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Protein cleavage influences surface protein presentation in Mycoplasma pneumoniae. Sci Rep 2021; 11:6743. [PMID: 33762641 PMCID: PMC7990945 DOI: 10.1038/s41598-021-86217-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 02/23/2021] [Indexed: 01/31/2023] Open
Abstract
Mycoplasma pneumoniae is a significant cause of pneumonia and post infection sequelae affecting organ sites distant to the respiratory tract are common. It is also a model organism where extensive 'omics' studies have been conducted to gain insight into how minimal genome self-replicating organisms function. An N-terminome study undertaken here identified 4898 unique N-terminal peptides that mapped to 391 (56%) predicted M. pneumoniae proteins. True N-terminal sequences beginning with the initiating methionine (iMet) residue from the predicted Open Reading Frame (ORF) were identified for 163 proteins. Notably, almost half (317; 46%) of the ORFS derived from M. pneumoniae strain M129 are post-translationally modified, presumably by proteolytic processing, because dimethyl labelled neo-N-termini were characterised that mapped beyond the predicted N-terminus. An analysis of the N-terminome describes endoproteolytic processing events predominately targeting tryptic-like sites, though cleavages at negatively charged residues in P1' (D and E) with lysine or serine/alanine in P2' and P3' positions also occurred frequently. Surfaceome studies identified 160 proteins (23% of the proteome) to be exposed on the extracellular surface of M. pneumoniae. The two orthogonal methodologies used to characterise the surfaceome each identified the same 116 proteins, a 72% (116/160) overlap. Apart from lipoproteins, transporters, and adhesins, 93/160 (58%) of the surface proteins lack signal peptides and have well characterised, canonical functions in the cell. Of the 160 surface proteins identified, 134 were also targets of endo-proteolytic processing. These processing events are likely to have profound implications for how the host immune system recognises and responds to M. pneumoniae.
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Harne S, Duret S, Pande V, Bapat M, Béven L, Gayathri P. MreB5 Is a Determinant of Rod-to-Helical Transition in the Cell-Wall-less Bacterium Spiroplasma. Curr Biol 2020; 30:4753-4762.e7. [PMID: 32976813 DOI: 10.1016/j.cub.2020.08.093] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 08/05/2020] [Accepted: 08/26/2020] [Indexed: 12/22/2022]
Abstract
In most rod-shaped bacteria, the spatial coordination of cell wall synthesis machinery by MreBs is the main theme for shape determination and maintenance in cell-walled bacteria [1-9]. However, how rod or spiral shapes are achieved and maintained in cell-wall-less bacteria is currently unknown. Spiroplasma, a helical Mollicute that lacks cell wall synthesis genes, encodes five MreB paralogs and a unique cytoskeletal protein fibril [10, 11]. Here, we show that MreB5, one of the five MreB paralogs, contributes to cell elongation and is essential for the transition from rod-to-helical shape in Spiroplasma. Comparative genomic and proteomic characterization of a helical and motile wild-type Spiroplasma strain and a non-helical, non-motile natural variant helped delineate the specific roles of MreB5. Moreover, complementation of the non-helical strain with MreB5 restored its helical shape and motility by a kink-based mechanism described for Spiroplasma [12]. Earlier studies had proposed that length changes in fibril filaments are responsible for the change in handedness of the helical cell and kink propagation during motility [13]. Through structural and biochemical characterization, we identify that MreB5 exists as antiparallel double protofilaments that interact with fibril and the membrane, and thus potentially assists in kink propagation. In summary, our study provides direct experimental evidence for MreB in maintaining cell length, helical shape, and motility-revealing the role of MreB in sculpting the cell in the absence of a cell wall.
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Affiliation(s)
- Shrikant Harne
- Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune 411008, India
| | - Sybille Duret
- INRAE, University of Bordeaux, UMR 1332 BFP, Villenave d'Ornon, Bordeaux, France
| | - Vani Pande
- Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune 411008, India
| | - Mrinmayee Bapat
- Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune 411008, India
| | - Laure Béven
- INRAE, University of Bordeaux, UMR 1332 BFP, Villenave d'Ornon, Bordeaux, France.
| | - Pananghat Gayathri
- Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune 411008, India.
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Huang W, Reyes-Caldas P, Mann M, Seifbarghi S, Kahn A, Almeida RPP, Béven L, Heck M, Hogenhout SA, Coaker G. Bacterial Vector-Borne Plant Diseases: Unanswered Questions and Future Directions. MOLECULAR PLANT 2020; 13:1379-1393. [PMID: 32835885 PMCID: PMC7769051 DOI: 10.1016/j.molp.2020.08.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/18/2020] [Accepted: 08/18/2020] [Indexed: 06/01/2023]
Abstract
Vector-borne plant diseases have significant ecological and economic impacts, affecting farm profitability and forest composition throughout the world. Bacterial vector-borne pathogens have evolved sophisticated strategies to interact with their hemipteran insect vectors and plant hosts. These pathogens reside in plant vascular tissue, and their study represents an excellent opportunity to uncover novel biological mechanisms regulating intracellular pathogenesis and to contribute to the control of some of the world's most invasive emerging diseases. In this perspective, we highlight recent advances and major unanswered questions in the realm of bacterial vector-borne disease, focusing on liberibacters, phytoplasmas, spiroplasmas, and Xylella fastidiosa.
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Affiliation(s)
- Weijie Huang
- Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Paola Reyes-Caldas
- Department of Plant Pathology, University of California, Davis, CA, 95616, USA
| | - Marina Mann
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
| | - Shirin Seifbarghi
- Department of Plant Pathology, University of California, Davis, CA, 95616, USA
| | - Alexandra Kahn
- Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720, USA
| | - Rodrigo P P Almeida
- Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720, USA
| | - Laure Béven
- UMR 1332 Biologie du Fruit et Pathologie, Univ. Bordeaux, INRAE, Villenave d'Ornon 33882 France
| | - Michelle Heck
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA; Boyce Thompson Institute, Ithaca, NY 14853, USA; Emerging Pests and Pathogens Research Unit, Robert W. Holley Center, USDA ARS, Ithaca, NY 14853, USA
| | - Saskia A Hogenhout
- Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK; School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Gitta Coaker
- Department of Plant Pathology, University of California, Davis, CA, 95616, USA.
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Widjaja M, Berry IJ, Jarocki VM, Padula MP, Dumke R, Djordjevic SP. Cell surface processing of the P1 adhesin of Mycoplasma pneumoniae identifies novel domains that bind host molecules. Sci Rep 2020; 10:6384. [PMID: 32286369 PMCID: PMC7156367 DOI: 10.1038/s41598-020-63136-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 03/20/2020] [Indexed: 02/07/2023] Open
Abstract
Mycoplasma pneumoniae is a genome reduced pathogen and causative agent of community acquired pneumonia. The major cellular adhesin, P1, localises to the tip of the attachment organelle forming a complex with P40 and P90, two cleavage fragments derived by processing Mpn142, and other molecules with adhesive and mobility functions. LC-MS/MS analysis of M. pneumoniae M129 proteins derived from whole cell lysates and eluents from affinity matrices coupled with chemically diverse host molecules identified 22 proteoforms of P1. Terminomics was used to characterise 17 cleavage events many of which were independently verified by the identification of semi-tryptic peptides in our proteome studies and by immunoblotting. One cleavage event released 1597TSAAKPGAPRPPVPPKPGAPKPPVQPPKKPA1627 from the C-terminus of P1 and this peptide was shown to bind to a range of host molecules. A smaller synthetic peptide comprising the C-terminal 15 amino acids, 1613PGAPKPPVQPPKKPA1627, selectively bound cytoskeletal intermediate filament proteins cytokeratin 7, cytokeratin 8, cytokeratin 18, and vimentin from a native A549 cell lysate. Collectively, our data suggests that ectodomain shedding occurs on the surface of M. pneumoniae where it may alter the functional diversity of P1, Mpn142 and other surface proteins such as elongation factor Tu via a mechanism similar to that described in Mycoplasma hyopneumoniae.
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Affiliation(s)
- Michael Widjaja
- The ithree institute, University of Technology Sydney, PO Box 123, Broadway, NSW, 2007, Australia
| | - Iain James Berry
- The ithree institute, University of Technology Sydney, PO Box 123, Broadway, NSW, 2007, Australia
| | - Veronica Maria Jarocki
- The ithree institute, University of Technology Sydney, PO Box 123, Broadway, NSW, 2007, Australia
| | - Matthew Paul Padula
- Proteomics Core Facility and School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, NSW, 2007, Australia
| | - Roger Dumke
- Technische Universität Dresden, Medizinische Fakultät Carl Gustav Carus, Institut für Medizinische Mikrobiologie und Hygiene, Fetscherstrasse 74, 01307, Dresden, Germany
| | - Steven Philip Djordjevic
- The ithree institute, University of Technology Sydney, PO Box 123, Broadway, NSW, 2007, Australia. .,Proteomics Core Facility and School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, NSW, 2007, Australia.
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Proteases as Secreted Exoproteins in Mycoplasmas from Ruminant Lungs and Their Impact on Surface-Exposed Proteins. Appl Environ Microbiol 2019; 85:AEM.01439-19. [PMID: 31540994 DOI: 10.1128/aem.01439-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 09/10/2019] [Indexed: 12/29/2022] Open
Abstract
Many mycoplasma species are isolated from the ruminant lungs as either saprophytes or true pathogens. These wall-less bacteria possess a minimal genome and reduced metabolic capabilities. Accordingly, they rely heavily on their hosts for the supply of essential metabolites and, notably, peptides. Seven of 13 ruminant lung-associated Mycoplasma (sub)species were shown to possess caseinolytic activity when grown in rich media and assessed with a quantitative fluorescence test. For some species, this activity was detected in spent medium, an indication that proteases were secreted outside the mycoplasma cells. To identify these proteases, we incubated concentrated washed cell pellets in a defined medium and analyzed the supernatants by tandem mass spectrometry. Secreted-protease activity was detected mostly in the species belonging to the Mycoplasma mycoides cluster (MMC) and, to a lesser extent, in Mycoplasma bovirhinis Analyzing a Mycoplasma mycoides subsp. capri strain, chosen as a model, we identified 35 expressed proteases among 55 predicted coding genes, of which 5 were preferentially found in the supernatant. Serine protease S41, acquired by horizontal gene transfer, was responsible for the caseinolytic activity, as demonstrated by zymography and mutant analysis. In an M. capricolum mutant, inactivation of the S41 protease resulted in marked modification of the expression or secretion of 17 predicted surface-exposed proteins. This is an indication that the S41 protease could have a role in posttranslational cleavage of surface-exposed proteins and ectodomain shedding, whose physiological impacts still need to be explored.IMPORTANCE Few studies pertaining to proteases in ruminant mycoplasmas have been reported. Here, we focus on proteases that are secreted outside the mycoplasma cell using a mass spectrometry approach. The most striking result is the identification, within the Mycoplasma mycoides cluster, of a serine protease that is exclusively detected outside the mycoplasma cells and is responsible for casein digestion. This protease may also be involved in the posttranslational processing of surface proteins, as suggested by analysis of mutants showing a marked reduction in the secretion of extracellular proteins. By analogy, this finding may help increase understanding of the mechanisms underlying this ectodomain shedding in other mycoplasma species. The gene encoding this protease is likely to have been acquired via horizontal gene transfer from Gram-positive bacteria and sortase-associated surface proteases. Whether this protease and the associated ectodomain shedding are related to virulence has yet to be ascertained.
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Immunofluorescence Assay to Study Early Events of Vector Salivary Gland Colonization by Phytoplasmas. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2019; 1875:307-317. [PMID: 30362013 DOI: 10.1007/978-1-4939-8837-2_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
To visualize phytoplasmas at early stages of vector infection, an immunofluorescence assay was developed. The chapter provides experimental details on dissection of salivary glands, incubation of the dissected organs with phytoplasma suspension, fixation, embedding, sectioning, labeling, and final visualization with confocal microscopy. All the procedure will be described for the leafhopper Euscelidius variegatus, natural vector of "Candidatus phytoplasma asteris" and laboratory vector of Flavescence dorée phytoplasma.
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