selected by natural evolution). The purpose of the present review is to summarise the above, and to rehearse and update readers on recent developments. These developments lead us to retain and indeed to strengthen our contention that for transmembrane pharmaceutical drug transport "phospholipid bilayer transport is negligible".
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Affiliation(s)
- Douglas B. Kell
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Crown St, Liverpool L69 7ZB, UK;
- Novo Nordisk Foundation Centre for Biosustainability, Technical University of Denmark, Building 220, Kemitorvet, 2800 Kgs Lyngby, Denmark
- Mellizyme Biotechnology Ltd., IC1, Liverpool Science Park, Mount Pleasant, Liverpool L3 5TF, UK
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Galocha M, Costa IV, Teixeira MC. Carrier-Mediated Drug Uptake in Fungal Pathogens. Genes (Basel) 2020; 11:genes11111324. [PMID: 33182427 PMCID: PMC7697741 DOI: 10.3390/genes11111324] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 11/03/2020] [Accepted: 11/07/2020] [Indexed: 12/22/2022] Open
Abstract
Candida, Aspergillus, and Cryptococcus species are the most frequent cause of severe human fungal infections. Clinically relevant antifungal drugs are scarce, and their effectiveness are hampered by the ability of fungal cells to develop drug resistance mechanisms. Drug effectiveness and drug resistance in human pathogens is very often affected by their “transportome”. Many studies have covered a panoply of drug resistance mechanisms that depend on drug efflux pumps belonging to the ATP-Binding Cassette and Major Facilitator Superfamily. However, the study of drug uptake mechanisms has been, to some extent, overlooked in pathogenic fungi. This review focuses on discussing current knowledge on drug uptake systems in fungal pathogens, highlighting the need for further studies on this topic of great importance. The following subjects are covered: (i) drugs imported by known transporter(s) in pathogenic fungi; and (ii) drugs imported by known transporter(s) in the model yeast Saccharomyces cerevisiae or in human parasites, aimed at the identification of their homologs in pathogenic fungi. Besides its contribution to increase the understanding of drug-pathogen interactions, the practical implications of identifying drug importers in human pathogens are discussed, particularly focusing on drug development strategies.
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Affiliation(s)
- Mónica Galocha
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; (M.G.); (I.V.C.)
- Biological Sciences Research Group, iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
| | - Inês Vieira Costa
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; (M.G.); (I.V.C.)
- Biological Sciences Research Group, iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
| | - Miguel Cacho Teixeira
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; (M.G.); (I.V.C.)
- Biological Sciences Research Group, iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
- Correspondence: ; Tel.: +351-21-841-7772; Fax: +351-21-841-9199
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Ciurea CN, Kosovski IB, Mare AD, Toma F, Pintea-Simon IA, Man A. Candida and Candidiasis-Opportunism Versus Pathogenicity: A Review of the Virulence Traits. Microorganisms 2020; 8:microorganisms8060857. [PMID: 32517179 PMCID: PMC7355540 DOI: 10.3390/microorganisms8060857] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 06/03/2020] [Accepted: 06/04/2020] [Indexed: 12/13/2022] Open
Abstract
One of the most important questions in microbiology nowadays, is how apparently harmless, commensal yeasts like Candida spp. can cause a rising number of infections. The occurrence of the disease requires firstly the attachment to the host cells, followed by the invasion of the tissue. The adaptability translates into a rapid ability to respond to stress factors, to take up nutrients or to multiply under different conditions. By forming complex intracellular networks such as biofilms, Candida spp. become not only more refractive to antifungal therapies but also more prone to cause disease. The inter-microbial interactions can enhance the virulence of a strain. In vivo, the fungal cells face a multitude of challenges and, as a result, they develop complex strategies serving one ultimate goal: survival. This review presents the virulence factors of the most important Candida spp., contributing to a better understanding of the onset of candidiasis and raising awareness of the highly complex interspecies interactions that can change the outcome of the disease.
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Affiliation(s)
- Cristina Nicoleta Ciurea
- Department of Microbiology, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Târgu Mureș, 540139 Târgu Mureș, Romania; (A.D.M.); (F.T.); (I.A.P.-S.); (A.M.)
- Doctoral School, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Târgu Mureș, 540139 Târgu Mureș, Romania;
- Correspondence:
| | - Irina-Bianca Kosovski
- Doctoral School, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Târgu Mureș, 540139 Târgu Mureș, Romania;
- Department of Physiopathology, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Târgu Mureș, 540139 Târgu Mureș, Romania
| | - Anca Delia Mare
- Department of Microbiology, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Târgu Mureș, 540139 Târgu Mureș, Romania; (A.D.M.); (F.T.); (I.A.P.-S.); (A.M.)
| | - Felicia Toma
- Department of Microbiology, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Târgu Mureș, 540139 Târgu Mureș, Romania; (A.D.M.); (F.T.); (I.A.P.-S.); (A.M.)
| | - Ionela Anca Pintea-Simon
- Department of Microbiology, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Târgu Mureș, 540139 Târgu Mureș, Romania; (A.D.M.); (F.T.); (I.A.P.-S.); (A.M.)
- Doctoral School, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Târgu Mureș, 540139 Târgu Mureș, Romania;
| | - Adrian Man
- Department of Microbiology, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Târgu Mureș, 540139 Târgu Mureș, Romania; (A.D.M.); (F.T.); (I.A.P.-S.); (A.M.)
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Oliveira JSD, Pereira VS, Castelo-Branco DDSCM, Cordeiro RDA, Sidrim JJC, Brilhante RSN, Rocha MFG. The yeast, the antifungal, and the wardrobe: a journey into antifungal resistance mechanisms of Candida tropicalis. Can J Microbiol 2020; 66:377-388. [PMID: 32319304 DOI: 10.1139/cjm-2019-0531] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Candida tropicalis is a prominent non-Candida albicans Candida species involved in cases of candidemia, mainly causing infections in patients in intensive care units and (or) those presenting neutropenia. In recent years, several studies have reported an increase in the recovery rates of azole-resistant C. tropicalis isolates. Understanding C. tropicalis resistance is of great importance, since resistant strains are implicated in persistent or recurrent and breakthrough infections. In this review, we address the main mechanisms underlying C. tropicalis resistance to the major antifungal classes used to treat candidiasis. The main genetic basis involved in C. tropicalis antifungal resistance is discussed. A better understanding of the epidemiology of resistant strains and the mechanisms involved in C. tropicalis resistance can help improve diagnosis and assessment of the antifungal susceptibility of this Candida species to improve clinical management.
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Affiliation(s)
- Jonathas Sales de Oliveira
- Department of Pathology and Legal Medicine, School of Medicine, Specialized Medical Mycology Center, Graduate Program in Medical Microbiology, Federal University of Ceará, Fortaleza-CE, Brazil
| | - Vandbergue Santos Pereira
- Department of Pathology and Legal Medicine, School of Medicine, Specialized Medical Mycology Center, Graduate Program in Medical Microbiology, Federal University of Ceará, Fortaleza-CE, Brazil
| | - Débora de Souza Collares Maia Castelo-Branco
- Department of Pathology and Legal Medicine, School of Medicine, Specialized Medical Mycology Center, Graduate Program in Medical Microbiology, Federal University of Ceará, Fortaleza-CE, Brazil
| | - Rossana de Aguiar Cordeiro
- Department of Pathology and Legal Medicine, School of Medicine, Specialized Medical Mycology Center, Graduate Program in Medical Microbiology, Federal University of Ceará, Fortaleza-CE, Brazil
| | - José Júlio Costa Sidrim
- Department of Pathology and Legal Medicine, School of Medicine, Specialized Medical Mycology Center, Graduate Program in Medical Microbiology, Federal University of Ceará, Fortaleza-CE, Brazil
| | - Raimunda Sâmia Nogueira Brilhante
- Department of Pathology and Legal Medicine, School of Medicine, Specialized Medical Mycology Center, Graduate Program in Medical Microbiology, Federal University of Ceará, Fortaleza-CE, Brazil
| | - Marcos Fábio Gadelha Rocha
- Department of Pathology and Legal Medicine, School of Medicine, Specialized Medical Mycology Center, Graduate Program in Medical Microbiology, Federal University of Ceará, Fortaleza-CE, Brazil.,School of Veterinary, Postgraduate Program in Veterinary Sciences, State University of Ceará, 1315 Coronel Nunes de Melo Street, Rodolfo Teófilo, CEP 60420-270, Fortaleza-CE, Brazil
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11
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Salazar SB, Simões RS, Pedro NA, Pinheiro MJ, Carvalho MFNN, Mira NP. An Overview on Conventional and Non-Conventional Therapeutic Approaches for the Treatment of Candidiasis and Underlying Resistance Mechanisms in Clinical Strains. J Fungi (Basel) 2020; 6:E23. [PMID: 32050673 PMCID: PMC7151124 DOI: 10.3390/jof6010023] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 02/06/2020] [Accepted: 02/07/2020] [Indexed: 02/06/2023] Open
Abstract
Fungal infections and, in particular, those caused by species of the Candida genus, are growing at an alarming rate and have high associated rates of mortality and morbidity. These infections, generally referred as candidiasis, range from common superficial rushes caused by an overgrowth of the yeasts in mucosal surfaces to life-threatening disseminated mycoses. The success of currently used antifungal drugs to treat candidiasis is being endangered by the continuous emergence of resistant strains, specially among non-albicans Candida species. In this review article, the mechanisms of action of currently used antifungals, with emphasis on the mechanisms of resistance reported in clinical isolates, are reviewed. Novel approaches being taken to successfully inhibit growth of pathogenic Candida species, in particular those based on the exploration of natural or synthetic chemicals or on the activity of live probiotics, are also reviewed. It is expected that these novel approaches, either used alone or in combination with traditional antifungals, may contribute to foster the identification of novel anti-Candida therapies.
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Affiliation(s)
- Sara B. Salazar
- Department of Bioengineering, Institute of Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; (S.B.S.); (R.S.S.); (N.A.P.); (M.J.P.)
| | - Rita S. Simões
- Department of Bioengineering, Institute of Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; (S.B.S.); (R.S.S.); (N.A.P.); (M.J.P.)
| | - Nuno A. Pedro
- Department of Bioengineering, Institute of Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; (S.B.S.); (R.S.S.); (N.A.P.); (M.J.P.)
| | - Maria Joana Pinheiro
- Department of Bioengineering, Institute of Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; (S.B.S.); (R.S.S.); (N.A.P.); (M.J.P.)
| | - Maria Fernanda N. N. Carvalho
- Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal;
| | - Nuno P. Mira
- Department of Bioengineering, Institute of Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; (S.B.S.); (R.S.S.); (N.A.P.); (M.J.P.)
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12
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Dannaoui E, Espinel-Ingroff A. Antifungal Susceptibly Testing by Concentration Gradient Strip Etest Method for Fungal Isolates: A Review. J Fungi (Basel) 2019; 5:jof5040108. [PMID: 31766762 PMCID: PMC6958406 DOI: 10.3390/jof5040108] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 11/13/2019] [Accepted: 11/16/2019] [Indexed: 12/23/2022] Open
Abstract
Antifungal susceptibility testing is an important tool for managing patients with invasive fungal infections, as well as for epidemiological surveillance of emerging resistance. For routine testing in clinical microbiology laboratories, ready-to-use commercial methods are more practical than homemade reference techniques. Among commercially available methods, the concentration gradient Etest strip technique is widely used. It combines an agar-based diffusion method with a dilution method that determinates a minimal inhibitory concentration (MIC) in µg/mL. Many studies have evaluated the agreement between the gradient strip method and the reference methods for both yeasts and filamentous fungi. This agreement has been variable depending on the antifungal, the species, and the incubation time. It has also been shown that the gradient strip method could be a valuable alternative for detection of emerging resistance (non-wild-type isolates) as Etest epidemiological cutoff values have been recently defined for several drug-species combinations. Furthermore, the Etest could be useful for direct antifungal susceptibility testing on blood samples and basic research studies (e.g., the evaluation of the in vitro activity of antifungal combinations). This review summarizes the available data on the performance and potential use of the gradient strip method.
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Affiliation(s)
- Eric Dannaoui
- Paris-Descartes University, Faculty of Medicine, 75006 Paris, France
- APHP, European Georges Pompidou Hospital, Parasitology-Mycology Unit, Microbiology Department, 75015 Paris, France
- Correspondence: ; Tel.: +33-15-6093-948; Fax: +33-15-6092-446
| | - Ana Espinel-Ingroff
- Virginia Commonwealth University (VCU) Medical Center, Richmond, VA 23219, USA;
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13
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Vu K, Thompson GR, Roe CC, Sykes JE, Dreibe EM, Lockhart SR, Meyer W, Engelthaler DM, Gelli A. Flucytosine resistance in Cryptococcus gattii is indirectly mediated by the FCY2-FCY1-FUR1 pathway. Med Mycol 2018; 56:857-867. [PMID: 29554336 PMCID: PMC10905989 DOI: 10.1093/mmy/myx135] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 10/12/2017] [Indexed: 11/14/2022] Open
Abstract
Cryptococcosis is an opportunistic fungal infection caused by members of the two sibling species complexes: Cryptococcus neoformans and Cryptococcus gattii. Flucytosine (5FC) is one of the most widely used antifungals against Cryptococcus spp., yet very few studies have looked at the molecular mechanisms responsible for 5FC resistance in this pathogen. In this study, we examined 11 C. gattii clinical isolates of the major molecular type VGIII based on differential 5FC susceptibility and asked whether there were genomic changes in the key genes involved in flucytosine metabolism. Susceptibility assays and sequencing analysis revealed an association between a point mutation in the cytosine deaminase gene (FCY1) and 5FC resistance in two of the studied 5FC resistant C. gattii VGIII clinical isolates, B9322 and JS5. This mutation results in the replacement of arginine for histidine at position 29 and occurs within a variable stretch of amino acids. Heterologous expression of FCY1 and spot sensitivity assays, however, demonstrated that this point mutation did not have any effect on FCY1 activities and was not responsible for 5FC resistance. Comparative sequence analysis further showed that no changes in the amino acid sequence and no genomic alterations were observed within 1 kb of the upstream and downstream sequences of either cytosine permeases (FCY2-4) or uracil phosphoribosyltransferase (FUR1) genes in 5FC resistant and 5FC susceptible C. gattii VGIII isolates. The herein obtained results suggest that the observed 5FC resistance in the isolates B9322 and JS5 is due to changes in unknown protein(s) or pathway(s) that regulate flucytosine metabolism.
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Affiliation(s)
- Kiem Vu
- Department of Pharmacology, University of California, Davis, California, USA
| | - George R Thompson
- Department of Medical Microbiology and Immunology, University of California, Davis, California, USA
- Department of Internal Medicine, Division of Infectious Diseases, University of California Davis Medical Center, Davis, California, USA
| | - Chandler C Roe
- Translational Genomics Research Institute, Flagstaff, Arizona, USA
| | - Jane E Sykes
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA
| | | | - Shawn R Lockhart
- Mycotic Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia USA
| | - Wieland Meyer
- Molecular Mycology Research Laboratory, Center for Infectious Diseases and Microbiology, Marie Bashir Institute for Emerging Infectious Diseases and Biosecurity, Westmead Clinical School, Sydney Medical School, Westmead Hospital, The University of Sydney, Westmead Institute for Medical Research, Sydney, Australia
| | | | - Angie Gelli
- Department of Pharmacology, University of California, Davis, California, USA
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14
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Patching SG. Recent developments in nucleobase cation symporter-1 (NCS1) family transport proteins from bacteria, archaea, fungi and plants. J Biosci 2018; 43:797-815. [PMID: 30207323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The nucleobase cation symporter-1 (NCS1) family of secondary active transport proteins comprises over 2500 sequenced members from bacteria, archaea, fungi and plants. NCS1 proteins use a proton or sodium gradient to drive inward cellular transport of purine and pyrimidine nucleobases and nucleosides, hydantoins and related compounds. The structural organization, substrate binding residues and molecular mechanism of NCS1 proteins are defined by crystal structures of sodium-coupled hydantoin transporter, Mhp1. Plant proteins are most closely related to bacterial/archaeal proteins and the distinct Fur-type and Fcy-type fungal proteins and plant proteins originated through independent horizontal transfers from prokaryotes. Analyses of 25 experimentally characterized proteins reveal high substrate specificity in bacterial proteins, distinct non-overlapping specificities in Fur-type and Fcy-type fungal proteins and broad specificity in plant proteins. Possible structural explanations are identified for differences in substrate specificity between bacterial proteins, whilst specificities of other proteins cannot be predicted by simple sequence comparisons. Specificity appears to be species specific and determined by combinations of effects dictated by multiple residues in the major substrate binding site and gating domains. This is an exploratory research review of evolutionary relationships, function and structural organization, molecular mechanism and origins of substrate specificity in NCS1 proteins and avenues of future direction.
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Affiliation(s)
- Simon G Patching
- School of Biomedical Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK,
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15
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Patching SG. Recent developments in nucleobase cation symporter-1 (NCS1) family transport proteins from bacteria, archaea, fungi and plants. J Biosci 2018. [DOI: 10.1007/s12038-018-9780-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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16
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Mechanistic Basis of pH-Dependent 5-Flucytosine Resistance in Aspergillus fumigatus. Antimicrob Agents Chemother 2018; 62:AAC.02593-17. [PMID: 29610197 DOI: 10.1128/aac.02593-17] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 03/16/2018] [Indexed: 12/21/2022] Open
Abstract
The antifungal drug 5-flucytosine (5FC), a derivative of the nucleobase cytosine, is licensed for the treatment of fungal diseases; however, it is rarely used as a monotherapeutic to treat Aspergillus infection. Despite being potent against other fungal pathogens, 5FC has limited activity against Aspergillus fumigatus when standard in vitro assays are used to determine susceptibility. However, in modified in vitro assays where the pH is set to pH 5, the activity of 5FC increases significantly. Here we provide evidence that fcyB, a gene that encodes a purine-cytosine permease orthologous to known 5FC importers, is downregulated at pH 7 and is the primary factor responsible for the low efficacy of 5FC at pH 7. We also uncover two transcriptional regulators that are responsible for the repression of fcyB and, consequently, mediators of 5FC resistance, the CCAAT binding complex (CBC) and the pH regulatory protein PacC. We propose that the activity of 5FC might be enhanced by the perturbation of factors that repress fcyB expression, such as PacC or other components of the pH-sensing machinery.
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17
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Simmons KJ, Jackson SM, Brueckner F, Patching SG, Beckstein O, Ivanova E, Geng T, Weyand S, Drew D, Lanigan J, Sharples DJ, Sansom MSP, Iwata S, Fishwick CWG, Johnson AP, Cameron AD, Henderson PJF. Molecular mechanism of ligand recognition by membrane transport protein, Mhp1. EMBO J 2014; 33:1831-44. [PMID: 24952894 PMCID: PMC4195764 DOI: 10.15252/embj.201387557] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The hydantoin transporter Mhp1 is a sodium-coupled secondary active transport protein of the nucleobase-cation-symport family and a member of the widespread 5-helix inverted repeat superfamily of transporters. The structure of Mhp1 was previously solved in three different conformations providing insight into the molecular basis of the alternating access mechanism. Here, we elucidate detailed events of substrate binding, through a combination of crystallography, molecular dynamics, site-directed mutagenesis, biochemical/biophysical assays, and the design and synthesis of novel ligands. We show precisely where 5-substituted hydantoin substrates bind in an extended configuration at the interface of the bundle and hash domains. They are recognised through hydrogen bonds to the hydantoin moiety and the complementarity of the 5-substituent for a hydrophobic pocket in the protein. Furthermore, we describe a novel structure of an intermediate state of the protein with the external thin gate locked open by an inhibitor, 5-(2-naphthylmethyl)-L-hydantoin, which becomes a substrate when leucine 363 is changed to an alanine. We deduce the molecular events that underlie acquisition and transport of a ligand by Mhp1.
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Affiliation(s)
- Katie J Simmons
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - Scott M Jackson
- School of Biomedical Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - Florian Brueckner
- Membrane Protein Laboratory, Diamond Light Source Harwell Science and Innovation Campus, Chilton, Didcot, UK Division of Molecular Biosciences, Membrane Protein Crystallography Group Imperial College, London, UK Rutherford Appleton Laboratory, Research Complex at Harwell, Harwell, Oxford, Didcot, UK
| | - Simon G Patching
- School of Biomedical Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - Oliver Beckstein
- Department of Physics, Arizona State University, Tempe, AZ, USA Department of Biochemistry, University of Oxford, Oxford, UK
| | - Ekaterina Ivanova
- School of Biomedical Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - Tian Geng
- Membrane Protein Laboratory, Diamond Light Source Harwell Science and Innovation Campus, Chilton, Didcot, UK Division of Molecular Biosciences, Membrane Protein Crystallography Group Imperial College, London, UK Rutherford Appleton Laboratory, Research Complex at Harwell, Harwell, Oxford, Didcot, UK
| | - Simone Weyand
- Membrane Protein Laboratory, Diamond Light Source Harwell Science and Innovation Campus, Chilton, Didcot, UK Division of Molecular Biosciences, Membrane Protein Crystallography Group Imperial College, London, UK Rutherford Appleton Laboratory, Research Complex at Harwell, Harwell, Oxford, Didcot, UK
| | - David Drew
- Division of Molecular Biosciences, Membrane Protein Crystallography Group Imperial College, London, UK
| | - Joseph Lanigan
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - David J Sharples
- School of Biomedical Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - So Iwata
- Membrane Protein Laboratory, Diamond Light Source Harwell Science and Innovation Campus, Chilton, Didcot, UK Division of Molecular Biosciences, Membrane Protein Crystallography Group Imperial College, London, UK Rutherford Appleton Laboratory, Research Complex at Harwell, Harwell, Oxford, Didcot, UK
| | - Colin W G Fishwick
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - A Peter Johnson
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - Alexander D Cameron
- Membrane Protein Laboratory, Diamond Light Source Harwell Science and Innovation Campus, Chilton, Didcot, UK Division of Molecular Biosciences, Membrane Protein Crystallography Group Imperial College, London, UK School of Life Sciences, University of Warwick, Coventry, UK
| | - Peter J F Henderson
- School of Biomedical Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
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18
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Calcineurin controls hyphal growth, virulence, and drug tolerance of Candida tropicalis. EUKARYOTIC CELL 2014; 13:844-54. [PMID: 24442892 DOI: 10.1128/ec.00302-13] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Candida tropicalis, a species closely related to Candida albicans, is an emerging fungal pathogen associated with high mortality rates of 40 to 70%. Like C. albicans and Candida dubliniensis, C. tropicalis is able to form germ tubes, pseudohyphae, and hyphae, but the genes involved in hyphal growth machinery and virulence remain unclear in C. tropicalis. Recently, echinocandin- and azole-resistant C. tropicalis isolates have frequently been isolated from various patients around the world, making treatment difficult. However, studies of the C. tropicalis genes involved in drug tolerance are limited. Here, we investigated the roles of calcineurin and its potential target, Crz1, for core stress responses and pathogenesis in C. tropicalis. We demonstrate that calcineurin and Crz1 are required for hyphal growth, micafungin tolerance, and virulence in a murine systemic infection model, while calcineurin but not Crz1 is essential for tolerance of azoles, caspofungin, anidulafungin, and cell wall-perturbing agents, suggesting that calcineurin has both Crz1-dependent and -independent functions in C. tropicalis. In addition, we found that calcineurin and Crz1 have opposite roles in controlling calcium tolerance. Calcineurin serves as a negative regulator, while Crz1 plays a positive role for calcium tolerance in C. tropicalis.
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