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Salogiannis J, Christensen JR, Songster LD, Aguilar-Maldonado A, Shukla N, Reck-Peterson SL. PxdA interacts with the DipA phosphatase to regulate peroxisome hitchhiking on early endosomes. Mol Biol Cell 2021; 32:492-503. [PMID: 33476181 PMCID: PMC8101442 DOI: 10.1091/mbc.e20-08-0559] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
In canonical microtubule-based transport, adaptor proteins link cargoes to dynein and kinesin motors. Recently, an alternative mode of transport known as “hitchhiking” was discovered, where cargoes achieve motility by hitching a ride on already-motile cargoes, rather than attaching to a motor protein. Hitchhiking has been best studied in two filamentous fungi, Aspergillus nidulans and Ustilago maydis. In U. maydis, ribonucleoprotein complexes, peroxisomes, lipid droplets (LDs), and endoplasmic reticulum hitchhike on early endosomes (EEs). In A. nidulans, peroxisomes hitchhike using a putative molecular linker, peroxisome distribution mutant A (PxdA), which associates with EEs. However, whether other organelles use PxdA to hitchhike on EEs is unclear, as are the molecular mechanisms that regulate hitchhiking. Here we find that the proper distribution of LDs, mitochondria, and preautophagosomes do not require PxdA, suggesting that PxdA is a peroxisome-specific molecular linker. We identify two new pxdA alleles, including a point mutation (R2044P) that disrupts PxdA’s ability to associate with EEs and reduces peroxisome movement. We also identify a novel regulator of peroxisome hitchhiking, the phosphatase DipA. DipA colocalizes with EEs and its association with EEs relies on PxdA. Together, our data suggest that PxdA and the DipA phosphatase are specific regulators of peroxisome hitchhiking on EEs.
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Affiliation(s)
- John Salogiannis
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093.,Howard Hughes Medical Institute, Chevy Chase, MD 20815
| | - Jenna R Christensen
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Livia D Songster
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093.,Division of Biological Sciences, Cell and Developmental Biology Section, University of California, San Diego, La Jolla, CA 92093
| | - Adriana Aguilar-Maldonado
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Nandini Shukla
- The Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 043210.,Department of Molecular Genetics, The Ohio State University, Columbus, OH 043210
| | - Samara L Reck-Peterson
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093.,Division of Biological Sciences, Cell and Developmental Biology Section, University of California, San Diego, La Jolla, CA 92093.,Howard Hughes Medical Institute, Chevy Chase, MD 20815
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Dimou S, Kourkoulou A, Amillis S, Percudani R, Diallinas G. The peroxisomal SspA protein is redundant for purine utilization but essential for peroxisome localization in septal pores in Aspergillus nidulans. Fungal Genet Biol 2019; 132:103259. [PMID: 31394175 DOI: 10.1016/j.fgb.2019.103259] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 07/22/2019] [Accepted: 07/25/2019] [Indexed: 10/26/2022]
Abstract
In an in silico search for correlated gene loss with fungal peroxisomal uric acid oxidase (UOX), we identified PMP22-like proteins, some of which function as promiscuous channels in organellar membranes. To investigate whether PMP22 channels have a role in peroxisomal uric acid transport and catabolism, we functionally analyzed the closest homologue in Aspergillus nidulans, named SspA. We confirmed that SspA is a peroxisomal membrane protein that co-localizes significantly with PTS1-tagged mRFP, UOX or HexA, the latter considered a protein of Woronin bodies (WB), organelles originating from peroxisomes that dynamically plug septal pores in ascomycetes. Our results suggest that in A. nidulans, unlike some other ascomycetes, there is no strict protein segregation of peroxisomal and WB-specific proteins. Importantly, genetic deletion of sspA, but not of hexA, led to lack of peroxisomal localization at septal pores, suggesting that SspA is a key factor for septal pore functioning. Additionally, ΔsspA resulted in increased sensitivity to oxidative stress, apparently as a consequence of not only the inability to plug septal pores, but also a recorded reduction in peroxisome biogenesis. However, deleting sspA had no effect on uric acid or purine utilization, as we hypothesized, a result also in line with the observation that expression of SspA was not affected by regulatory mutants and conditions known to control purine catabolic enzymes. Our results are discussed within the framework of previous studies of SspA homologues in other fungi, as well as, the observed gene losses of PMP22 and peroxisomal uric acid oxidase.
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Affiliation(s)
- Sofia Dimou
- Department of Biology, National and Kapodistrian University of Athens, Panepistimioupolis, 15784 Athens, Greece
| | - Anezia Kourkoulou
- Department of Biology, National and Kapodistrian University of Athens, Panepistimioupolis, 15784 Athens, Greece
| | - Sotiris Amillis
- Department of Biology, National and Kapodistrian University of Athens, Panepistimioupolis, 15784 Athens, Greece
| | - Riccardo Percudani
- Department of Chemistry, Life Sciences, and Environmental Sustainability, University of Parma, 43124 Parma, Italy
| | - George Diallinas
- Department of Biology, National and Kapodistrian University of Athens, Panepistimioupolis, 15784 Athens, Greece.
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Abstract
Peroxisomes are key metabolic organelles, which contribute to cellular lipid metabolism, e.g. the β-oxidation of fatty acids and the synthesis of myelin sheath lipids, as well as cellular redox balance. Peroxisomal dysfunction has been linked to severe metabolic disorders in man, but peroxisomes are now also recognized as protective organelles with a wider significance in human health and potential impact on a large number of globally important human diseases such as neurodegeneration, obesity, cancer, and age-related disorders. Therefore, the interest in peroxisomes and their physiological functions has significantly increased in recent years. In this review, we intend to highlight recent discoveries, advancements and trends in peroxisome research, and present an update as well as a continuation of two former review articles addressing the unsolved mysteries of this astonishing organelle. We summarize novel findings on the biological functions of peroxisomes, their biogenesis, formation, membrane dynamics and division, as well as on peroxisome-organelle contacts and cooperation. Furthermore, novel peroxisomal proteins and machineries at the peroxisomal membrane are discussed. Finally, we address recent findings on the role of peroxisomes in the brain, in neurological disorders, and in the development of cancer.
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Affiliation(s)
- Markus Islinger
- Institute of Neuroanatomy, Center for Biomedicine and Medical Technology Mannheim, Medical Faculty Manheim, University of Heidelberg, 68167, Mannheim, Germany
| | - Alfred Voelkl
- Institute for Anatomy and Cell Biology, University of Heidelberg, 69120, Heidelberg, Germany
| | - H Dariush Fahimi
- Institute for Anatomy and Cell Biology, University of Heidelberg, 69120, Heidelberg, Germany
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Krombach S, Reissmann S, Kreibich S, Bochen F, Kahmann R. Virulence function of the Ustilago maydis sterol carrier protein 2. THE NEW PHYTOLOGIST 2018; 220:553-566. [PMID: 29897130 DOI: 10.1111/nph.15268] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 05/14/2018] [Indexed: 05/06/2023]
Abstract
The peroxisomal sterol carrier protein 2 (Scp2) of the biotrophic maize pathogen Ustilago maydis was detected in apoplastic fluid, suggesting that it might function as a secreted effector protein. Here we analyze the role of the scp2 gene during plant colonization. We used reverse genetics approaches to delete the scp2 gene, determined stress sensitivity and fatty acid utilization of mutants, demonstrated secretion of Scp2, used quantitative reverse transcription polymerase chain reaction for expression analysis and expressed GFP-Scp2 fusion proteins for protein localization. scp2 mutants were strongly attenuated in virulence and this defect manifested itself during penetration. Scp2 localized to peroxisomes and peroxisomal targeting was necessary for its virulence function. Deletion of scp2 in U. maydis interfered neither with growth nor with peroxisomal β-oxidation. Conventionally secreted Scp2 protein could not rescue the virulence defect. scp2 mutants displayed an altered localization of peroxisomes. Our results show a virulence function for Scp2 during penetration that is probably carried out by Scp2 in peroxisomes. We speculate that Scp2 affects the lipid composition of membranes and in this way ensures the even cellular distribution of peroxisomes.
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Affiliation(s)
- Sina Krombach
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 10, 35043, Marburg, Germany
| | - Stefanie Reissmann
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 10, 35043, Marburg, Germany
| | - Saskia Kreibich
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 10, 35043, Marburg, Germany
| | - Florian Bochen
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 10, 35043, Marburg, Germany
| | - Regine Kahmann
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 10, 35043, Marburg, Germany
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Hanano A, Alkara M, Almousally I, Shaban M, Rahman F, Hassan M, Murphy DJ. The Peroxygenase Activity of the Aspergillus flavus Caleosin, AfPXG, Modulates the Biosynthesis of Aflatoxins and Their Trafficking and Extracellular Secretion via Lipid Droplets. Front Microbiol 2018; 9:158. [PMID: 29467750 PMCID: PMC5808235 DOI: 10.3389/fmicb.2018.00158] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 01/23/2018] [Indexed: 11/29/2022] Open
Abstract
Aflatoxins (AF) are highly detrimental to human and animal health. We recently demonstrated that the Aspergillus flavus caleosin, AfPXG, had peroxygenase activity and mediated fungal development and AF accumulation. We now report the characterization of an AfPXG-deficient line using reference strain NRRL3357. The resulting fungal phenotype included a severe decrease in mycelium growth, failure to sporulate, and reduced AF production. Increasing cellular oxidative status by administration of hydrogen peroxide and cumene hydroperoxide did not restore the AfPXG-deficient phenotype, which suggests that AfPXG-deficiency is not directly related to oxidative stress. To investigate possible alternative roles of AfPXG, a gain of function approach was used to overexpress AfPXG, with the reporter gene Gfp, in an AfPXG-deficient line, termed AfPXG+ . The resulting phenotype included elevated numbers of stable lipid droplets (LDs) plus enhanced AF production. Highly purified LDs from AfPXG+ cultures sequestered AF and this ability was positively correlated with overall LD number. Site-specific mutagenesis of AfPXG to delete Histidine 85 (AfPXGHis85), a residue essential for its catalytic activity, or deletion of the putative LD targeting domain (AfPXGD126-140), showed that AfPXG-peroxygenase activity was required for AF biosynthesis and that integration of AF into LDs was required for their export via a LD-dependent pathway. Ectopic expression in fungal cells of the plant LD-associated protein, oleosin, also resulted in both additional LD accumulation and enhanced AF secretion. These results suggest that both fungal LDs and their associated caleosin proteins are intimately involved in the biosynthesis, trafficking, and secretion of AF.
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Affiliation(s)
- Abdulsamie Hanano
- Department of Molecular Biology and Biotechnology, Atomic Energy Commission of Syria, Damascus, Syria
| | - Mari Alkara
- Department of Molecular Biology and Biotechnology, Atomic Energy Commission of Syria, Damascus, Syria
| | - Ibrahem Almousally
- Department of Molecular Biology and Biotechnology, Atomic Energy Commission of Syria, Damascus, Syria
| | - Mouhnad Shaban
- Department of Molecular Biology and Biotechnology, Atomic Energy Commission of Syria, Damascus, Syria
| | - Farzana Rahman
- Genomics and Computational Biology Research Group, University of South Wales, Pontypridd, United Kingdom
| | - Mehedi Hassan
- Genomics and Computational Biology Research Group, University of South Wales, Pontypridd, United Kingdom
| | - Denis J. Murphy
- Genomics and Computational Biology Research Group, University of South Wales, Pontypridd, United Kingdom
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Spatial organization of organelles in fungi: Insights from mathematical modelling. Fungal Genet Biol 2017; 103:55-59. [PMID: 28351675 PMCID: PMC5476193 DOI: 10.1016/j.fgb.2017.03.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 03/15/2017] [Accepted: 03/22/2017] [Indexed: 01/03/2023]
Abstract
Modelling of dynein motility reveals a stochastic role in dynein comet formation. Modelling helps to elucidate mechanisms in spatial organization of early endosomes. A combination of diffusion and directed motion distributes ribosomes and peroxisomes.
Mathematical modelling in cellular systems aims to describe biological processes in a quantitative manner. Most accurate modelling is based on robust experimental data. Here we review recent progress in the theoretical description of motor behaviour, early endosome motility, ribosome distribution and peroxisome transport in the fungal model system Ustilago maydis and illustrate the power of modelling in our quest to understand molecular details and cellular roles of membrane trafficking in filamentous fungi.
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