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Abstract
Bacterial proteases and peptidases are integral to cell physiology and stability, and their necessity in Streptococcus pneumoniae is no exception. Protein cleavage and processing mechanisms within the bacterial cell serve to ensure that the cell lives and functions in its commensal habitat and can respond to new environments presenting stressful conditions. For S. pneumoniae, the human nasopharynx is its natural habitat. In the context of virulence, movement of S. pneumoniae to the lungs, blood, or other sites can instigate responses by the bacteria that result in their proteases serving dual roles of self-protein processors and virulence factors of host protein targets.
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Affiliation(s)
- Mary E Marquart
- Department of Microbiology and Immunology, University of Mississippi Medical Center, Jackson, Mississippi USA
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2
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Abstract
Signal peptidases are the membrane bound enzymes that cleave off the amino-terminal signal peptide from secretory preproteins . There are two types of bacterial signal peptidases . Type I signal peptidase utilizes a serine/lysine catalytic dyad mechanism and is the major signal peptidase in most bacteria. Type II signal peptidase is an aspartic protease specific for prolipoproteins. This chapter will review what is known about the structure, function and mechanism of these unique enzymes.
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Affiliation(s)
- Mark Paetzel
- Department of Molecular Biology and Biochemistry, Simon Fraser University, South Science Building 8888 University Drive, Burnaby, BC, V5A 1S6, Canada.
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3
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Personne Y, Curtis MA, Wareham DW, Waite RD. Activity of the type I signal peptidase inhibitor MD3 against multidrug-resistant Gram-negative bacteria alone and in combination with colistin. J Antimicrob Chemother 2014; 69:3236-43. [PMID: 25134721 DOI: 10.1093/jac/dku309] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
OBJECTIVES Effective treatment of Gram-negative bacterial infections is increasingly challenging due to the spread of multidrug-resistant strains and a lack of new antimicrobials in development. Bacterial type I signal peptidases (SPases) represent a highly conserved and essential target for inhibition by novel compounds. SPases are required for the effective processing of membrane translocated proteins involved in core functions related to metabolism, virulence and resistance. In this study we assessed the biochemical and functional activity of a novel synthetic inhibitor (MD3) of SPases against a wide range of Gram-negative pathogens. METHODS The activity and specificity of MD3 for recombinant Pseudomonas aeruginosa SPase (LepB) and a genetically engineered LepB-regulatable strain were investigated. Antimicrobial activity of the compound alone and in combination with outer membrane-permeabilizing agents (sodium hexametaphosphate, colistin) was also determined against a collection of P. aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae and Stenotrophomonas maltophilia isolates. RESULTS MD3 was found to inactivate the P. aeruginosa LepB protein (IC50 10 μM), resulting in antimicrobial effects potentiated in the presence of colistin. MD3 also demonstrated potent activity against wild-type and multidrug-resistant strains of A. baumannii and S. maltophilia with MICs ranging from 0.5 to 14 mg/L in the presence of subinhibitory concentrations of colistin. CONCLUSIONS MD3 is a novel inhibitor of bacterial SPase in a range of non-fermentative Gram-negative bacteria. The antimicrobial activity is potentiated in combination with colistin and suggests that SPase inhibition warrants further exploration as a basis for future mono or combination therapies.
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Affiliation(s)
- Yoann Personne
- Centre for Immunology and Infectious Disease, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, 4 Newark Street, London E1 2AT, UK
| | - Michael A Curtis
- Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, 4 Newark Street, London E1 2AD, UK
| | - David W Wareham
- Centre for Immunology and Infectious Disease, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, 4 Newark Street, London E1 2AT, UK
| | - Richard D Waite
- Centre for Immunology and Infectious Disease, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, 4 Newark Street, London E1 2AT, UK
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4
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Zhang W, Xia Y. ER type I signal peptidase subunit (LmSPC1) is essential for the survival of Locusta migratoria manilensis and affects moulting, feeding, reproduction and embryonic development. INSECT MOLECULAR BIOLOGY 2014; 23:269-285. [PMID: 24467622 DOI: 10.1111/imb.12080] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The endoplasmic reticulum type I signal peptidase complex (ER SPC) is a conserved enzyme that cleaves the signal peptides of secretory or membrane preproteins. The deletion of this enzyme leads to the accumulation of uncleaved proteins in biomembranes and cell death. However, the physiological functions of ER SPC in insects are not fully understood. Here, a catalytic subunit gene of ER SPC, LmSPC1, was cloned from Locusta migratoria manilensis and its physiological functions were analysed by RNA interference (RNAi). The LmSPC1 open reading frame encoded a protein of 178 amino acids with all five conserved regions of signal peptidases. RNAi-mediated knockdown of LmSPC1 resulted in high mortality. Sixty-nine per cent of dead nymphs died of abnormal moulting, corresponding to decreased activity of moulting fluid protease. Moreover, insects in the RNAi group experienced a decline in food intake, and a decrease in the secretion of total protein and digestive enzymes from midgut tissues to the midgut lumen. Furthermore, the females produced fewer eggs and eggs with disrupted embryogenesis. These results indicate that LmSPC1 is required for the secretion of secretory proteins, affects physiological functions, including moulting, feeding, reproduction and embryonic development, and is essential for survival. Therefore, LmSPC1 may be a potential target for locust control.
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Affiliation(s)
- W Zhang
- Genetic Engineering Research Center, School of Life Science, Chongqing Engineering Research Center for Fungal Insecticide, The Key Laboratory of Gene Function and Expression Regulation, Chongqing University, Chongqing, China
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5
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Rao C V S, De Waelheyns E, Economou A, Anné J. Antibiotic targeting of the bacterial secretory pathway. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:1762-83. [PMID: 24534745 DOI: 10.1016/j.bbamcr.2014.02.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 01/27/2014] [Accepted: 02/06/2014] [Indexed: 02/06/2023]
Abstract
Finding new, effective antibiotics is a challenging research area driven by novel approaches required to tackle unconventional targets. In this review we focus on the bacterial protein secretion pathway as a target for eliminating or disarming pathogens. We discuss the latest developments in targeting the Sec-pathway for novel antibiotics focusing on two key components: SecA, the ATP-driven motor protein responsible for driving preproteins across the cytoplasmic membrane and the Type I signal peptidase that is responsible for the removal of the signal peptide allowing the release of the mature protein from the membrane. We take a bird's-eye view of other potential targets in the Sec-pathway as well as other Sec-dependent or Sec-independent protein secretion pathways as targets for the development of novel antibiotics. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey.
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Affiliation(s)
- Smitha Rao C V
- Laboratory of Molecular Bacteriology, Rega Institute, Department of Microbiology and Immunology, KU Leuven, O&N1, 6th floor, Herestraat 49, P.O. Box 1037, B-3000 Leuven, Belgium.
| | - Evelien De Waelheyns
- Laboratory of Molecular Bacteriology, Rega Institute, Department of Microbiology and Immunology, KU Leuven, O&N1, 6th floor, Herestraat 49, P.O. Box 1037, B-3000 Leuven, Belgium.
| | - Anastassios Economou
- Laboratory of Molecular Bacteriology, Rega Institute, Department of Microbiology and Immunology, KU Leuven, O&N1, 6th floor, Herestraat 49, P.O. Box 1037, B-3000 Leuven, Belgium; Institute of Molecular Biology and Biotechnology, FORTH, University of Crete, P.O. Box 1385, GR-711 10 Iraklio, Crete, Greece; Department of Biology, University of Crete, P.O. Box 1385, GR-71110 Iraklio, Crete, Greece.
| | - Jozef Anné
- Laboratory of Molecular Bacteriology, Rega Institute, Department of Microbiology and Immunology, KU Leuven, O&N1, 6th floor, Herestraat 49, P.O. Box 1037, B-3000 Leuven, Belgium.
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6
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Liu J, Smith PA, Steed DB, Romesberg F. Efforts toward broadening the spectrum of arylomycin antibiotic activity. Bioorg Med Chem Lett 2013; 23:5654-9. [PMID: 24012184 DOI: 10.1016/j.bmcl.2013.08.026] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 07/24/2013] [Accepted: 08/05/2013] [Indexed: 11/26/2022]
Abstract
New antibiotics are needed, and one source may be 'latent' antibiotics, natural products whose once broad-spectrum activity is currently limited by the evolution of resistance in nature. We have identified a potential class of latent antibiotics, the arylomycins, which are lipopeptides with a C-terminal macrocycle that target signal peptidase and whose spectrum is limited by a resistance-conferring mutation in many bacteria. Herein, we report the synthesis and evaluation of several arylomycin derivatives, and demonstrate that both C-terminal homologation with a glycyl aldehyde and addition of a positive charge to the macrocycle increase the activity and spectrum of the arylomycin scaffold.
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Affiliation(s)
- Jian Liu
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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7
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Liu L, Yang H, Shin HD, Chen RR, Li J, Du G, Chen J. How to achieve high-level expression of microbial enzymes: strategies and perspectives. Bioengineered 2013; 4:212-23. [PMID: 23686280 DOI: 10.4161/bioe.24761] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Microbial enzymes have been used in a large number of fields, such as chemical, agricultural and biopharmaceutical industries. The enzyme production rate and yield are the main factors to consider when choosing the appropriate expression system for the production of recombinant proteins. Recombinant enzymes have been expressed in bacteria (e.g., Escherichia coli, Bacillus and lactic acid bacteria), filamentous fungi (e.g., Aspergillus) and yeasts (e.g., Pichia pastoris). The favorable and very advantageous characteristics of these species have resulted in an increasing number of biotechnological applications. Bacterial hosts (e.g., E. coli) can be used to quickly and easily overexpress recombinant enzymes; however, bacterial systems cannot express very large proteins and proteins that require post-translational modifications. The main bacterial expression hosts, with the exception of lactic acid bacteria and filamentous fungi, can produce several toxins which are not compatible with the expression of recombinant enzymes in food and drugs. However, due to the multiplicity of the physiological impacts arising from high-level expression of genes encoding the enzymes and expression hosts, the goal of overproduction can hardly be achieved, and therefore, the yield of recombinant enzymes is limited. In this review, the recent strategies used for the high-level expression of microbial enzymes in the hosts mentioned above are summarized and the prospects are also discussed. We hope this review will contribute to the development of the enzyme-related research field.
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Affiliation(s)
- Long Liu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China
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8
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Pseudomonas aeruginosa possesses two putative type I signal peptidases, LepB and PA1303, each with distinct roles in physiology and virulence. J Bacteriol 2012; 194:4521-36. [PMID: 22730125 DOI: 10.1128/jb.06678-11] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Type I signal peptidases (SPases) cleave signal peptides from proteins during translocation across biological membranes and hence play a vital role in cellular physiology. SPase activity is also of fundamental importance to the pathogenesis of infection for many bacteria, including Pseudomonas aeruginosa, which utilizes a variety of secreted virulence factors, such as proteases and toxins. P. aeruginosa possesses two noncontiguous SPase homologues, LepB (PA0768) and PA1303, which share 43% amino acid identity. Reverse transcription (RT)-PCR showed that both proteases were expressed, while a FRET-based assay using a peptide based on the signal sequence cleavage region of the secreted LasB elastase showed that recombinant LepB and PA1303 enzymes were both active. LepB is positioned within a genetic locus that resembles the locus containing the extensively characterized SPase of E. coli and is of similar size and topology. It was also shown to be essential for viability and to have high sequence identity with SPases from other pseudomonads (≥ 78%). In contrast, PA1303, which is small for a Gram-negative SPase (20 kDa), was found to be dispensable. Mutation of PA1303 resulted in an altered protein secretion profile and increased N-butanoyl homoserine lactone production and influenced several quorum-sensing-controlled phenotypic traits, including swarming motility and the production of rhamnolipid and elastinolytic activity. The data indicate different cellular roles for these P. aeruginosa SPase paralogues; the role of PA1303 is integrated with the quorum-sensing cascade and includes the suppression of virulence factor secretion and virulence-associated phenotypes, while LepB is the primary SPase.
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9
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Ollinger J, O'Malley T, Ahn J, Odingo J, Parish T. Inhibition of the sole type I signal peptidase of Mycobacterium tuberculosis is bactericidal under replicating and nonreplicating conditions. J Bacteriol 2012; 194:2614-9. [PMID: 22427625 PMCID: PMC3347204 DOI: 10.1128/jb.00224-12] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 03/07/2012] [Indexed: 02/02/2023] Open
Abstract
Proteins secreted by bacteria perform functions vital for cell survival and play a role in virulence in Mycobacterium tuberculosis. M. tuberculosis lepB (Rv2903c) encodes the sole homolog of the type I signal peptidase (SPase). The lepB gene is essential in M. tuberculosis, since we could delete the chromosomal copy only when a second functional copy was provided elsewhere. By placing expression under the control of an anhydrotetracycline-inducible promoter, we confirmed that reduced lepB expression was detrimental to growth. Furthermore, we demonstrated that a serine-lysine catalytic dyad, characteristic for SPase function, is required for LepB function. We confirmed the involvement of LepB in the secretion of a reporter protein fused to an M. tuberculosis signal peptide. An inhibitor of LepB (MD3; a beta-aminoketone) was active against M. tuberculosis, exhibiting growth inhibition and bactericidal activity. Overexpression of lepB reduced the susceptibility of M. tuberculosis to MD3, and downregulation resulted in increased susceptibility, suggesting that LepB is the true target of MD3. MD3 lead to a rapid loss of viability and cell lysis. Interestingly, the compound had increased potency in nonreplicating cells, causing a reduction in viable cell numbers below the detection limit after 24 h. These data suggest that protein secretion is required to maintain viability under starvation conditions and that secreted proteins play a critical role in generating and surviving the persistent state. We conclude that LepB is a promising novel target for drug discovery in M. tuberculosis, since its inhibition results in rapid killing of persistent and replicating organisms.
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Affiliation(s)
- J Ollinger
- Infectious Disease Research Institute, Seattle, Washington, USA
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10
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Smitha Rao CV, Anné J. Bacterial type I signal peptidases as antibiotic targets. Future Microbiol 2012; 6:1279-96. [PMID: 22082289 DOI: 10.2217/fmb.11.109] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Despite an alarming increase in morbidity and mortality caused by multidrug-resistant bacteria, the number of antibiotics available to efficiently combat them is dwindling. Consequently, there is a pressing need for new drugs, preferably with novel modes of action to avert the problem of cross-resistance. Several new targets have been proposed, including proteins essential in the protein secretion pathway such as the type I signal peptidase (SPase), indispensable for the release of the signal peptide during secretion of Sec- and Tat-dependent proteins. The type I SPase is considered to be an attractive target because it is essential, substantially different from the eukaryotic counterpart, and its active site is located at the outer leaflet of the cytoplasmic membrane, permitting relatively easy access to potential inhibitors. A few SPase inhibitors have already been identified, but their suitability as drugs is yet to be confirmed. An overview is given on the currently known SPase inhibitors, how they can give valuable information on the structural, biochemical and target validation aspects of the SPases, the approaches to identify them, and their future potential as drugs.
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Affiliation(s)
- C V Smitha Rao
- Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, 3000 Leuven, Belgium
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11
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Auclair SM, Bhanu MK, Kendall DA. Signal peptidase I: cleaving the way to mature proteins. Protein Sci 2011; 21:13-25. [PMID: 22031009 DOI: 10.1002/pro.757] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 10/12/2011] [Accepted: 10/17/2011] [Indexed: 11/07/2022]
Abstract
Signal peptidase I (SPase I) is critical for the release of translocated preproteins from the membrane as they are transported from a cytoplasmic site of synthesis to extracytoplasmic locations. These proteins are synthesized with an amino-terminal extension, the signal sequence, which directs the preprotein to the Sec- or Tat-translocation pathway. Recent evidence indicates that the SPase I cleaves preproteins as they emerge from either pathway, though the steps involved are unclear. Now that the structure of many translocation pathway components has been elucidated, it is critical to determine how these components work in concert to support protein translocation and cleavage. Molecular modeling and NMR studies have provided insight on how the preprotein docks on SPase I in preparation for cleavage. This is a key area for future work since SPase I enzymes in a variety of species have now been identified and the inhibition of these enzymes by antibiotics is being pursued. The eubacterial SPase I is essential for cell viability and belongs to a unique group of serine endoproteases which utilize a Ser-Lys catalytic dyad instead of the prototypical Ser-His-Asp triad used by eukaryotes. As such, SPase I is a desirable antimicrobial target. Advances in our understanding of how the preprotein interfaces with SPase I during the final stages of translocation will facilitate future development of inhibitors that display a high efficacy against SPase I function.
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Affiliation(s)
- Sarah M Auclair
- Department of Pharmaceutical Sciences, The University of Connecticut, Storrs, CT 06269, USA
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12
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Hsu SC, Endow JK, Ruppel NJ, Roston RL, Baldwin AJ, Inoue K. Functional diversification of thylakoidal processing peptidases in Arabidopsis thaliana. PLoS One 2011; 6:e27258. [PMID: 22087276 PMCID: PMC3210150 DOI: 10.1371/journal.pone.0027258] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Accepted: 10/12/2011] [Indexed: 12/25/2022] Open
Abstract
Thylakoidal processing peptidase (TPP) is responsible for removing amino-terminal thylakoid-transfer signals from several proteins in the thylakoid lumen. Three TPP isoforms are encoded by the nuclear genome of Arabidopsis thaliana. Previous studies showed that one of them termed plastidic type I signal peptidase 1 (Plsp1) was necessary for processing three thylakoidal proteins and one protein in the chloroplast envelope in vivo. The lack of Plsp1 resulted in seedling lethality, apparently due to disruption of proper thylakoid development. The physiological roles of the other two TPP homologs remain unknown. Here we show that the three A. thaliana TPP isoforms evolved to acquire diverse functions. Phylogenetic analysis revealed that TPP may have originated before the endosymbiotic event, and that there are two groups of TPP in seed plants: one includes Plsp1 and another comprises the other two A. thaliana TPP homologs, which are named as Plsp2A and Plsp2B in this study. The duplication leading to the two groups predates the gymnosperm-angiosperm divergence, and the separation of Plsp2A and Plsp2B occurred after the Malvaceae-Brassicaceae diversification. Quantitative reverse transcription-PCR assay revealed that the two PLSP2 genes were co-expressed in both photosynthetic tissues and roots, whereas the PLSP1 transcript accumulated predominantly in photosynthetic tissues. Both PLSP2 genes were expressed in the aerial parts of the plsp1-null mutant at levels comparable to those in wild-type plants. The seedling-lethal phenotype of the plsp1-null mutant could be rescued by a constitutive expression of Plsp1 cDNA but not by that of Plsp2A or Plsp2B. These results indicate that Plsp1 and Plsp2 evolved to function differently, and that neither of the Plsp2 isoforms is necessary for proper thylakoid development in photosynthetic tissues.
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Affiliation(s)
- Shih-Chi Hsu
- Department of Plant Sciences, University of California Davis, Davis, California, United States of America
| | - Joshua K. Endow
- Department of Plant Sciences, University of California Davis, Davis, California, United States of America
| | - Nicholas J. Ruppel
- Department of Plant Sciences, University of California Davis, Davis, California, United States of America
| | - Rebecca L. Roston
- Department of Plant Sciences, University of California Davis, Davis, California, United States of America
| | - Amy J. Baldwin
- Department of Plant Sciences, University of California Davis, Davis, California, United States of America
| | - Kentaro Inoue
- Department of Plant Sciences, University of California Davis, Davis, California, United States of America
- * E-mail:
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13
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Broad-spectrum antibiotic activity of the arylomycin natural products is masked by natural target mutations. ACTA ACUST UNITED AC 2011; 17:1223-31. [PMID: 21095572 DOI: 10.1016/j.chembiol.2010.09.009] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Revised: 09/09/2010] [Accepted: 09/13/2010] [Indexed: 11/23/2022]
Abstract
Novel classes of broad-spectrum antibiotics are needed to treat multidrug-resistant pathogens. The arylomycin class of natural products inhibits a promising antimicrobial target, type I signal peptidase (SPase), but upon initial characterization appeared to lack whole-cell activity against most pathogens. Here, we show that Staphylococcus epidermidis, which is sensitive to the arylomycins, evolves resistance via mutations in SPase and that analogous mutations are responsible for the natural resistance of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. We identify diverse bacteria lacking these mutations and demonstrate that most are sensitive to the arylomycins. The results illustrate that the arylomycins have a broad-spectrum of activity and are viable candidates for development into therapeutics. The results also raise the possibility that naturally occurring resistance may have masked other natural product scaffolds that might be developed into therapeutics.
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14
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Sharma S, Pradhan A, Chauhan VS, Tuteja R. Isolation and characterization of type I signal peptidase of different malaria parasites. J Biomed Biotechnol 2010; 2005:301-9. [PMID: 16489263 PMCID: PMC1364540 DOI: 10.1155/jbb.2005.301] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Type I signal peptidases are important membrane-bound serine
proteases responsible for the cleavage of the signal peptide of
the proteins. These enzymes are unique serine proteases that
carry out catalysis using a serine/lysine catalytic dyad. In the
present study, we report the isolation of type I signal peptidase
from the malaria parasites Plasmodium falciparum,
Plasmodium knowlesi, and Plasmodium yoelii and
some characterization of type I signal peptidase of
Plasmodium falciparum. We show that these enzymes are
homologous to signal peptidases from various sources and also
contain the conserved boxes present in other type I signal
peptidases. The type I signal peptidase from P falciparum
is an intron-less and a single-copy gene. The results also show
that the enzyme from Plasmodium falciparum is subject to
self-cleavage and it has been demonstrated to possess type I
signal peptidase activity in E coli preprotein processing
in vivo by complementation assay. This study will be helpful in
understanding one of the important metabolic pathways “the
secretory pathway” in the parasite and should make an important
contribution in understanding the complex process of protein
targeting in the parasite.
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Affiliation(s)
- Sutikshan Sharma
- Malaria Group, International Centre for Genetic
Engineering and Biotechnology, PO Box 10504, Aruna Asaf Ali
Marg, New Delhi 110067, India
| | - Arun Pradhan
- Malaria Group, International Centre for Genetic
Engineering and Biotechnology, PO Box 10504, Aruna Asaf Ali
Marg, New Delhi 110067, India
| | - Virander S. Chauhan
- Malaria Group, International Centre for Genetic
Engineering and Biotechnology, PO Box 10504, Aruna Asaf Ali
Marg, New Delhi 110067, India
| | - Renu Tuteja
- Malaria Group, International Centre for Genetic
Engineering and Biotechnology, PO Box 10504, Aruna Asaf Ali
Marg, New Delhi 110067, India
- Renu Tuteja:
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15
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Shipman-Roston RL, Ruppel NJ, Damoc C, Phinney BS, Inoue K. The significance of protein maturation by plastidic type I signal peptidase 1 for thylakoid development in Arabidopsis chloroplasts. PLANT PHYSIOLOGY 2010; 152:1297-308. [PMID: 20097790 PMCID: PMC2832241 DOI: 10.1104/pp.109.151977] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2009] [Accepted: 01/19/2010] [Indexed: 05/20/2023]
Abstract
Thylakoids are the chloroplast internal membrane systems that house light-harvesting and electron transport reactions. Despite the important functions and well-studied constituents of thylakoids, the molecular mechanism of their development remains largely elusive. A recent genetic study has demonstrated that plastidic type I signal peptidase 1 (Plsp1) is vital for proper thylakoid development in Arabidopsis (Arabidopsis thaliana) chloroplasts. Plsp1 was also shown to be necessary for processing of an envelope protein, Toc75, and a thylakoid lumenal protein, OE33; however, the relevance of the protein maturation in both of the two distinct subcompartments for proper chloroplast development remained unknown. Here, we conducted an extensive analysis of the plsp1-null mutant to address the significance of lumenal protein maturation in thylakoid development. Plastids that lack Plsp1 were found to accumulate vesicles of variable sizes in the stroma. Analyses of the mutant plastids revealed that the lack of Plsp1 causes a reduction in accumulation of thylakoid proteins and that Plsp1 is involved in maturation of two additional lumenal proteins, OE23 and plastocyanin. Further immunoblotting and electron microscopy immunolocalization studies showed that OE33 associates with the stromal vesicles of the mutant plastids. Finally, we used a genetic complementation system to demonstrate that accumulation of improperly processed forms of Toc75 in the plastid envelope does not disrupt normal plant development. These results suggest that proper maturation of lumenal proteins may be a key process for correct assembly of thylakoids.
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16
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Geukens N, Rao C V S, Mellado RP, Frederix F, Reekmans G, De Keersmaeker S, Vrancken K, Bonroy K, Van Mellaert L, Lammertyn E, Anné J. Surface plasmon resonance-based interaction studies reveal competition of Streptomyces lividans type I signal peptidases for binding preproteins. Microbiology (Reading) 2006; 152:1441-1450. [PMID: 16622060 DOI: 10.1099/mic.0.28734-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Type I signal peptidases (SPases) are responsible for the cleavage of signal peptides from secretory proteins.Streptomyces lividanscontains four different SPases, denoted SipW, SipX, SipY and SipZ, having at least some differences in their substrate specificity. In this reportin vitropreprotein binding/processing and protein secretion in single SPase mutants was determined to gain more insight into the substrate specificity of the different SPases and the underlying molecular basis. Results indicated that preproteins do not preferentially bind to a particular SPase, suggesting SPase competition for binding preproteins. This observation, together with the fact that each SPase could process each preprotein tested with a similar efficiency in anin vitroassay, suggested that there is no real specificity in substrate binding and processing, and that they are all actively involved in preprotein processingin vivo. Although this seems to be the case for some proteins tested, high-level secretion of others was clearly dependent on only one particular SPase demonstrating clear differences in substrate preference at thein vivoprocessing level. Hence, these results strongly suggest that there are additional factors other than the cleavage requirements of the enzymes that strongly affect the substrate preference of SPasesin vivo.
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Affiliation(s)
- Nick Geukens
- Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium
| | - Smitha Rao C V
- Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium
| | - Rafael P Mellado
- Department of Microbial Biotechnology, Centro Nacional de Biotecnologia, Campus de la Universidad Autonoma, Cantoblanco, 28049 Madrid, Spain
| | | | | | - Sophie De Keersmaeker
- Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium
| | - Kristof Vrancken
- Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium
| | | | - Lieve Van Mellaert
- Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium
| | - Elke Lammertyn
- Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium
| | - Jozef Anné
- Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium
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17
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Tuteja R. Type I signal peptidase: An overview. Arch Biochem Biophys 2005; 441:107-11. [PMID: 16126156 DOI: 10.1016/j.abb.2005.07.013] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2005] [Accepted: 07/23/2005] [Indexed: 11/28/2022]
Abstract
The signal hypothesis suggests that proteins contain information within their amino acid sequences for protein targeting to the membrane. These distinct targeting sequences are cleaved by specific enzymes known as signal peptidases. There are various type of signal peptidases known such as type I, type II, and type IV. Type I signal peptidases are indispensable enzymes, which catalyze the cleavage of the amino-terminal signal-peptide sequences from preproteins, which are translocated across biological membranes. These enzymes belong to a novel group of serine proteases, which generally utilize a Ser-Lys or Ser-His catalytic dyad instead of the prototypical Ser-His-Asp triad. Despite having no distinct consensus sequence other than a commonly found 'Ala-X-Ala' motif preceding the cleavage site, signal sequences are recognized by type I signal peptidase with high fidelity. Type I signal peptidases have been found in bacteria, archaea, fungi, plants, and animals. In this review, I present an overview of bacterial type I signal peptidases and describe some of their properties in detail.
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Affiliation(s)
- Renu Tuteja
- International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067, India.
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18
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van Roosmalen ML, Geukens N, Jongbloed JDH, Tjalsma H, Dubois JYF, Bron S, van Dijl JM, Anné J. Type I signal peptidases of Gram-positive bacteria. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2005; 1694:279-97. [PMID: 15546672 DOI: 10.1016/j.bbamcr.2004.05.006] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2003] [Accepted: 05/12/2004] [Indexed: 11/21/2022]
Abstract
Proteins that are exported from the cytoplasm to the periplasm and outer membrane of Gram-negative bacteria, or the cell wall and growth medium of Gram-positive bacteria, are generally synthesized as precursors with a cleavable signal peptide. During or shortly after pre-protein translocation across the cytoplasmic membrane, the signal peptide is removed by signal peptidases. Importantly, pre-protein processing by signal peptidases is essential for bacterial growth and viability. This review is focused on the signal peptidases of Gram-positive bacteria, Bacillus and Streptomyces species in particular. Evolutionary concepts, current knowledge of the catalytic mechanism, substrate specificity requirements and structural aspects are addressed. As major insights in signal peptidase function and structure have been obtained from studies on the signal peptidase LepB of Escherichia coli, similarities and differences between this enzyme and known Gram-positive signal peptidases are highlighted. Notably, while the incentive for previous research on Gram-positive signal peptidases was largely based on their role in the biotechnologically important process of protein secretion, present-day interest in these essential enzymes is primarily derived from the idea that they may serve as targets for novel anti-microbials.
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Affiliation(s)
- Maarten L van Roosmalen
- Department of Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Kerklaan 30, 9751 NN Haren, Netherlands
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19
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Lammertyn E, Van Mellaert L, Meyen E, Lebeau I, De Buck E, Anné J, Geukens N. Molecular and functional characterization of type I signal peptidase from Legionella pneumophila. MICROBIOLOGY-SGM 2004; 150:1475-1483. [PMID: 15133109 DOI: 10.1099/mic.0.26973-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Legionella pneumophila is a facultative intracellular Gram-negative rod-shaped bacterium that has become an important cause of both community-acquired and nosocomial pneumonia. Numerous studies concerning the unravelling of the virulence mechanism of this important pathogen have been initiated. As evidence is now accumulating for the involvement of protein secretion systems in bacterial virulence in general, the type I signal peptidase (LepB) of L. pneumophila was of particular interest. This endopeptidase plays an essential role in the processing of preproteins carrying a typical amino-terminal signal peptide, upon translocation across the cytoplasmic membrane. This paper reports the cloning and the transcriptional analysis of the L. pneumophila lepB gene encoding the type I signal peptidase (SPase). Reverse transcription PCR experiments showed clear lepB expression when L. pneumophila was grown both in culture medium, and also intracellularly in Acanthamoeba castellanii, a natural eukaryotic host of L. pneumophila. In addition, LepB was shown to be encoded by a polycistronic mRNA transcript together with two other proteins, i.e. a LepA homologue and a ribonuclease III homologue. SPase activity of the LepB protein was demonstrated by in vivo complementation analysis in a temperature-sensitive Escherichia coli lepB mutant. Protein sequence and predicted membrane topology were compared to those of leader peptidases of other Gram-negative human pathogens. Most strikingly, a strictly conserved methionine residue in the substrate binding pocket was replaced by a leucine residue, which might influence substrate recognition. Finally it was shown by in vivo experiments that L. pneumophila LepB is a target for (5S,6S)-6-[(R)-acetoxyethyl]-penem-3-carboxylate, a specific inhibitor of type I SPases.
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Affiliation(s)
- Elke Lammertyn
- Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium
| | - Lieve Van Mellaert
- Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium
| | - Eef Meyen
- Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium
| | - Ilya Lebeau
- Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium
| | - Emmy De Buck
- Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium
| | - Jozef Anné
- Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium
| | - Nick Geukens
- Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium
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20
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Affiliation(s)
- Mark Paetzel
- Department of Chemistry, The Ohio State University, Columbus, Ohio 43210, USA
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21
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Zheng F, Angleton EL, Lu J, Peng SB. In vitro and in vivo self-cleavage of Streptococcus pneumoniae signal peptidase I. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:3969-77. [PMID: 12180973 DOI: 10.1046/j.1432-1033.2002.03083.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have previously demonstrated that Streptococcus pneumoniae signal peptidase (SPase) I catalyzes a self-cleavage to result in a truncated product, SPase37-204 [Peng, S.B., Wang, L., Moomaw, J., Peery, R.B., Sun, P.M., Johnson, R.B., Lu, J., Treadway, P., Skatrud, P.L. & Wang, Q.M. (2001) J. Bacteriol.183, 621-627]. In this study, we investigated the effect of phospholipid on invitro self-cleavage of S. pneumoniae SPase I. In the presence of phospholipid, the self-cleavage predominantly occurred at one cleavage site between Gly36-His37, whereas the self-cleavage occurred at multiple sites in the absence of phospholipid, and two additional self-cleavage sites, Ala65-His66 and Ala143-Phe144, were identified. All three self-cleavage sites strongly resemble the signal peptide cleavage site and follow the (-1, -3) rule for SPase I recognition. Kinetic analysis demonstrated that self-cleavage is a concentration dependent and intermolecular event, and the activity in the presence of phospholipid is 25-fold higher than that in the absence of phospholipid. Biochemical analysis demonstrated that SPase37-204, the major product of the self-cleavage totally lost activity to cleave its substrates, indicating that the self-cleavage resulted in the inactivation of the enzyme. More importantly, the self-cleavage was demonstrated to be happening in vivo in all the growth phases of S. pneumoniae cells. The bacterial cells keep the active SPase I at the highest level in exponential growth phase, suggesting that the self-cleavage may play an important role in regulating the activity of the enzyme under different conditions.
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Affiliation(s)
- Feng Zheng
- Infectious Diseases Research, Lilly Research Laboratories, Indianapolis, IN 46285, USA
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22
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Sharkov NA, Cai D. Discovery of substrate for type I signal peptidase SpsB from Staphylococcus aureus. J Biol Chem 2002; 277:5796-803. [PMID: 11741926 DOI: 10.1074/jbc.m106849200] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Based on the kinetic model of substrate phage proteolysis, we have formulated a strategy for best manipulating the conditions in screening phage display libraries for protease substrates (Sharkov, N. A., Davis, R. M., Reidhaar-Olson, J. F., Navre, M., and Cai, D. (2001) J. Biol. Chem. 276, 10788-10793). This strategy is exploited in the present study with signal peptidase SpsB from Staphylococcus aureus. We demonstrate that highly active substrate phage clones can be isolated from a phage display library by systematically tuning the selection stringency in screening. Several of the selected clones exhibit superior reactivity over a control, the best clone, SIIIRIII-8, showing >100-fold improvement. Because no conserved sequence features were readily revealed that could allow delineation of the active and unreactive clones, the sequences identified in five of the active clones were tested as synthetic dodecamers, Ac-AGX(8)GA-NH(2). Using electrospray ionization mass spectrometry, we show that four of these peptides can be cleaved by SpsB and that Ala is the P1 residue exclusively and Ala or Leu the P3 residue, in keeping with the (-3, -1) rule for substrate recognition by signal peptidase. Our successful screening with SpsB demonstrated the general applicability of the screening strategy and allowed us to isolate the first peptide substrates for the enzyme.
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23
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Bacterial Type I Signal Peptidases. ACTA ACUST UNITED AC 2002. [DOI: 10.1016/s1874-6047(02)80003-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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24
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Chu HH, Hoang V, Kreutzmann P, Hofemeister B, Melzer M, Hofemeister J. Identification and properties of type I-signal peptidases of Bacillus amyloliquefaciens. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:458-69. [PMID: 11856304 DOI: 10.1046/j.0014-2956.2001.02669.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The use of Bacillus amyloliquefaciens for enzyme production and its exceptional high protein export capacity initiated this study where the presence and function of multiple type I signal peptidase isoforms was investigated. In addition to type I signal peptidases SipS(ba) [Meijer, W.J.J., de Jong, A., Bea, G., Wisman, A., Tjalsma, H., Venema, G., Bron, S. & van Dijl, J.M. (1995) Mol. Microbiol. 17, 621-631] and SipT(ba) [Hoang, V. & Hofemeister, J. (1995) Biochim. Biophys. Acta 1269, 64-68] which were previously identified, here we present evidence for two other Sip-like genes in B. amyloliquefaciens. Same map positions as well as sequence motifs verified that these genes encode homologues of Bacillus subtilis SipV and SipW. SipU-encoding DNA was not found in B. amyloliquefaciens. SipW-encoding DNA was also found for other Bacillus strains representing different phylogenetic groups, but not for Bacillus stearothermophilus and Thermoactinomyces vulgaris. The absence of these genes, however, could have been overlooked due to sequence diversity. Sequence alignments of 23 known Sip-like proteins from Bacillus origin indicated further branching of the P-group signal peptidases into clusters represented by B. subtilis SipV, SipS-SipT-SipU and B. anthracis Sip3-Sip5 proteins, respectively. Each B. amyloliquefaciens sip(ba) gene was expressed in an Escherichia coli LepBts mutant and tested for genetic complementation of the temperature sensitive (TS) phenotype as well as pre-OmpA processing. Although SipS(ba) as well as SipT(ba) efficiently restored processing of pre-OmpA in E. coli, only SipS(ba) supported growth at TS conditions, indicating functional diversity. Changed properties of the sip(ba) gene disruption mutants, including cell autolysis, motility, sporulation, and nuclease activities, seemed to correlate with specificities and/or localization of B. amyloliquefaciens SipS, SipT and SipV isoforms.
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Affiliation(s)
- Hoang Ha Chu
- Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany
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25
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Lacks SA, Greenberg B. Constitutive competence for genetic transformation in Streptococcus pneumoniae caused by mutation of a transmembrane histidine kinase. Mol Microbiol 2001; 42:1035-45. [PMID: 11737645 DOI: 10.1046/j.1365-2958.2001.02697.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Competence for DNA uptake and genetic transformation in Streptococcus pneumoniae is regulated by a quorum-sensing system. A competence-stimulating polypeptide (CSP) is secreted by the bacteria and acts back on the cells via a transmembrane histidine kinase. This enzyme phosphorylates a response regulator that activates synthesis of a SigH-like protein. The new sigma factor enables expression of a set of proteins transcribed from a novel promoter. A mutation called trt had been found that circumvented this regulation. The mutant cells are constitutively competent; that is, they can be transformed at low cell densities, in the presence of proteases that attack CSP, or during growth at low pH. In this work, cells containing trt were shown to be competent even in the presence of a comAB mutation that blocks secretion of CSP. The trt mutation was localized to comD, the gene encoding the transmembrane histidine kinase. A DNA segment of the trt mutant corresponding to comCDE was cloned, and it was shown to contain the trt mutation by its ability to confer constitutive competence. A two-step assay, which was based on transfer of trt to a wild strain and screening for transformability in the presence of trypsin, served to locate the trt mutation precisely. It corresponds to a GC-->AT transition, which changes Asp299 in the histidine kinase to Asn. This alteration in the carboxyl terminal half of the protein, which is cytoplasmically located and contains the phosphorylase activity, presumably alters the enzyme conformation so that it is permanently activated, independent of signals from the transmembrane domain. These results may help illuminate the mechanism by which external signals affect kinase action in two-component regulatory systems, and they may be of practical value in facilitating genetic studies by rendering pneumococcal strains permanently competent.
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Affiliation(s)
- S A Lacks
- Department of Biology, Brookhaven National Laboratory, Upton, NY 11973, USA.
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26
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Peng SB, Zheng F, Angleton EL, Smiley D, Carpenter J, Scott JE. Development of an Internally Quenched Fluorescent Substrate and a Continuous Fluorimetric Assay for Streptococcus pneumoniae Signal Peptidase I. Anal Biochem 2001; 293:88-95. [PMID: 11373083 DOI: 10.1006/abio.2001.5102] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Signal peptidase (SPase) I is responsible for the cleavage of signal peptides of many secreted proteins in bacteria and serves as a potential target for the development of novel antibacterial agents due to its unique physiological and biochemical properties. In this paper, we describe a novel fluorogenic substrate, KLTFGTVK(Abz)PVQAIAGY(NO2)EWL, in which 2-aminobenzoic acid (Abz) and 3-nitrotyrosine (Y(NO2)) were used as the fluorescent donor and acceptor, respectively. The substrate can be cleaved by both Streptococcus pneumoniae and Escherichia coli SPase I. Upon cleavage of the fluorogenic substrate by SPase I, the fluorescent intensity increases and can be monitored continuously by spectrofluorometer. Kinetic analysis with S. pneumoniae SPase I demonstrated that the K(m) value for the substrate is 118.1 microM, and the k(cat) value is 0.032 s(-1). Mass spectrometric analysis and peptide sequencing of the two cleaved products confirmed that the cleavage occurs specifically at the predicted site. More interestingly, the positively charged lysine in the N-terminus of the substrate was demonstrated to be important for effective cleavage. Phospholipids were found to stimulate the cleavage reaction. This stimulation by phospholipids is dependent upon the N-terminal charge of the substrate, indicating that the interaction of the positively charged substrate with anionic phospholipids is important for maintaining the substrate in certain conformation for cleavage. The substrate and assay described here can be readily automated and utilized for the identification of potential antibacterial agents.
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Affiliation(s)
- S B Peng
- Infectious Diseases Research, Lilly Research Laboratories, Indianapolis, IN 46285, USA.
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27
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Peng SB, Wang L, Moomaw J, Peery RB, Sun PM, Johnson RB, Lu J, Treadway P, Skatrud PL, Wang QM. Biochemical characterization of signal peptidase I from gram-positive Streptococcus pneumoniae. J Bacteriol 2001; 183:621-7. [PMID: 11133956 PMCID: PMC94918 DOI: 10.1128/jb.183.2.621-627.2001] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2000] [Accepted: 10/25/2000] [Indexed: 11/20/2022] Open
Abstract
Bacterial signal peptidase I is responsible for proteolytic processing of the precursors of secreted proteins. The enzymes from gram-negative and -positive bacteria are different in structure and specificity. In this study, we have cloned, expressed, and purified the signal peptidase I of gram-positive Streptococcus pneumoniae. The precursor of streptokinase, an extracellular protein produced in pathogenic streptococci, was identified as a substrate of S. pneumoniae signal peptidase I. Phospholipids were found to stimulate the enzymatic activity. Mutagenetic analysis demonstrated that residues serine 38 and lysine 76 of S. pneumoniae signal peptidase I are critical for enzyme activity and involved in the active site to form a serine-lysine catalytic dyad, which is similar to LexA-like proteases and Escherichia coli signal peptidase I. Similar to LexA-like proteases, S. pneumoniae signal peptidase I catalyzes an intermolecular self-cleavage in vitro, and an internal cleavage site has been identified between glycine 36 and histidine 37. Sequence analysis revealed that the signal peptidase I and LexA-like proteases show sequence homology around the active sites and some common properties around the self-cleavage sites. All these data suggest that signal peptidase I and LexA-like proteases are closely related and belong to a novel class of serine proteases.
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Affiliation(s)
- S B Peng
- Infectious Diseases Research, Lilly Research Laboratories, Indianapolis, Indiana 46285, USA.
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28
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Carlos JL, Paetzel M, Brubaker G, Karla A, Ashwell CM, Lively MO, Cao G, Bullinger P, Dalbey RE. The role of the membrane-spanning domain of type I signal peptidases in substrate cleavage site selection. J Biol Chem 2000; 275:38813-22. [PMID: 10982814 DOI: 10.1074/jbc.m007093200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Type I signal peptidase (SPase I) catalyzes the cleavage of the amino-terminal signal sequences from preproteins destined for cell export. Preproteins contain a signal sequence with a positively charged n-region, a hydrophobic h-region, and a neutral but polar c-region. Despite having no distinct consensus sequence other than a commonly found c-region "Ala-X-Ala" motif preceding the cleavage site, signal sequences are recognized by SPase I with high fidelity. Remarkably, other potential Ala-X-Ala sites are not cleaved within the preprotein. One hypothesis is that the source of this fidelity is due to the anchoring of both the SPase I enzyme (by way of its transmembrane segment) and the preprotein substrate (by the h-region in the signal sequence) in the membrane. This limits the enzyme-substrate interactions such that cleavage occurs at only one site. In this work we have, for the first time, successfully isolated Bacillus subtilis type I signal peptidase (SipS) and a truncated version lacking the transmembrane domain (SipS-P2). With purified full-length as well as truncated constructs of both B. subtilis and Escherichia coli (Lep) SPase I, in vitro specificity studies indicate that the transmembrane domains of either enzyme are not important determinants of in vitro cleavage fidelity, since enzyme constructs lacking them reveal no alternate site processing of pro-OmpA nuclease A substrate. In addition, experiments with mutant pro-OmpA nuclease A substrate constructs indicate that the h-region of the signal peptide is also not critical for substrate specificity. In contrast, certain mutants in the c-region of the signal peptide result in alternate site cleavage by both Lep and SipS enzymes.
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Affiliation(s)
- J L Carlos
- Department of Chemistry, Ohio State University, Columbus, Ohio 43210, USA
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29
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Paetzel M, Dalbey RE, Strynadka NC. The structure and mechanism of bacterial type I signal peptidases. A novel antibiotic target. Pharmacol Ther 2000; 87:27-49. [PMID: 10924740 DOI: 10.1016/s0163-7258(00)00064-4] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Type I signal peptidases are essential membrane-bound serine proteases that function to cleave the amino-terminal signal peptide extension from proteins that are translocated across biological membranes. The bacterial signal peptidases are unique serine proteases that utilize a Ser/Lys catalytic dyad mechanism in place of the classical Ser/His/Asp catalytic triad mechanism. They represent a potential novel antibiotic target at the bacterial membrane surface. This review will discuss the bacterial signal peptidases that have been characterized to date, as well as putative signal peptidase sequences that have been recognized via bacterial genome sequencing. We review the investigations into the mechanism of Escherichia coli and Bacillus subtilis signal peptidase, and discuss the results in light of the recent crystal structure of the E. coli signal peptidase in complex with a beta-lactam-type inhibitor. The proposed conserved structural features of Type I signal peptidases give additional insight into the mechanism of this unique enzyme.
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Affiliation(s)
- M Paetzel
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
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