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A mortise-tenon joint in the transmembrane domain modulates autotransporter assembly into bacterial outer membranes. Nat Commun 2014; 5:4239. [PMID: 24967730 DOI: 10.1038/ncomms5239] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 05/28/2014] [Indexed: 11/08/2022] Open
Abstract
Bacterial autotransporters comprise a 12-stranded membrane-embedded β-barrel domain, which must be folded in a process that entraps segments of an N-terminal passenger domain. This first stage of autotransporter folding determines whether subsequent translocation can deliver the N-terminal domain to its functional form on the bacterial cell surface. Here, paired glycine-aromatic 'mortise and tenon' motifs are shown to join neighbouring β-strands in the C-terminal barrel domain, and mutations within these motifs slow the rate and extent of passenger domain translocation to the surface of bacterial cells. In line with this, biophysical studies of the autotransporter Pet show that the conserved residues significantly quicken completion of the folding reaction and promote stability of the autotransporter barrel domain. Comparative genomics demonstrate conservation of glycine-aromatic residue pairings through evolution as a previously unrecognized feature of all autotransporter proteins.
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Ben-Tekaya H, Gorvel JP, Dehio C. Bartonella and Brucella--weapons and strategies for stealth attack. Cold Spring Harb Perspect Med 2013; 3:3/8/a010231. [PMID: 23906880 DOI: 10.1101/cshperspect.a010231] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Bartonella spp. and Brucella spp. are closely related α-proteobacterial pathogens that by distinct stealth-attack strategies cause chronic infections in mammals including humans. Human infections manifest by a broad spectrum of clinical symptoms, ranging from mild to fatal disease. Both pathogens establish intracellular replication niches and subvert diverse pathways of the host's immune system. Several virulence factors allow them to adhere to, invade, proliferate, and persist within various host-cell types. In particular, type IV secretion systems (T4SS) represent essential virulence factors that transfer effector proteins tailored to recruit host components and modulate cellular processes to the benefit of the bacterial intruders. This article puts the remarkable features of these two pathogens into perspective, highlighting the mechanisms they use to hijack signaling and trafficking pathways of the host as the basis for their stealthy infection strategies.
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Affiliation(s)
- Houchaima Ben-Tekaya
- Focal Area Infection Biology, Biozentrum, University of Basel, 4052 Basel, Switzerland
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Hung MC, Christodoulides M. The biology of Neisseria adhesins. BIOLOGY 2013; 2:1054-109. [PMID: 24833056 PMCID: PMC3960869 DOI: 10.3390/biology2031054] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 07/01/2013] [Accepted: 07/03/2013] [Indexed: 01/15/2023]
Abstract
Members of the genus Neisseria include pathogens causing important human diseases such as meningitis, septicaemia, gonorrhoea and pelvic inflammatory disease syndrome. Neisseriae are found on the exposed epithelia of the upper respiratory tract and the urogenital tract. Colonisation of these exposed epithelia is dependent on a repertoire of diverse bacterial molecules, extending not only from the surface of the bacteria but also found within the outer membrane. During invasive disease, pathogenic Neisseriae also interact with immune effector cells, vascular endothelia and the meninges. Neisseria adhesion involves the interplay of these multiple surface factors and in this review we discuss the structure and function of these important molecules and the nature of the host cell receptors and mechanisms involved in their recognition. We also describe the current status for recently identified Neisseria adhesins. Understanding the biology of Neisseria adhesins has an impact not only on the development of new vaccines but also in revealing fundamental knowledge about human biology.
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Affiliation(s)
- Miao-Chiu Hung
- Neisseria Research, Molecular Microbiology, Clinical and Experimental Sciences, Sir Henry Wellcome Laboratories, Faculty of Medicine, University of Southampton, Southampton General Hospital, Southampton, SO16 6YD, UK.
| | - Myron Christodoulides
- Neisseria Research, Molecular Microbiology, Clinical and Experimental Sciences, Sir Henry Wellcome Laboratories, Faculty of Medicine, University of Southampton, Southampton General Hospital, Southampton, SO16 6YD, UK.
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Celik N, Webb CT, Leyton DL, Holt KE, Heinz E, Gorrell R, Kwok T, Naderer T, Strugnell RA, Speed TP, Teasdale RD, Likić VA, Lithgow T. A bioinformatic strategy for the detection, classification and analysis of bacterial autotransporters. PLoS One 2012; 7:e43245. [PMID: 22905239 PMCID: PMC3419190 DOI: 10.1371/journal.pone.0043245] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Accepted: 07/18/2012] [Indexed: 11/18/2022] Open
Abstract
Autotransporters are secreted proteins that are assembled into the outer membrane of bacterial cells. The passenger domains of autotransporters are crucial for bacterial pathogenesis, with some remaining attached to the bacterial surface while others are released by proteolysis. An enigma remains as to whether autotransporters should be considered a class of secretion system, or simply a class of substrate with peculiar requirements for their secretion. We sought to establish a sensitive search protocol that could identify and characterize diverse autotransporters from bacterial genome sequence data. The new sequence analysis pipeline identified more than 1500 autotransporter sequences from diverse bacteria, including numerous species of Chlamydiales and Fusobacteria as well as all classes of Proteobacteria. Interrogation of the proteins revealed that there are numerous classes of passenger domains beyond the known proteases, adhesins and esterases. In addition the barrel-domain-a characteristic feature of autotransporters-was found to be composed from seven conserved sequence segments that can be arranged in multiple ways in the tertiary structure of the assembled autotransporter. One of these conserved motifs overlays the targeting information required for autotransporters to reach the outer membrane. Another conserved and diagnostic motif maps to the linker region between the passenger domain and barrel-domain, indicating it as an important feature in the assembly of autotransporters.
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Affiliation(s)
- Nermin Celik
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
| | - Chaille T. Webb
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
| | - Denisse L. Leyton
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
- Department of Microbiology, Monash University, Clayton, Australia
| | - Kathryn E. Holt
- Department of Microbiology and Immunology, The University of Melbourne, Parkville, Australia
| | - Eva Heinz
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
| | - Rebecca Gorrell
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
- Department of Microbiology, Monash University, Clayton, Australia
| | - Terry Kwok
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
- Department of Microbiology, Monash University, Clayton, Australia
| | - Thomas Naderer
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
| | - Richard A. Strugnell
- Department of Microbiology and Immunology, The University of Melbourne, Parkville, Australia
| | - Terence P. Speed
- Bioinformatics Division, Walter and Eliza Hall Institute, Parkville, Australia
| | - Rohan D. Teasdale
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Australia
| | - Vladimir A. Likić
- The Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Australia
| | - Trevor Lithgow
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
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Kim KH, Aulakh S, Paetzel M. The bacterial outer membrane β-barrel assembly machinery. Protein Sci 2012; 21:751-68. [PMID: 22549918 DOI: 10.1002/pro.2069] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Accepted: 03/20/2012] [Indexed: 12/31/2022]
Abstract
β-Barrel proteins found in the outer membrane of Gram-negative bacteria serve a variety of cellular functions. Proper folding and assembly of these proteins are essential for the viability of bacteria and can also play an important role in virulence. The β-barrel assembly machinery (BAM) complex, which is responsible for the proper assembly of β-barrels into the outer membrane of Gram-negative bacteria, has been the focus of many recent studies. This review summarizes the significant progress that has been made toward understanding the structure and function of the bacterial BAM complex.
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Affiliation(s)
- Kelly H Kim
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
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