1
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Kato S, Tahara YO, Nishimura Y, Uematsu K, Arai T, Nakane D, Ihara A, Nishizaka T, Iwasaki W, Itoh T, Miyata M, Ohkuma M. Cell surface architecture of the cultivated DPANN archaeon Nanobdella aerobiophila. J Bacteriol 2024; 206:e0035123. [PMID: 38289045 PMCID: PMC10882981 DOI: 10.1128/jb.00351-23] [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: 10/27/2023] [Accepted: 12/22/2023] [Indexed: 02/23/2024] Open
Abstract
The DPANN archaeal clade includes obligately ectosymbiotic species. Their cell surfaces potentially play an important role in the symbiotic interaction between the ectosymbionts and their hosts. However, little is known about the mechanism of ectosymbiosis. Here, we show cell surface structures of the cultivated DPANN archaeon Nanobdella aerobiophila strain MJ1T and its host Metallosphaera sedula strain MJ1HA, using a variety of electron microscopy techniques, i.e., negative-staining transmission electron microscopy, quick-freeze deep-etch TEM, and 3D electron tomography. The thickness, unit size, and lattice symmetry of the S-layer of strain MJ1T were different from those of the host archaeon strain MJ1HA. Genomic and transcriptomic analyses highlighted the most highly expressed MJ1T gene for a putative S-layer protein with multiple glycosylation sites and immunoglobulin-like folds, which has no sequence homology to known S-layer proteins. In addition, genes for putative pectin lyase- or lectin-like extracellular proteins, which are potentially involved in symbiotic interaction, were found in the MJ1T genome based on in silico 3D protein structure prediction. Live cell imaging at the optimum growth temperature of 65°C indicated that cell complexes of strains MJ1T and MJ1HA were motile, but sole MJ1T cells were not. Taken together, we propose a model of the symbiotic interaction and cell cycle of Nanobdella aerobiophila.IMPORTANCEDPANN archaea are widely distributed in a variety of natural and artificial environments and may play a considerable role in the microbial ecosystem. All of the cultivated DPANN archaea so far need host organisms for their growth, i.e., obligately ectosymbiotic. However, the mechanism of the ectosymbiosis by DPANN archaea is largely unknown. To this end, we performed a comprehensive analysis of the cultivated DPANN archaeon, Nanobdella aerobiophila, using electron microscopy, live cell imaging, transcriptomics, and genomics, including 3D protein structure prediction. Based on the results, we propose a reasonable model of the symbiotic interaction and cell cycle of Nanobdella aerobiophila, which will enhance our understanding of the enigmatic physiology and ecological significance of DPANN archaea.
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Affiliation(s)
- Shingo Kato
- Japan Collection of Microorganisms (JCM), RIKEN BioResource Research Center, Tsukuba, Ibaraki, Japan
| | - Yuhei O. Tahara
- Graduate School of Science, Osaka Metropolitan University, Osaka, Japan
| | - Yuki Nishimura
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, Japan
| | | | | | - Daisuke Nakane
- Department of Physics, Gakushuin University, Tokyo, Japan
| | - Ayaka Ihara
- Department of Physics, Gakushuin University, Tokyo, Japan
| | | | - Wataru Iwasaki
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, Japan
| | - Takashi Itoh
- Japan Collection of Microorganisms (JCM), RIKEN BioResource Research Center, Tsukuba, Ibaraki, Japan
| | - Makoto Miyata
- Graduate School of Science, Osaka Metropolitan University, Osaka, Japan
| | - Moriya Ohkuma
- Japan Collection of Microorganisms (JCM), RIKEN BioResource Research Center, Tsukuba, Ibaraki, Japan
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2
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De Castro RE, Giménez MI, Cerletti M, Paggi RA, Costa MI. Proteolysis at the Archaeal Membrane: Advances on the Biological Function and Natural Targets of Membrane-Localized Proteases in Haloferax volcanii. Front Microbiol 2022; 13:940865. [PMID: 35814708 PMCID: PMC9263693 DOI: 10.3389/fmicb.2022.940865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 06/06/2022] [Indexed: 11/23/2022] Open
Abstract
Proteolysis plays a fundamental role in many processes that occur within the cellular membrane including protein quality control, protein export, cell signaling, biogenesis of the cell envelope among others. Archaea are a distinct and physiologically diverse group of prokaryotes found in all kinds of habitats, from the human and plant microbiomes to those with extreme salt concentration, pH and/or temperatures. Thus, these organisms provide an excellent opportunity to extend our current understanding on the biological functions that proteases exert in cell physiology including the adaptation to hostile environments. This revision describes the advances that were made on archaeal membrane proteases with regard to their biological function and potential natural targets focusing on the model haloarchaeon Haloferax volcanii.
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3
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Pei D, Dalbey RE. Membrane Translocation of Folded Proteins. J Biol Chem 2022; 298:102107. [PMID: 35671825 PMCID: PMC9251779 DOI: 10.1016/j.jbc.2022.102107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Revised: 05/31/2022] [Accepted: 06/01/2022] [Indexed: 12/01/2022] Open
Abstract
An ever-increasing number of proteins have been shown to translocate across various membranes of bacterial as well as eukaryotic cells in their folded states as a part of physiological and/or pathophysiological processes. Herein we provide an overview of the systems/processes that are established or likely to involve the membrane translocation of folded proteins, such as protein export by the twin-arginine translocation (TAT) system in bacteria and chloroplasts, unconventional protein secretion (UPS) and protein import into the peroxisome in eukaryotes, and the cytosolic entry of proteins (e.g., bacterial toxins) and viruses into eukaryotes. We also discuss the various mechanistic models that have previously been proposed for the membrane translocation of folded proteins including pore/channel formation, local membrane disruption, membrane thinning, and transport by membrane vesicles. Finally, we introduce a newly discovered vesicular transport mechanism, vesicle budding and collapse (VBC), and present evidence that VBC may represent a unifying mechanism that drives some (and potentially all) of folded protein translocation processes.
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Affiliation(s)
- Dehua Pei
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12(th) Avenue, Columbus, OH 43210.
| | - Ross E Dalbey
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12(th) Avenue, Columbus, OH 43210.
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4
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Yu X, Conyne M, Lake MR, Walter KA, Min J. In silico high throughput mutagenesis and screening of signal peptides to mitigate N-terminal heterogeneity of recombinant monoclonal antibodies. MAbs 2022; 14:2044977. [PMID: 35275041 PMCID: PMC8920188 DOI: 10.1080/19420862.2022.2044977] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
N-terminal heterogeneity resulting from non-uniform signal peptide (SP) cleavage can potentially affect biologics property attributes and result in extended product development timelines. Few studies are available on engineering SPs systematically to address miscleavage issues. Herein, we developed a novel high throughput computational pipeline capable of generating millions of SP mutant sequences that uses the SignalP 5.0 deep learning model to predict which of these mutants are likely to alleviate the N-terminal miscleavage in antibodies. We optimized the parameters to target mutating one or two amino acids at the C-terminus of 84 unique SPs, exhausting all theoretically possible combinations and resulting in a library of 296,077 unique wildtype and mutant signal peptides for in silico screening of each antibody. We applied this method to five antibodies against different targets, with various extent of miscleavage (2.3% to 100%) on their Lambda light chains. In each case, multiple SP mutants were generated, with miscleavage reduced to a non-detectable level and titers comparable with or better than that of the original SPs. Pairwise mutational analysis using an in silico library enriched with high-scoring mutants revealed patterns of amino acids at the C-terminus of SPs, providing insights beyond the “Heijne rule”. To our knowledge, no similar approach that combines high throughput in silico mutagenesis and screening with SP cleavage prediction has been reported in the literature. This method can be applied to both the light chain and heavy chain of antibodies, regardless of their initial extent of miscleavage, provides optimized solutions for individual cases, and facilitates the development of antibody therapeutics. Abbreviations: Aa, amino acids; CHO, Chinese hamster ovary; CNN, convolutional neural network; CSscore, cleavage site score; CSV, comma-separated values; HC, heavy chain; HEK, human embryonic kidney; HPLC, high-performance liquid chromatography; IgG, immunoglobulin G; IGLV, immunoglobulin G Lambda variable; LC, light chain; LCMS, liquid chromatography–mass spectrometry; MS, mass spectrometry; PCR, polymerase chain reaction; PBS, phosphate-buffered saline; PEI, polyethylenimine; SP, signal peptide; SPase, signal peptidase; TCEP, tris(2-carboxyethyl) phosphine; TOF, time-of-flight.
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Affiliation(s)
- Xin Yu
- Drug Discovery Science and Technology, AbbVie Bioresearch Center, Worcester, MA, US
| | - Merlinda Conyne
- Drug Discovery Science and Technology, AbbVie Inc, North Chicago, IL, US
| | - Marc R Lake
- Drug Discovery Science and Technology, AbbVie Inc, North Chicago, IL, US
| | - Karl A Walter
- Drug Discovery Science and Technology, AbbVie Inc, North Chicago, IL, US
| | - Jing Min
- Drug Discovery Science and Technology, AbbVie Bioresearch Center, Worcester, MA, US
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5
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Singhal N, Garg A, Singh N, Gulati P, Kumar M, Goel M. Efficacy of signal peptide predictors in identifying signal peptides in the experimental secretome of Picrophilous torridus, a thermoacidophilic archaeon. PLoS One 2021; 16:e0255826. [PMID: 34358261 PMCID: PMC8345856 DOI: 10.1371/journal.pone.0255826] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 07/25/2021] [Indexed: 11/28/2022] Open
Abstract
Secretory proteins are important for microbial adaptation and survival in a particular environment. Till date, experimental secretomes have been reported for a few archaea. In this study, we have identified the experimental secretome of Picrophilous torridus and evaluated the efficacy of various signal peptide predictors (SPPs) in identifying signal peptides (SPs) in its experimental secretome. Liquid chromatography mass spectrometric (LC MS) analysis was performed for three independent P. torridus secretome samples and only those proteins which were common in the three experiments were selected for further analysis. Thus, 30 proteins were finally included in this study. Of these, 10 proteins were identified as hypothetical/uncharacterized proteins. Gene Ontology, KEGG and STRING analyses revealed that majority of the sercreted proteins and/or their interacting partners were involved in different metabolic pathways. Also, a few proteins like malate dehydrogenase (Q6L0C3) were multi-functional involved in different metabolic pathways like carbon metabolism, microbial metabolism in diverse environments, biosynthesis of antibiotics, etc. Multi-functionality of the secreted proteins reflects an important aspect of thermoacidophilic adaptation of P. torridus which has the smallest genome (1.5 Mbp) among nonparasitic aerobic microbes. SPPs like, PRED-SIGNAL, SignalP 5.0, PRED-TAT and LipoP 1.0 identified SPs in only a few secreted proteins. This suggests that either these SPPs were insufficient, or N-terminal SPs were absent in majority of the secreted proteins, or there might be alternative mechanisms of protein translocation in P. torridus.
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Affiliation(s)
- Neelja Singhal
- Department of Biophysics, University of Delhi South Campus, New Delhi, India
| | - Anjali Garg
- Department of Biophysics, University of Delhi South Campus, New Delhi, India
| | - Nirpendra Singh
- Regional Center for Biotechnology, NCR-Biotech Science Cluster, Faridabad, India
| | - Pallavi Gulati
- Department of Microbiology, University of Delhi South Campus, New Delhi, India
| | - Manish Kumar
- Department of Biophysics, University of Delhi South Campus, New Delhi, India
| | - Manisha Goel
- Department of Biophysics, University of Delhi South Campus, New Delhi, India
- * E-mail:
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6
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Functional compartmentalization and metabolic separation in a prokaryotic cell. Proc Natl Acad Sci U S A 2021; 118:2022114118. [PMID: 34161262 DOI: 10.1073/pnas.2022114118] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The prokaryotic cell is traditionally seen as a "bag of enzymes," yet its organization is much more complex than in this simplified view. By now, various microcompartments encapsulating metabolic enzymes or pathways are known for Bacteria These microcompartments are usually small, encapsulating and concentrating only a few enzymes, thus protecting the cell from toxic intermediates or preventing unwanted side reactions. The hyperthermophilic, strictly anaerobic Crenarchaeon Ignicoccus hospitalis is an extraordinary organism possessing two membranes, an inner and an energized outer membrane. The outer membrane (termed here outer cytoplasmic membrane) harbors enzymes involved in proton gradient generation and ATP synthesis. These two membranes are separated by an intermembrane compartment, whose function is unknown. Major information processes like DNA replication, RNA synthesis, and protein biosynthesis are located inside the "cytoplasm" or central cytoplasmic compartment. Here, we show by immunogold labeling of ultrathin sections that enzymes involved in autotrophic CO2 assimilation are located in the intermembrane compartment that we name (now) a peripheric cytoplasmic compartment. This separation may protect DNA and RNA from reactive aldehydes arising in the I. hospitalis carbon metabolism. This compartmentalization of metabolic pathways and information processes is unprecedented in the prokaryotic world, representing a unique example of spatiofunctional compartmentalization in the second domain of life.
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Abstract
The past several decades have witnessed tremendous growth in the protein targeting, transport and translocation field. Major advances were made during this time period. Now the molecular details of the targeting factors, receptors and the membrane channels that were envisioned in Blobel's Signal Hypothesis in the 1970s have been revealed by powerful structural methods. It is evident that there is a myriad of cytosolic and membrane associated systems that accurately sort and target newly synthesized proteins to their correct membrane translocases for membrane insertion or protein translocation. Here we will describe the common principles for protein transport in prokaryotes and eukaryotes.
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8
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Ghosh D, Boral D, Vankudoth KR, Ramasamy S. Analysis of haloarchaeal twin-arginine translocase pathway reveals the diversity of the machineries. Heliyon 2019; 5:e01587. [PMID: 31193317 PMCID: PMC6525301 DOI: 10.1016/j.heliyon.2019.e01587] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 03/23/2019] [Accepted: 04/24/2019] [Indexed: 01/10/2023] Open
Abstract
The twin-arginine translocase (Tat) pathway transports folded proteins across the plasma membrane and plays a critical role in protein transport in haloarchaea. Computational analysis and previous experimental evidence suggested that the Tat pathway transports almost the entire secretome in haloarchaea. The TatC, receptor component of this pathway shows greater variation in membrane topology in haloarchaea than in other organisms. The presence of a unique fourteen-transmembrane TatC homolog (TatCt) in haloarchaea, over and above the expected TatC topological variants, indicates a strong correlation between the additional homologs and the large number of substrates transported via the haloarchaeal Tat pathway. Various combinations of TatC homologs with different topologies—TatCo, TatCt, TatCn, and TatCx have been observed in haloarchaea. In this report, on the basis of these combinations we have segregated all haloarchaeal Tat substrates into two groups. The first group consists of substrates that are transported by TatCt alone, whereas the second group consists of substrates that are transported by the other TatC homologs (TatCo, TatCn, and TatCx). The various haloarchaea TatA components also shows the possible segregation towards the substrates. We have also identified the possible homologs for Tat substrate chaperones, which act as a quality-control mechanism for proper protein folding. Further sequence analysis implies that the two TatC domains of TatCt complement each other's functionally. Substrate analysis also revealed subtle differences between the substrates being transported by various homologs: further experimental analysis is therefore required for better understanding of the complexities of the haloarchaeal Tat pathway.
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Affiliation(s)
- Deepanjan Ghosh
- Division of Biochemical Sciences, CSIR-National Chemical Laboratory, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad- 201002, India
| | - Debjyoti Boral
- Division of Biochemical Sciences, CSIR-National Chemical Laboratory, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad- 201002, India
| | - Koteswara Rao Vankudoth
- Division of Biochemical Sciences, CSIR-National Chemical Laboratory, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad- 201002, India
| | - Sureshkumar Ramasamy
- Division of Biochemical Sciences, CSIR-National Chemical Laboratory, Pune 411008, India
- Corresponding author.
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9
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SignalP 5.0 improves signal peptide predictions using deep neural networks. Nat Biotechnol 2019; 37:420-423. [PMID: 30778233 DOI: 10.1038/s41587-019-0036-z] [Citation(s) in RCA: 2528] [Impact Index Per Article: 505.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 01/16/2019] [Indexed: 11/08/2022]
Abstract
Signal peptides (SPs) are short amino acid sequences in the amino terminus of many newly synthesized proteins that target proteins into, or across, membranes. Bioinformatic tools can predict SPs from amino acid sequences, but most cannot distinguish between various types of signal peptides. We present a deep neural network-based approach that improves SP prediction across all domains of life and distinguishes between three types of prokaryotic SPs.
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10
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Pohlschroder M, Pfeiffer F, Schulze S, Abdul Halim MF. Archaeal cell surface biogenesis. FEMS Microbiol Rev 2018; 42:694-717. [PMID: 29912330 PMCID: PMC6098224 DOI: 10.1093/femsre/fuy027] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 06/12/2018] [Indexed: 12/13/2022] Open
Abstract
Cell surfaces are critical for diverse functions across all domains of life, from cell-cell communication and nutrient uptake to cell stability and surface attachment. While certain aspects of the mechanisms supporting the biosynthesis of the archaeal cell surface are unique, likely due to important differences in cell surface compositions between domains, others are shared with bacteria or eukaryotes or both. Based on recent studies completed on a phylogenetically diverse array of archaea, from a wide variety of habitats, here we discuss advances in the characterization of mechanisms underpinning archaeal cell surface biogenesis. These include those facilitating co- and post-translational protein targeting to the cell surface, transport into and across the archaeal lipid membrane, and protein anchoring strategies. We also discuss, in some detail, the assembly of specific cell surface structures, such as the archaeal S-layer and the type IV pili. We will highlight the importance of post-translational protein modifications, such as lipid attachment and glycosylation, in the biosynthesis as well as the regulation of the functions of these cell surface structures and present the differences and similarities in the biogenesis of type IV pili across prokaryotic domains.
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Affiliation(s)
| | - Friedhelm Pfeiffer
- Computational Biology Group, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Stefan Schulze
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
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11
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Proteolytic systems of archaea: slicing, dicing, and mincing in the extreme. Emerg Top Life Sci 2018; 2:561-580. [PMID: 32953999 DOI: 10.1042/etls20180025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Archaea are phylogenetically distinct from bacteria, and some of their proteolytic systems reflect this distinction. Here, the current knowledge of archaeal proteolysis is reviewed as it relates to protein metabolism, protein homeostasis, and cellular regulation including targeted proteolysis by proteasomes associated with AAA-ATPase networks and ubiquitin-like modification. Proteases and peptidases that facilitate the recycling of peptides to amino acids as well as membrane-associated and integral membrane proteases are also reviewed.
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12
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Evaluating a New High-throughput Twin-Arginine Translocase Assay in Bacteria for Therapeutic Applications. Curr Microbiol 2017; 74:1332-1336. [DOI: 10.1007/s00284-017-1321-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 07/25/2017] [Indexed: 10/19/2022]
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13
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Ding Y, Nash J, Berezuk A, Khursigara CM, Langelaan DN, Smith SP, Jarrell KF. Identification of the first transcriptional activator of an archaellum operon in a euryarchaeon. Mol Microbiol 2016; 102:54-70. [PMID: 27314758 DOI: 10.1111/mmi.13444] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/16/2016] [Indexed: 12/21/2022]
Abstract
The archaellum is the swimming organelle of the third domain, the Archaea. In the euryarchaeon Methanococcus maripaludis, genes involved in archaella formation, including the three archaellins flaB1, flaB2 and flaB3, are mainly located in the fla operon. Previous studies have shown that transcription of fla genes and expression of Fla proteins are regulated under different growth conditions. In this study, we identify MMP1718 as the first transcriptional activator that directly regulates the fla operon in M. maripaludis. Mutants carrying an in-frame deletion in mmp1718 did not express FlaB2 detected by western blotting. Quantitative reverse transcription PCR analysis of purified RNA from the Δmmp1718 mutant showed that transcription of flaB2 was negligible compared to wildtype cells. In addition, no archaella were observed on the cell surface of the Δmmp1718 mutant. FlaB2 expression and archaellation were restored when the Δmmp1718 mutant was complemented with mmp1718 in trans. Electrophoretic motility shift assay and isothermal titration calorimetry results demonstrated the specific binding of purified MMP1718 to DNA fragments upstream of the fla promoter. Four 6 bp consensus sequences were found immediately upstream of the fla promoter and are considered the putative MMP1718-binding sites. Herein, we designate MMP1718 as EarA, the first euryarchaeal archaellum regulator.
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Affiliation(s)
- Yan Ding
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - John Nash
- Laboratory for Foodborne Zoonoses, Public Health Agency of Canada, Guelph, Ontario, N1G 3W4, Canada
| | - Alison Berezuk
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | - Cezar M Khursigara
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | - David N Langelaan
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Steven P Smith
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Ken F Jarrell
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada.
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14
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Effects of growth conditions on archaellation and N-glycosylation in Methanococcus maripaludis. Microbiology (Reading) 2016; 162:339-350. [DOI: 10.1099/mic.0.000221] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
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15
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Perras AK, Daum B, Ziegler C, Takahashi LK, Ahmed M, Wanner G, Klingl A, Leitinger G, Kolb-Lenz D, Gribaldo S, Auerbach A, Mora M, Probst AJ, Bellack A, Moissl-Eichinger C. S-layers at second glance? Altiarchaeal grappling hooks (hami) resemble archaeal S-layer proteins in structure and sequence. Front Microbiol 2015; 6:543. [PMID: 26106369 PMCID: PMC4460559 DOI: 10.3389/fmicb.2015.00543] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 05/17/2015] [Indexed: 01/02/2023] Open
Abstract
The uncultivated “Candidatus Altiarchaeum hamiconexum” (formerly known as SM1 Euryarchaeon) carries highly specialized nano-grappling hooks (“hami”) on its cell surface. Until now little is known about the major protein forming these structured fibrous cell surface appendages, the genes involved or membrane anchoring of these filaments. These aspects were analyzed in depth in this study using environmental transcriptomics combined with imaging methods. Since a laboratory culture of this archaeon is not yet available, natural biofilm samples with high Ca. A. hamiconexum abundance were used for the entire analyses. The filamentous surface appendages spanned both membranes of the cell, which are composed of glycosyl-archaeol. The hami consisted of multiple copies of the same protein, the corresponding gene of which was identified via metagenome-mapped transcriptome analysis. The hamus subunit proteins, which are likely to self-assemble due to their predicted beta sheet topology, revealed no similiarity to known microbial flagella-, archaella-, fimbriae- or pili-proteins, but a high similarity to known S-layer proteins of the archaeal domain at their N-terminal region (44–47% identity). Our results provide new insights into the structure of the unique hami and their major protein and indicate their divergent evolution with S-layer proteins.
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Affiliation(s)
- Alexandra K Perras
- Department of Internal Medicine, Medical University of Graz Graz, Austria ; Department of Microbiology and Archaea Center, University of Regensburg Regensburg, Germany
| | - Bertram Daum
- Department of Structural Biology, Max Planck Institute of Biophysics Frankfurt, Germany
| | - Christine Ziegler
- Department of Biophysics, University of Regensburg Regensburg, Germany
| | - Lynelle K Takahashi
- Chemical Sciences Division, Lawrence Berkeley National Laboratory Berkeley, CA, USA
| | - Musahid Ahmed
- Chemical Sciences Division, Lawrence Berkeley National Laboratory Berkeley, CA, USA
| | - Gerhard Wanner
- Faculty of Biology, Ludwig-Maximilians-University of Munich Munich, Germany
| | - Andreas Klingl
- Faculty of Biology, Ludwig-Maximilians-University of Munich Munich, Germany
| | - Gerd Leitinger
- Research Unit Electron Microscopic Techniques, Institute of Cell Biology, Histology and Embryology, Medical University of Graz Graz, Austria
| | - Dagmar Kolb-Lenz
- Institute of Cell Biology, Histology and Embryology, Medical University of Graz Graz, Austria ; Core Facility Ultrastructure, Analysis, Center for Medical Research Institute, Medical University of Graz Graz, Austria
| | - Simonetta Gribaldo
- Unité Biologie Moléculaire du Gene chez les Extrêmophiles, Departément de Microbiologie, Institut Pasteur Paris, France
| | - Anna Auerbach
- Department of Microbiology and Archaea Center, University of Regensburg Regensburg, Germany
| | - Maximilian Mora
- Department of Internal Medicine, Medical University of Graz Graz, Austria
| | - Alexander J Probst
- Department of Earth and Planetary Science, University of California, Berkeley Berkeley, CA, USA
| | - Annett Bellack
- Department of Microbiology and Archaea Center, University of Regensburg Regensburg, Germany
| | - Christine Moissl-Eichinger
- Department of Internal Medicine, Medical University of Graz Graz, Austria ; Department of Microbiology and Archaea Center, University of Regensburg Regensburg, Germany ; BioTechMed-Graz Graz, Austria
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16
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Jarrell KF, Ding Y, Meyer BH, Albers SV, Kaminski L, Eichler J. N-linked glycosylation in Archaea: a structural, functional, and genetic analysis. Microbiol Mol Biol Rev 2014; 78:304-41. [PMID: 24847024 PMCID: PMC4054257 DOI: 10.1128/mmbr.00052-13] [Citation(s) in RCA: 146] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
N-glycosylation of proteins is one of the most prevalent posttranslational modifications in nature. Accordingly, a pathway with shared commonalities is found in all three domains of life. While excellent model systems have been developed for studying N-glycosylation in both Eukarya and Bacteria, an understanding of this process in Archaea was hampered until recently by a lack of effective molecular tools. However, within the last decade, impressive advances in the study of the archaeal version of this important pathway have been made for halophiles, methanogens, and thermoacidophiles, combining glycan structural information obtained by mass spectrometry with bioinformatic, genetic, biochemical, and enzymatic data. These studies reveal both features shared with the eukaryal and bacterial domains and novel archaeon-specific aspects. Unique features of N-glycosylation in Archaea include the presence of unusual dolichol lipid carriers, the use of a variety of linking sugars that connect the glycan to proteins, the presence of novel sugars as glycan constituents, the presence of two very different N-linked glycans attached to the same protein, and the ability to vary the N-glycan composition under different growth conditions. These advances are the focus of this review, with an emphasis on N-glycosylation pathways in Haloferax, Methanococcus, and Sulfolobus.
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Affiliation(s)
- Ken F Jarrell
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Yan Ding
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Benjamin H Meyer
- Molecular Biology of Archaea, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Sonja-Verena Albers
- Molecular Biology of Archaea, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Lina Kaminski
- Department of Life Sciences, Ben Gurion University, Beersheva, Israel
| | - Jerry Eichler
- Department of Life Sciences, Ben Gurion University, Beersheva, Israel
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Nair DB, Uchida K, Aizawa SI, Jarrell KF. Genetic analysis of a type IV pili-like locus in the archaeon Methanococcus maripaludis. Arch Microbiol 2014; 196:179-91. [PMID: 24493292 DOI: 10.1007/s00203-014-0956-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 12/28/2013] [Accepted: 01/24/2014] [Indexed: 12/29/2022]
Abstract
Methanococcus maripaludis is a stringently anaerobic archaeon with two studied surface structures, archaella and type IV pili. Previously, it was shown that three pilin genes (mmp0233 [epdA], mmp0236 [epdB] and mmp0237 [epdC]) located within an 11 gene cluster in the genome were necessary for normal piliation. This study focused on analysis of the remaining genes to determine their potential involvement in piliation. Reverse transcriptase PCR experiments demonstrated the 11 genes formed a single transcriptional unit. Deletions were made in all the non-pilin genes except mmp0231. Electron microscopy revealed that all the genes in the locus except mmp0235 and mmp0238 were essential for piliation. Complementation with a plasmid-borne wild-type copy of the deleted gene restored at least some piliation. We identified genes for an assembly ATPase and two versions of the conserved pilin platform forming protein necessary for pili assembly at a separate genetic locus.
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Affiliation(s)
- Divya B Nair
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, K7L 3N6, Canada
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Nair DB, Chung DKC, Schneider J, Uchida K, Aizawa SI, Jarrell KF. Identification of an additional minor pilin essential for piliation in the archaeon Methanococcus maripaludis. PLoS One 2013; 8:e83961. [PMID: 24386316 PMCID: PMC3875500 DOI: 10.1371/journal.pone.0083961] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 11/11/2013] [Indexed: 11/19/2022] Open
Abstract
Methanococcus maripaludis is an archaeon with two studied surface appendages, archaella and type IV-like pili. Previously, the major structural pilin was identified as MMP1685 and three additional proteins were designated as minor pilins (EpdA, EpdB and EpdC). All of the proteins are likely processed by the pilin-specific prepilin peptidase EppA. Six other genes were identified earlier as likely encoding pilin proteins processed also by EppA. In this study, each of the six genes (mmp0528, mmp0600, mmp0601, mmp0709, mmp0903 and mmp1283) was deleted and the mutants examined by electron microscopy to determine their essentiality for pili formation. While mRNA transcripts of all genes were detected by RT-PCR, only the deletion of mmp1283 led to nonpiliated cells. This strain could be complemented back to a piliated state by supplying a wildtype copy of the mmp1283 gene in trans. This study adds to the complexity of the type IV pili system in M. maripaludis and raises questions about the functions of the remaining five pilin-like genes and whether M. maripaludis under other growth conditions may be able to assemble additional pili-like structures.
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Affiliation(s)
- Divya B Nair
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Daniel K C Chung
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - James Schneider
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Kaoru Uchida
- Department of Life Sciences, Prefectural University of Hiroshima, 562 Nanatsuka, Shobara, Hiroshima, Japan
| | - Shin-Ichi Aizawa
- Department of Life Sciences, Prefectural University of Hiroshima, 562 Nanatsuka, Shobara, Hiroshima, Japan
| | - Ken F Jarrell
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
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Schmid G, Mathiesen G, Arntzen MO, Eijsink VGH, Thomm M. Experimental and computational analysis of the secretome of the hyperthermophilic archaeon Pyrococcus furiosus. Extremophiles 2013; 17:921-30. [PMID: 23979514 PMCID: PMC3824201 DOI: 10.1007/s00792-013-0574-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Accepted: 07/30/2013] [Indexed: 11/24/2022]
Abstract
Although Pyrococcus furiosus is one of the best studied hyperthermophilic archaea, to date no experimental investigation of the extent of protein secretion has been performed. We describe experimental verification of the extracellular proteome of P. furiosus grown on starch. LC-MS/MS-based analysis of culture supernatants led to the identification of 58 proteins. Fifteen of these proteins had a putative N-terminal signal peptide (SP), tagging the proteins for translocation across the membrane. The detected proteins with predicted SPs and known function were almost exclusively involved in important extracellular functions, like substrate degradation or transport. Most of the 43 proteins without predicted N-terminal signal sequences are known to have intracellular functions, mainly (70 %) related to intracellular metabolism. In silico analyses indicated that the genome of P. furiosus encodes 145 proteins with N-terminal SPs, including 21 putative lipoproteins and 17 with a class III peptide. From these we identified 15 (10 %; 7 SPI, 3 SPIII and 5 lipoproteins) under the specific growth conditions of this study. The putative lipoprotein signal peptides have a unique sequence motif, distinct from the motifs in bacteria and other archaeal orders.
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Affiliation(s)
- G. Schmid
- Hyperthermics Regensburg GmbH, Josef-Engert-Straße 9, 93053 Regensburg, Germany
| | - G. Mathiesen
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, P.O. Box 5003, 1432 Aas, Norway
| | - M. O. Arntzen
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, P.O. Box 5003, 1432 Aas, Norway
- Biotechnology Centre of Oslo, University of Oslo, 0317 Oslo, Norway
| | - V. G. H. Eijsink
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, P.O. Box 5003, 1432 Aas, Norway
| | - M. Thomm
- Lehrstuhl für Mikrobiologie, Universität Regensburg, Universitätsstr. 31, 93053 Regensburg, Germany
- Hyperthermics Regensburg GmbH, Josef-Engert-Straße 9, 93053 Regensburg, Germany
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Abstract
The Sec pathway for export of proteins across the cytoplasmic membrane to the bacterial periplasm and outer membrane was the first secretion pathway to be discovered in bacteria. A combination of bacterial genetics, development of an in vitro membrane vesicle system and the concurrent elaboration of the signal hypothesis from studies on eukaryotes led to the identification and characterization of two pathways leading to protein export through the SecYEG cytoplasmic membrane translocon. The Sec pathway is also required for assembly of proteins into the cytoplasmic membrane. Since the membrane translocon for Sec pathways is conserved across the three domains of life, the history of research progress in eukaryotes and bacteria was facilitated by the close interaction between those studying both classes of organisms.
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Affiliation(s)
- Jon Beckwith
- Department of Microbiology and Immunobiology, Harvard Medical School, HIM Building, Room 1047,77 Avenue Louis Pasteur, Boston, MA 02115, USA.
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21
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Eichler J, Maupin-Furlow J. Post-translation modification in Archaea: lessons from Haloferax volcanii and other haloarchaea. FEMS Microbiol Rev 2012; 37:583-606. [PMID: 23167813 DOI: 10.1111/1574-6976.12012] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Revised: 11/13/2012] [Accepted: 11/13/2012] [Indexed: 01/11/2023] Open
Abstract
As an ever-growing number of genome sequences appear, it is becoming increasingly clear that factors other than genome sequence impart complexity to the proteome. Of the various sources of proteomic variability, post-translational modifications (PTMs) most greatly serve to expand the variety of proteins found in the cell. Likewise, modulating the rates at which different proteins are degraded also results in a constantly changing cellular protein profile. While both strategies for generating proteomic diversity are adopted by organisms across evolution, the responsible pathways and enzymes in Archaea are often less well described than are their eukaryotic and bacterial counterparts. Studies on halophilic archaea, in particular Haloferax volcanii, originally isolated from the Dead Sea, are helping to fill the void. In this review, recent developments concerning PTMs and protein degradation in the haloarchaea are discussed.
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Affiliation(s)
- Jerry Eichler
- Department of Life Sciences, Ben Gurion University, Beersheva, Israel.
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Szabo Z, Pohlschroder M. Diversity and subcellular distribution of archaeal secreted proteins. Front Microbiol 2012; 3:207. [PMID: 22783239 PMCID: PMC3387779 DOI: 10.3389/fmicb.2012.00207] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Accepted: 05/21/2012] [Indexed: 12/12/2022] Open
Abstract
Secreted proteins make up a significant percentage of a prokaryotic proteome and play critical roles in important cellular processes such as polymer degradation, nutrient uptake, signal transduction, cell wall biosynthesis, and motility. The majority of archaeal proteins are believed to be secreted either in an unfolded conformation via the universally conserved Sec pathway or in a folded conformation via the Twin arginine transport (Tat) pathway. Extensive in vivo and in silico analyses of N-terminal signal peptides that target proteins to these pathways have led to the development of computational tools that not only predict Sec and Tat substrates with high accuracy but also provide information about signal peptide processing and targeting. Predictions therefore include indications as to whether a substrate is a soluble secreted protein, a membrane or cell wall anchored protein, or a surface structure subunit, and whether it is targeted for post-translational modification such as glycosylation or the addition of a lipid. The use of these in silico tools, in combination with biochemical and genetic analyses of transport pathways and their substrates, has resulted in improved predictions of the subcellular localization of archaeal secreted proteins, allowing for a more accurate annotation of archaeal proteomes, and has led to the identification of potential adaptations to extreme environments, as well as phyla-specific pathways among the archaea. A more comprehensive understanding of the transport pathways used and post-translational modifications of secreted archaeal proteins will also facilitate the identification and heterologous expression of commercially valuable archaeal enzymes.
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Jarrell KF, Walters AD, Bochiwal C, Borgia JM, Dickinson T, Chong JPJ. Major players on the microbial stage: why archaea are important. MICROBIOLOGY-SGM 2011; 157:919-936. [PMID: 21330437 DOI: 10.1099/mic.0.047837-0] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
As microbiology undergoes a renaissance, fuelled in part by developments in new sequencing technologies, the massive diversity and abundance of microbes becomes yet more obvious. The Archaea have traditionally been perceived as a minor group of organisms forced to evolve into environmental niches not occupied by their more 'successful' and 'vigorous' counterparts, the bacteria. Here we outline some of the evidence gathered by an increasingly large and productive group of scientists that demonstrates not only that the Archaea contribute significantly to global nutrient cycling, but also that they compete successfully in 'mainstream' environments. Recent data suggest that the Archaea provide the major routes for ammonia oxidation in the environment. Archaea also have huge economic potential that to date has only been fully realized in the production of thermostable polymerases. Archaea have furnished us with key paradigms for understanding fundamentally conserved processes across all domains of life. In addition, they have provided numerous exemplars of novel biological mechanisms that provide us with a much broader view of the forms that life can take and the way in which micro-organisms can interact with other species. That this information has been garnered in a relatively short period of time, and appears to represent only a small proportion of what the Archaea have to offer, should provide further incentives to microbiologists to investigate the underlying biology of this fascinating domain.
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Affiliation(s)
- Ken F Jarrell
- Department of Microbiology and Immunology, Queen's University, Kingston, ON K7L 3N6, Canada
| | - Alison D Walters
- Department of Biology, University of York, Wentworth Way, Heslington, York YO10 5DD, UK
| | - Chitvan Bochiwal
- Department of Biology, University of York, Wentworth Way, Heslington, York YO10 5DD, UK
| | - Juliet M Borgia
- Department of Biology, University of York, Wentworth Way, Heslington, York YO10 5DD, UK
| | - Thomas Dickinson
- Sheffield Hallam University, City Campus, Howard Street, Sheffield S1 1WB, UK
| | - James P J Chong
- Department of Biology, University of York, Wentworth Way, Heslington, York YO10 5DD, UK
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Maldonado B, Kneuper H, Buchanan G, Hatzixanthis K, Sargent F, Berks BC, Palmer T. Characterisation of the membrane-extrinsic domain of the TatB component of the twin arginine protein translocase. FEBS Lett 2011; 585:478-84. [DOI: 10.1016/j.febslet.2011.01.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Revised: 12/21/2010] [Accepted: 01/03/2011] [Indexed: 11/30/2022]
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Genetic and mass spectrometry analyses of the unusual type IV-like pili of the archaeon Methanococcus maripaludis. J Bacteriol 2010; 193:804-14. [PMID: 21075925 DOI: 10.1128/jb.00822-10] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The structure of pili from the archaeon Methanococcus maripaludis is unlike that of any bacterial pili. However, genetic analysis of the genes involved in the formation of these pili has been lacking until this study. Pili were isolated from a nonflagellated (ΔflaK) mutant and shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to consist primarily of subunits with an apparent molecular mass of 17 kDa. In-frame deletions were created in three genes, MMP0233, MMP0236, and MMP0237, which encode proteins with bacterial type IV pilin-like signal peptides previously identified by in silico methodology as likely candidates for pilus structural proteins. Deletion of MMP0236 or MMP0237 resulted in mutant cells completely devoid of pili on the cell surface, while deletion of the third pilin-like gene, MMP0233, resulted in cells greatly reduced in the number of pili on the surface. Complementation with the deleted gene in each case returned the cells to a piliated state. Surprisingly, mass spectrometry analysis of purified pili identified the major structural pilin as another type IV pilin-like protein, MMP1685, whose gene is located outside the first pilus locus. This protein was found to be glycosylated with an N-linked branched pentasaccharide glycan. Deletion and complementation analysis confirmed that MMP1685 is required for piliation.
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Biosynthesis and role of N-linked glycosylation in cell surface structures of archaea with a focus on flagella and s layers. Int J Microbiol 2010; 2010:470138. [PMID: 20976295 PMCID: PMC2952790 DOI: 10.1155/2010/470138] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Accepted: 08/01/2010] [Indexed: 11/17/2022] Open
Abstract
The genetics and biochemistry of the N-linked glycosylation system of Archaea have been investigated over the past 5 years using flagellins and S layers as reporter proteins in the model organisms, Methanococcus voltae, Methanococcus maripaludis, and Haloferax volcanii. Structures of archaeal N-linked glycans have indicated a variety of linking sugars as well as unique sugar components. In M. voltae, M. maripaludis, and H. volcanii, a number of archaeal glycosylation genes (agl) have been identified by deletion and complementation studies. These include many of the glycosyltransferases and the oligosaccharyltransferase needed to assemble the glycans as well as some of the genes encoding enzymes required for the biosynthesis of the sugars themselves. The N-linked glycosylation system is not essential for any of M. voltae, M. maripaludis, or H. volcanii, as demonstrated by the successful isolation of mutants carrying deletions in the oligosaccharyltransferase gene aglB (a homologue of the eukaryotic Stt3 subunit of the oligosaccharyltransferase complex). However, mutations that affect the glycan structure have serious effects on both flagellation and S layer function.
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Bagos PG, Nikolaou EP, Liakopoulos TD, Tsirigos KD. Combined prediction of Tat and Sec signal peptides with hidden Markov models. ACTA ACUST UNITED AC 2010; 26:2811-7. [PMID: 20847219 DOI: 10.1093/bioinformatics/btq530] [Citation(s) in RCA: 169] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
MOTIVATION Computational prediction of signal peptides is of great importance in computational biology. In addition to the general secretory pathway (Sec), Bacteria, Archaea and chloroplasts possess another major pathway that utilizes the Twin-Arginine translocase (Tat), which recognizes longer and less hydrophobic signal peptides carrying a distinctive pattern of two consecutive Arginines (RR) in the n-region. A major functional differentiation between the Sec and Tat export pathways lies in the fact that the former translocates secreted proteins unfolded through a protein-conducting channel, whereas the latter translocates completely folded proteins using an unknown mechanism. The purpose of this work is to develop a novel method for predicting and discriminating Sec from Tat signal peptides at better accuracy. RESULTS We report the development of a novel method, PRED-TAT, which is capable of discriminating Sec from Tat signal peptides and predicting their cleavage sites. The method is based on Hidden Markov Models and possesses a modular architecture suitable for both Sec and Tat signal peptides. On an independent test set of experimentally verified Tat signal peptides, PRED-TAT clearly outperforms the previously proposed methods TatP and TATFIND, whereas, when evaluated as a Sec signal peptide predictor compares favorably to top-scoring predictors such as SignalP and Phobius. The method is freely available for academic users at http://www.compgen.org/tools/PRED-TAT/.
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Affiliation(s)
- Pantelis G Bagos
- Department of Computer Science and Biomedical Informatics, University of Central Greece, Papasiopoulou 2-4, Lamia 35100, Greece.
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S-layer glycoproteins and flagellins: reporters of archaeal posttranslational modifications. ARCHAEA-AN INTERNATIONAL MICROBIOLOGICAL JOURNAL 2010; 2010. [PMID: 20721273 PMCID: PMC2913515 DOI: 10.1155/2010/612948] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2010] [Accepted: 06/15/2010] [Indexed: 01/06/2023]
Abstract
Many archaeal proteins undergo posttranslational modifications. S-layer proteins and flagellins have been used successfully to study a variety of these modifications, including N-linked glycosylation, signal peptide removal and lipid modification. Use of these well-characterized reporter proteins in the genetically tractable model organisms, Haloferax volcanii, Methanococcus voltae and Methanococcus maripaludis, has allowed dissection of the pathways and characterization of many of the enzymes responsible for these modifications. Such studies have identified archaeal-specific variations in signal peptidase activity not found in the other domains of life, as well as the enzymes responsible for assembly and biosynthesis of novel N-linked glycans. In vitro assays for some of these enzymes have already been developed. N-linked glycosylation is not essential for either Hfx. volcanii or the Methanococcus species, an observation that allowed researchers to analyze the role played by glycosylation in the function of both S-layers and flagellins, by generating mutants possessing these reporters with only partial attached glycans or lacking glycan altogether. In future studies, it will be possible to consider questions related to the heterogeneity associated with given modifications, such as differential or modulated glycosylation.
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Archaea signal recognition particle shows the way. ARCHAEA-AN INTERNATIONAL MICROBIOLOGICAL JOURNAL 2010; 2010:485051. [PMID: 20672053 PMCID: PMC2905702 DOI: 10.1155/2010/485051] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2010] [Accepted: 05/14/2010] [Indexed: 01/24/2023]
Abstract
Archaea SRP is composed of an SRP RNA molecule and two bound proteins named SRP19 and SRP54. Regulated by the binding and hydrolysis of guanosine triphosphates, the RNA-bound SRP54 protein transiently associates not only with the hydrophobic signal sequence as it emerges from the ribosomal exit tunnel, but also interacts with the membrane-associated SRP receptor (FtsY). Comparative analyses of the archaea genomes and their SRP component sequences, combined with structural and biochemical data, support a prominent role of the SRP RNA in the assembly and function of the archaea SRP. The 5e motif, which in eukaryotes binds a 72 kilodalton protein, is preserved in most archaea SRP RNAs despite the lack of an archaea SRP72 homolog. The primary function of the 5e region may be to serve as a hinge, strategically positioned between the small and large SRP domain, allowing the elongated SRP to bind simultaneously to distant ribosomal sites. SRP19, required in eukaryotes for initiating SRP assembly, appears to play a subordinate role in the archaea SRP or may be defunct. The N-terminal A region and a novel C-terminal R region of the archaea SRP receptor (FtsY) are strikingly diverse or absent even among the members of a taxonomic subgroup.
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Different minimal signal peptide lengths recognized by the archaeal prepilin-like peptidases FlaK and PibD. J Bacteriol 2009; 191:6732-40. [PMID: 19717585 DOI: 10.1128/jb.00673-09] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Archaea, the preflagellin peptidase (a type IV prepilin-like peptidase designated FlaK in Methanococcus voltae and Methanococcus maripaludis) is the enzyme that cleaves the N-terminal signal peptide from preflagellins. In methanogens and several other archaeal species, the typical flagellin signal peptide length is 11 to 12 amino acids, while in other archaea preflagellins possess extremely short signal peptides. A systematic approach to address the signal peptide length requirement for preflagellin processing is presented in this study. M. voltae preflagellin FlaB2 proteins with signal peptides 3 to 12 amino acids in length were generated and used as a substrate in an in vitro assay utilizing M. voltae membranes as an enzyme source. Processing by FlaK was observed in FlaB2 proteins containing signal peptides shortened to 5 amino acids; signal peptides 4 or 3 amino acids in length were unprocessed. In the case of Sulfolobus solfataricus, where the preflagellin peptidase PibD has broader substrate specificity, some predicted substrates have predicted signal peptides as short as 3 amino acids. Interestingly, the shorter signal peptides of the various mutant FlaB2 proteins not processed by FlaK were processed by PibD, suggesting that some archaeal preflagellin peptidases are likely adapted toward cleaving shorter signal peptides. The functional complementation of signal peptidase activity by FlaK and PibD in an M. maripaludis DeltaflaK mutant indicated that processing of preflagellins was detected by complementation with either FlaK or PibD, yet only FlaK-complemented cells were flagellated. This suggested that a block in an assembly step subsequent to signal peptide removal occurred in the PibD complementation.
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Palmieri G, Cannio R, Fiume I, Rossi M, Pocsfalvi G. Outside the unusual cell wall of the hyperthermophilic archaeon Aeropyrum pernix K1. Mol Cell Proteomics 2009; 8:2570-81. [PMID: 19640852 DOI: 10.1074/mcp.m900012-mcp200] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In contrast to the extensively studied eukaryal and bacterial protein secretion systems, comparatively less is known about how and which proteins cross the archaeal cell membrane. To identify secreted proteins of the hyperthermophilic archaeon Aeropyrum pernix K1 we used a proteomics approach to analyze the extracellular and cell surface protein fractions. The experimentally obtained data comprising 107 proteins were compared with the in silico predicted secretome. Because of the lack of signal peptide and cellular localization prediction tools specific for archaeal species, programs trained on eukaryotic and/or Gram-positive and Gram-negative bacterial signal peptide data sets were used. PSortB Gram-negative and Gram-positive analysis predicted 21 (1.2% of total ORFs) and 24 (1.4% of total ORFs) secreted proteins, respectively, from the entire A. pernix K1 proteome, 12 of which were experimentally identified in this work. Six additional proteins were predicted to follow non-classical secretion mechanisms using SecP algorithms. According to at least one of the two PSortB predictions, 48 proteins identified in the two fractions possess an unknown localization site. In addition, more than half of the proteins do not contain signal peptides recognized by current prediction programs. This suggests that known mechanisms only partly describe archaeal protein secretion. The most striking characteristic of the secretome was the high number of transport-related proteins identified from the ATP-binding cassette (ABC), tripartite ATP-independent periplasmic, ATPase, small conductance mechanosensitive ion channel (MscS), and dicarboxylate amino acid-cation symporter transporter families. In particular, identification of 21 solute-binding receptors of the ABC superfamily of the 24 predicted in silico confirms that ABC-mediated transport represents the most frequent strategy adopted by A. pernix for solute translocation across the cell membrane.
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Affiliation(s)
- Gianna Palmieri
- Institute of Protein Biochemistry-National Research Council, 80131 Naples, Italy
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Albers SV, Pohlschröder M. Diversity of archaeal type IV pilin-like structures. Extremophiles 2009; 13:403-10. [PMID: 19347566 DOI: 10.1007/s00792-009-0241-7] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2009] [Accepted: 03/22/2009] [Indexed: 11/26/2022]
Abstract
Bacterial type IV pili perform important functions in such disparate biological processes as surface adhesion, cell-cell interactions, autoaggregation, conjugation, and twitching motility. Unlike bacteria, archaea use a type IV pilus related structure to drive swimming motility. While this unique flagellum is the best-studied example of an archaeal IV pilus-like structure, recent in silico, in vivo and structural analyses have revealed a highly diverse set of archaeal non-flagellar type IV pilus-like structures. Accumulating evidence suggests that these structures play important diverse roles in archaea.
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Affiliation(s)
- Sonja-Verena Albers
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch Strasse, 35043, Marburg, Germany.
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A single Sec61-complex functions as a protein-conducting channel. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:2375-83. [DOI: 10.1016/j.bbamcr.2008.08.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Revised: 08/06/2008] [Accepted: 08/06/2008] [Indexed: 12/30/2022]
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Bagos PG, Tsirigos KD, Plessas SK, Liakopoulos TD, Hamodrakas SJ. Prediction of signal peptides in archaea. Protein Eng Des Sel 2008; 22:27-35. [PMID: 18988691 DOI: 10.1093/protein/gzn064] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Computational prediction of signal peptides (SPs) and their cleavage sites is of great importance in computational biology; however, currently there is no available method capable of predicting reliably the SPs of archaea, due to the limited amount of experimentally verified proteins with SPs. We performed an extensive literature search in order to identify archaeal proteins having experimentally verified SP and managed to find 69 such proteins, the largest number ever reported. A detailed analysis of these sequences revealed some unique features of the SPs of archaea, such as the unique amino acid composition of the hydrophobic region with a higher than expected occurrence of isoleucine, and a cleavage site resembling more the sequences of gram-positives with almost equal amounts of alanine and valine at the position-3 before the cleavage site and a dominant alanine at position-1, followed in abundance by serine and glycine. Using these proteins as a training set, we trained a hidden Markov model method that predicts the presence of the SPs and their cleavage sites and also discriminates such proteins from cytoplasmic and transmembrane ones. The method performs satisfactorily, yielding a 35-fold cross-validation procedure, a sensitivity of 100% and specificity 98.41% with the Matthews' correlation coefficient being equal to 0.964. This particular method is currently the only available method for the prediction of secretory SPs in archaea, and performs consistently and significantly better compared with other available predictors that were trained on sequences of eukaryotic or bacterial origin. Searching 48 completely sequenced archaeal genomes we identified 9437 putative SPs. The method, PRED-SIGNAL, and the results are freely available for academic users at http://bioinformatics.biol.uoa.gr/PRED-SIGNAL/ and we anticipate that it will be a valuable tool for the computational analysis of archaeal genomes.
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Affiliation(s)
- P G Bagos
- Department of Cell Biology and Biophysics, Faculty of Biology, University of Athens, Athens 15701, Greece.
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Indicators from archaeal secretomes. Microbiol Res 2008; 165:1-10. [PMID: 18407482 DOI: 10.1016/j.micres.2008.03.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Revised: 02/14/2008] [Accepted: 03/01/2008] [Indexed: 11/21/2022]
Abstract
Just as in the Eukarya and the Bacteria, members of the Archaea need to export proteins beyond the cell membrane. This would be required to fulfill a variety of essential functions such as nutrient acquisition and biotransformations, maintenance of extracellular structures and more. Apart from the Eukarya and the Bacteria however, members of the Archaea share a number of unique characteristics. Does this uniqueness extend to the protein secretion system? It was the objective of this study to answer this question. To overcome the limited experimental information on secreted proteins in Archaea, this study was carried out by subjecting the available archaeal genomes, which represent halophiles, thermophiles, and extreme thermophiles, to bioinformatics analysis. Specifically, to examine the properties of the secretomes of the Archaea using the ExProt program. A total of 24 genomes were analyzed. Secretomes were found to fall in the range of 6% of total ORFs (Methanopyrus kandleri) to 19% (Halobacterium sp. NRC-1). Methanosarcina acetivorans has the highest fraction of lipoproteins (at 89) and the lowest (at 1) were members of the Thermoplasma, Pyrobaculum aerophilum, and Nanoarchaeum equitans. Based on the Tat consensus sequence, contribution of these secreted proteins to the secretomes were negligible, making up 8 proteins out of a total of 7105 predicted exported proteins. Amino acid composition, an attribute of signal peptides not used as a selection criteria by ExProt, of predicted archaeal signal peptides show that in the haloarchaea secretomes, the frequency of the amino acid Lys is much lower than that seen in bacterial signal peptides, but is compensated for by a higher frequency of Arg. It also showed that higher frequencies for Thr, Val, and Gly contribute to the hydrophobic character in haloarchaeal signal peptides, unlike bacterial signal peptides in which the hydrophobic character is dominated by Leu and Ile.
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Weiche B, Bürk J, Angelini S, Schiltz E, Thumfart JO, Koch HG. A cleavable N-terminal membrane anchor is involved in membrane binding of the Escherichia coli SRP receptor. J Mol Biol 2008; 377:761-73. [PMID: 18281057 DOI: 10.1016/j.jmb.2008.01.040] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Revised: 12/27/2007] [Accepted: 01/15/2008] [Indexed: 10/22/2022]
Abstract
Different from eukaryotes, the bacterial signal recognition particle (SRP) receptor lacks a membrane-tethering SRP receptor (SR) beta subunit and is composed of only the SR alpha homologue FtsY. FtsY is a modular protein composed of three domains. The N- and G-domains of FtsY are highly similar to the corresponding domains of Ffh/SRP54 and SR alpha and constitute the essential core of FtsY. In contrast, the weakly conserved N-terminal A-domain does not seem to be essential, and its exact function is unknown. Our data show that a 14-amino-acid-long positively charged region at the N-terminus of the A-domain is involved in stabilizing the FtsY-SecYEG interaction. Mutant analyses reveal that the positively charged residues are crucial for this function, and we propose that the 14-amino-acid region serves as a transient lipid anchor. In its absence, the activity of FtsY to support cotranslational integration is reduced to about 50%. Strikingly, in vivo, a truncated isoform of FtsY that lacks exactly these first 14 amino acids exists. Different from full-length FtsY, which primarily cofractionates with the membrane, the N-terminally truncated isoform is primarily present in the soluble fraction. Mutating the conserved glycine residue at position 14 prevents the formation of the truncated isoform and impairs the activity of FtsY in cotranslational targeting. These data suggest that membrane binding and function of FtsY are in part regulated by proteolytic cleavage of the conserved 14-amino-acid motif.
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Affiliation(s)
- Benjamin Weiche
- Institut für Biochemie und Molekularbiologie, Zentrum für Biochemie und Molekulare Zellforschung, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg, Germany
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Giménez MI, Dilks K, Pohlschröder M. Haloferax volcanii twin-arginine translocation substates include secreted soluble, C-terminally anchored and lipoproteins. Mol Microbiol 2007; 66:1597-606. [DOI: 10.1111/j.1365-2958.2007.06034.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Kuipers A, Wierenga J, Rink R, Kluskens LD, Driessen AJM, Kuipers OP, Moll GN. Sec-mediated transport of posttranslationally dehydrated peptides in Lactococcus lactis. Appl Environ Microbiol 2006; 72:7626-33. [PMID: 17041158 PMCID: PMC1694219 DOI: 10.1128/aem.01802-06] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2006] [Accepted: 10/02/2006] [Indexed: 11/20/2022] Open
Abstract
Nisin is a lanthionine-containing antimicrobial peptide produced by Lactococcus lactis. Its (methyl)lanthionines are introduced by two posttranslational enzymatic steps involving the dehydratase NisB, which dehydrates serine and threonine residues, and the cyclase NisC, which couples these dehydrated residues to cysteines, yielding thioether-bridged amino acids called lanthionines. The prenisin is subsequently exported by the ABC transporter NisT and extracellularly processed by the peptidase NisP. L. lactis expressing the nisBTC genes can modify and secrete a wide range of nonlantibiotic peptides. Here we demonstrate that in the absence of NisT and NisC, the Sec pathway of L. lactis can be exploited for the secretion of dehydrated variants of therapeutic peptides. Furthermore, posttranslational modifications by NisB and NisC still occur even when the nisin leader is preceded by a Sec signal peptide or a Tat signal peptide 27 or 44 amino acids long, respectively. However, transport of fully modified prenisin via the Sec pathway is impaired. The extent of NisB-mediated dehydration could be improved by raising the intracellular concentration NisB or by modulating the export efficiency through altering the signal sequence. These data demonstrate that besides the traditional lantibiotic transporter NisT, the Sec pathway with an established broad substrate range can be utilized for the improved export of lantibiotic enzyme-modified (poly)peptides.
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Affiliation(s)
- Anneke Kuipers
- BiOMaDe Technology Foundation, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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Albers SV, Szabó Z, Driessen AJM. Protein secretion in the Archaea: multiple paths towards a unique cell surface. Nat Rev Microbiol 2006; 4:537-47. [PMID: 16755286 DOI: 10.1038/nrmicro1440] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Archaea are similar to other prokaryotes in most aspects of cell structure but are unique with respect to the lipid composition of the cytoplasmic membrane and the structure of the cell surface. Membranes of archaea are composed of glycerol-ether lipids instead of glycerol-ester lipids and are based on isoprenoid side chains, whereas the cell walls are formed by surface-layer proteins. The unique cell surface of archaea requires distinct solutions to the problem of how proteins cross this barrier to be either secreted into the medium or assembled as appendages at the cell surface.
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Affiliation(s)
- Sonja-Verena Albers
- Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute and the Materials Science Centre Plus, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands
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