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Christodoulides M. Update on the Neisseria Macrophage Infectivity Potentiator-Like PPIase Protein. Front Cell Infect Microbiol 2022; 12:861489. [PMID: 35392612 PMCID: PMC8981591 DOI: 10.3389/fcimb.2022.861489] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 02/07/2022] [Indexed: 11/16/2022] Open
Abstract
Neisseria pathogens express a Macrophage Infectivity Potentiator Protein (MIP), which belongs to the FK506 binding protein (FKBP) family of proteins that exhibit peptidyl-prolyl cis/trans isomerase (PPIase) activity. Neisseria MIP proteins are potential candidates for inclusion into vaccines for gonorrhoea caused by N. gonorrhoeae infection, and meningitis/sepsis caused by M. meningitidis infection. Neisseria MIP proteins are also potential targets for directed drug treatments, although this remains relatively unexplored. In this mini-review, we provide an update into the vaccine potential of Neisseria MIP and the few published drug targeting studies, and explore further the diversity of this protein amongst both pathogenic and commensal Neisseria spp.
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Shafer WM, Datta A, Kumar Kolli V, Mahbubur Rahman M, Balthazar JT, Martin LE, Veal WL, Stephens DS, Carlson R. Phase variable changes in genes lgtA and lgtC within the lgtABCDE operon of Neisseria gonorrhoeae can modulate gonococcal susceptibility to normal human serum. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/09680519020080010501] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The α-chain of the core oligosaccharide of the lipo-oligosaccharide (LOS) produced by Neisseria gonorrhoeae can undergo reversible and rapid changes in structure due to phase-variable production of certain enzymes employed in the biosynthesis of the lacto- N-neotetraose structure. Five of these enzymes are encoded by the lgtABCDE operon, and polynucleotide tracts within three of these genes ( lgtA, lgtC and lgtD) can be substrates for slipped-strand mispairing events that lead to nucleotide insertions or deletion events which result in variable production of their respective gene products. We now report that phase-variable synthesis of the lgtA and lgtC gene products in strain FA19 results in the production of elongated LOS α-chains and that the presence of these LOS species can result in gonococci being sensitive to the bacteriolytic action of serum-antibody and complement. Hence, phase variation within the lgtABCDE operon can significantly impact the ability of gonococci to subvert this important host defense system.
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Affiliation(s)
- William M. Shafer
- Laboratories of Bacterial Pathogenesis, Veterans Affairs Medical Center (Atlanta), Decatur, Georgia USA, , Departments of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia, USA, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Anup Datta
- The Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, USA
| | - V.S. Kumar Kolli
- The Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, USA
| | - M. Mahbubur Rahman
- The Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, USA
| | - Jacqueline T. Balthazar
- Laboratories of Bacterial Pathogenesis, Veterans Affairs Medical Center (Atlanta), Decatur, Georgia USA, Departments of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Larry E. Martin
- Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Wendy L. Veal
- Departments of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - David S. Stephens
- Laboratories of Bacterial Pathogenesis, Veterans Affairs Medical Center (Atlanta), Decatur, Georgia USA, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Russell Carlson
- The Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, USA
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Humbert MV, Almonacid Mendoza HL, Jackson AC, Hung MC, Bielecka MK, Heckels JE, Christodoulides M. Vaccine potential of bacterial macrophage infectivity potentiator (MIP)-like peptidyl prolyl cis/trans isomerase (PPIase) proteins. Expert Rev Vaccines 2015; 14:1633-49. [PMID: 26468663 DOI: 10.1586/14760584.2015.1095638] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Peptidyl prolyl cis/trans isomerases (PPIases) are a superfamily of proteins ubiquitously distributed among living organisms, which function primarily to assist the folding and structuring of unfolded and partially folded polypeptide chains and proteins. In this review, we focus specifically on the Macrophage Infectivity Potentiator (MIP)-like PPIases, which are members of the immunophilin family of FK506-binding proteins (FKBP). MIP-like PPIases have accessory roles in virulence and are candidates for inclusion in vaccines protective against both animal and human bacterial pathogens. A structural vaccinology approach obviates any issues over molecular mimicry and potential cross-reactivity with human FKBP proteins and studies with a representative antigen, the Neisseria meningitidis-MIP, support this strategy. Moreover, a dual approach of vaccination and drug targeting could be considered for controlling bacterial infectious diseases of humans and animals.
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Affiliation(s)
- María Victoria Humbert
- a Neisseria Research, Molecular Microbiology, Academic Unit of Clinical and Experimental Sciences, Sir Henry Wellcome Laboratories , University of Southampton Faculty of Medicine , Southampton , UK
| | - Hannia L Almonacid Mendoza
- a Neisseria Research, Molecular Microbiology, Academic Unit of Clinical and Experimental Sciences, Sir Henry Wellcome Laboratories , University of Southampton Faculty of Medicine , Southampton , UK
| | - Alexandra C Jackson
- a Neisseria Research, Molecular Microbiology, Academic Unit of Clinical and Experimental Sciences, Sir Henry Wellcome Laboratories , University of Southampton Faculty of Medicine , Southampton , UK
| | - Miao-Chiu Hung
- a Neisseria Research, Molecular Microbiology, Academic Unit of Clinical and Experimental Sciences, Sir Henry Wellcome Laboratories , University of Southampton Faculty of Medicine , Southampton , UK
| | - Magdalena K Bielecka
- a Neisseria Research, Molecular Microbiology, Academic Unit of Clinical and Experimental Sciences, Sir Henry Wellcome Laboratories , University of Southampton Faculty of Medicine , Southampton , UK
| | - John E Heckels
- a Neisseria Research, Molecular Microbiology, Academic Unit of Clinical and Experimental Sciences, Sir Henry Wellcome Laboratories , University of Southampton Faculty of Medicine , Southampton , UK
| | - Myron Christodoulides
- a Neisseria Research, Molecular Microbiology, Academic Unit of Clinical and Experimental Sciences, Sir Henry Wellcome Laboratories , University of Southampton Faculty of Medicine , Southampton , UK
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Hollander A, Mercante AD, Shafer WM, Cornelissen CN. The iron-repressed, AraC-like regulator MpeR activates expression of fetA in Neisseria gonorrhoeae. Infect Immun 2011; 79:4764-76. [PMID: 21947770 PMCID: PMC3232672 DOI: 10.1128/iai.05806-11] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 09/05/2011] [Accepted: 09/13/2011] [Indexed: 12/23/2022] Open
Abstract
Neisseria gonorrhoeae is an obligate human pathogen that causes the common sexually transmitted infection gonorrhea. Gonococcal infections cause significant morbidity, particularly among women, as the organism ascends to the upper reproductive tract, resulting in pelvic inflammatory disease, ectopic pregnancy, and infertility. In the last few years, antibiotic resistance rates have risen dramatically, leading to severe restriction of treatment options for gonococcal disease. Gonococcal infections do not elicit protective immunity, nor is there an effective vaccine to prevent the disease. Thus, further understanding of the expression, function, and regulation of surface antigens could lead to better treatment and prevention modalities in the future. In the current study, we determined that an iron-repressed regulator, MpeR, interacted specifically with the DNA sequence upstream of fetA and activated FetA expression. Interestingly, MpeR was previously shown to regulate the expression of gonococcal antimicrobial efflux systems. We confirmed that the outer membrane transporter FetA allows gonococcal strain FA1090 to utilize the xenosiderophore ferric enterobactin as an iron source. However, we further demonstrated that FetA has an extended range of substrates that encompasses other catecholate xenosiderophores, including ferric salmochelin and the dimers and trimers of dihydroxybenzoylserine. We demonstrated that fetA is part of an iron-repressed, MpeR-activated operon which putatively encodes other iron transport proteins. This is the first study to describe a regulatory linkage between antimicrobial efflux and iron transport in N. gonorrhoeae. The regulatory nidus that links these systems, MpeR, is expressed exclusively by pathogenic neisseriae and is therefore expected to be an important virulence factor.
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Affiliation(s)
- Aimee Hollander
- Department of Microbiology, Virginia Commonwealth University Medical Center, Richmond, Virginia 23298
| | - Alexandra Dubon Mercante
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - William M. Shafer
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia 30322
- Laboratories of Bacterial Pathogenesis and Antimicrobial Resistance, VA Medical Center (Atlanta), Decatur, Georgia 30033
| | - Cynthia Nau Cornelissen
- Department of Microbiology, Virginia Commonwealth University Medical Center, Richmond, Virginia 23298
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Tett A, Spiers AJ, Crossman LC, Ager D, Ciric L, Dow JM, Fry JC, Harris D, Lilley A, Oliver A, Parkhill J, Quail MA, Rainey PB, Saunders NJ, Seeger K, Snyder LAS, Squares R, Thomas CM, Turner SL, Zhang XX, Field D, Bailey MJ. Sequence-based analysis of pQBR103; a representative of a unique, transfer-proficient mega plasmid resident in the microbial community of sugar beet. THE ISME JOURNAL 2007; 1:331-40. [PMID: 18043644 PMCID: PMC2656933 DOI: 10.1038/ismej.2007.47] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The plasmid pQBR103 was found within Pseudomonas populations colonizing the leaf and root surfaces of sugar beet plants growing at Wytham, Oxfordshire, UK. At 425 kb it is the largest self-transmissible plasmid yet sequenced from the phytosphere. It is known to enhance the competitive fitness of its host, and parts of the plasmid are known to be actively transcribed in the plant environment. Analysis of the complete sequence of this plasmid predicts a coding sequence (CDS)-rich genome containing 478 CDSs and an exceptional degree of genetic novelty; 80% of predicted coding sequences cannot be ascribed a function and 60% are orphans. Of those to which function could be assigned, 40% bore greatest similarity to sequences from Pseudomonas spp, and the majority of the remainder showed similarity to other gamma-proteobacterial genera and plasmids. pQBR103 has identifiable regions presumed responsible for replication and partitioning, but despite being tra+ lacks the full complement of any previously described conjugal transfer functions. The DNA sequence provided few insights into the functional significance of plant-induced transcriptional regions, but suggests that 14% of CDSs may be expressed (11 CDSs with functional annotation and 54 without), further highlighting the ecological importance of these novel CDSs. Comparative analysis indicates that pQBR103 shares significant regions of sequence with other plasmids isolated from sugar beet plants grown at the same geographic location. These plasmid sequences indicate there is more novelty in the mobile DNA pool accessible to phytosphere pseudomonas than is currently appreciated or understood.
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Affiliation(s)
- Adrian Tett
- Centre for Ecology and Hydrology-Oxford, Oxford, UK
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Hotopp JCD, Grifantini R, Kumar N, Tzeng YL, Fouts D, Frigimelica E, Draghi M, Giuliani MM, Rappuoli R, Stephens DS, Grandi G, Tettelin H. Comparative genomics of Neisseria meningitidis: core genome, islands of horizontal transfer and pathogen-specific genes. MICROBIOLOGY-SGM 2007; 152:3733-3749. [PMID: 17159225 DOI: 10.1099/mic.0.29261-0] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
To better understand Neisseria meningitidis genomes and virulence, microarray comparative genome hybridization (mCGH) data were collected from one Neisseria cinerea, two Neisseria lactamica, two Neisseria gonorrhoeae and 48 Neisseria meningitidis isolates. For N. meningitidis, these isolates are from diverse clonal complexes, invasive and carriage strains, and all major serogroups. The microarray platform represented N. meningitidis strains MC58, Z2491 and FAM18, and N. gonorrhoeae FA1090. By comparing hybridization data to genome sequences, the core N. meningitidis genome and insertions/deletions (e.g. capsule locus, type I secretion system) related to pathogenicity were identified, including further characterization of the capsule locus, bioinformatics analysis of a type I secretion system, and identification of some metabolic pathways associated with intracellular survival in pathogens. Hybridization data clustered meningococcal isolates from similar clonal complexes that were distinguished by the differential presence of six distinct islands of horizontal transfer. Several of these islands contained prophage or other mobile elements, including a novel prophage and a transposon carrying portions of a type I secretion system. Acquisition of some genetic islands appears to have occurred in multiple lineages, including transfer between N. lactamica and N. meningitidis. However, island acquisition occurs infrequently, such that the genomic-level relationship is not obscured within clonal complexes. The N. meningitidis genome is characterized by the horizontal acquisition of multiple genetic islands; the study of these islands reveals important sets of genes varying between isolates and likely to be related to pathogenicity.
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Affiliation(s)
| | - Renata Grifantini
- Novartis Vaccines and Diagnostics Ltd, Via Fiorentina 1, 53100 Siena, Italy
| | - Nikhil Kumar
- The Institute for Genomic Research, 9712 Medical Center Dr, Rockville, MD 20850, USA
| | - Yih Ling Tzeng
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia 30322 and Research Service, VA Medical Center, Decatur, GA 30033, USA
| | - Derrick Fouts
- The Institute for Genomic Research, 9712 Medical Center Dr, Rockville, MD 20850, USA
| | | | - Monia Draghi
- Novartis Vaccines and Diagnostics Ltd, Via Fiorentina 1, 53100 Siena, Italy
| | | | - Rino Rappuoli
- Novartis Vaccines and Diagnostics Ltd, Via Fiorentina 1, 53100 Siena, Italy
| | - David S Stephens
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia 30322 and Research Service, VA Medical Center, Decatur, GA 30033, USA
| | - Guido Grandi
- Novartis Vaccines and Diagnostics Ltd, Via Fiorentina 1, 53100 Siena, Italy
| | - Hervé Tettelin
- The Institute for Genomic Research, 9712 Medical Center Dr, Rockville, MD 20850, USA
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Snyder LAS, Saunders NJ. The majority of genes in the pathogenic Neisseria species are present in non-pathogenic Neisseria lactamica, including those designated as 'virulence genes'. BMC Genomics 2006; 7:128. [PMID: 16734888 PMCID: PMC1538595 DOI: 10.1186/1471-2164-7-128] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2006] [Accepted: 05/30/2006] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Neisseria meningitidis causes the life-threatening diseases meningococcal meningitis and meningococcal septicemia. Neisseria gonorrhoeae is closely related to the meningococcus, but is the cause of the very different infection, gonorrhea. A number of genes have been implicated in the virulence of these related yet distinct pathogens, but the genes that define and differentiate the species and their behaviours have not been established. Further, a related species, Neisseria lactamica is not associated with either type of infection in normally healthy people, and lives as a harmless commensal. We have determined which of the genes so far identified in the genome sequences of the pathogens are also present in this non-pathogenic related species. RESULTS Thirteen unrelated strains of N. lactamica were investigated using comparative genome hybridization to the pan-Neisseria microarray-v2, which contains 2845 unique gene probes. The presence of 127 'virulence genes' was specifically addressed; of these 85 are present in N. lactamica. Of the remaining 42 'virulence genes' only 11 are present in all four of the sequenced pathogenic Neisseria. CONCLUSION Assessment of the complete dataset revealed that the vast majority of genes present in the pathogens are also present in N. lactamica. Of the 1,473 probes to genes shared by all four pathogenic genome sequences, 1,373 hybridize to N. lactamica. These shared genes cannot include genes that are necessary and sufficient for the virulence of the pathogens, since N. lactamica does not share this behaviour. This provides an essential context for the interpretation of gene complement studies of the pathogens.
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Affiliation(s)
- Lori AS Snyder
- Bacterial Pathogenesis and Functional Genomics Group, Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK
| | - Nigel J Saunders
- Bacterial Pathogenesis and Functional Genomics Group, Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK
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Snyder LAS, Jarvis SA, Saunders NJ. Complete and variant forms of the 'gonococcal genetic island' in Neisseria meningitidis. MICROBIOLOGY-SGM 2006; 151:4005-4013. [PMID: 16339945 DOI: 10.1099/mic.0.27925-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Comparative genome hybridization using the pan-Neisseria microarray identified genes from the gonococcal genetic island (GGI) within Neisseria meningitidis strains of serogroups W-135, H, and Z. While some of these strains contain nearly all of the genes of the GGI, there are differences in the presence of some of these genes between the strains, including between those of the same serogroup. Attempts were then made to determine the location of the GGI in these meningococci. Sequencing of Neisseria gonorrhoeae strain MS11 revealed that the GGI is a conjugative plasmid that can be chromosomally integrated at the dif sites near ung and can also be present in its circularized form. In N. meningitidis, a dif site is present in this location and also serves as the point of chromosomal integration of the GGI in this species.
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Affiliation(s)
- Lori A S Snyder
- Bacterial Pathogenesis and Functional Genomics Group, Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
| | - Stephen A Jarvis
- Department of Computer Science, University of Warwick, Coventry CV4 7AL, UK
| | - Nigel J Saunders
- Bacterial Pathogenesis and Functional Genomics Group, Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
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Rouquette-Loughlin CE, Balthazar JT, Hill SA, Shafer WM. Modulation of the mtrCDE-encoded efflux pump gene complex of Neisseria meningitidis due to a Correia element insertion sequence. Mol Microbiol 2005; 54:731-41. [PMID: 15491363 DOI: 10.1111/j.1365-2958.2004.04299.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The mtr (multiple transferable resistance) gene complex in Neisseria gonorrhoeae encodes an energy-dependent efflux pump system that is responsible for export of anti-bacterial hydrophobic agents. Expression of the mtrCDE operon in gonococci is negatively regulated by the MtrR protein. Hydrophobic agent resistance mediated by the mtr system is also inducible, which results from an AraC-like protein termed MtrA. In this work, we identified and characterized a pump similar to the gonococcal mtr system in various strains of Neisseria meningitidis. Unlike the situation with gonococci, the mtr system in meningococci is not subject to the MtrR or MtrA regulatory schemes. An analysis of the promoter region of the mtrCDE operon in a panel of meningococcal strains revealed the presence of one or two classes of insertion sequence elements. A 155-159 bp insertion sequence element known as the Correia element, previously identified elsewhere in the gonococcal and meningococcal genomes, was present in the mtrCDE promoter region of all meningococcal strains tested. In addition to the Correia element, a minority of strains had a tandemly linked, intact copy of IS1301. As described previously, a binding site for the integration host factor (IHF) was present at the centre of the Correia element upstream of mtrCDE genes. IHF was found to bind specifically to this site and deletion of the IHF binding site enhanced mtrC transcription. We also identified a post-transcriptional regulation of the mtrCDE transcript by cleavage in the inverted repeat of the Correia element, as previously described by Mazzone et al. [Gene278: 211-222 (2001)] and De Gregorio et al. [Biochim Biophys Acta 1576: 39-44 (2002)]for other Correia element. We conclude that the mtr efflux system in meningococci is subject to transcriptional regulation by IHF and post-transcriptional regulation by cleavage in the inverted repeat of the Correia element.
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Jordan P, Snyder LAS, Saunders NJ. Diversity in coding tandem repeats in related Neisseria spp. BMC Microbiol 2003; 3:23. [PMID: 14611665 PMCID: PMC305346 DOI: 10.1186/1471-2180-3-23] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2003] [Accepted: 11/12/2003] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Tandem repeats contained within coding regions can mediate phase variation when the repeated units change the reading frame of the coding sequence in a copy number dependent manner. Coding tandem repeats are those which do not alter the reading frame with copy number, and the changes in copy number of these repeats may then potentially alter the function or antigenicity of the protein encoded. Three complete neisserial genomes were analyzed and compared to identify coding tandem repeats where the number of copies of the repeat will have some structural consequence for the protein. This is the first study to address coding tandem repeats that may affect protein structures using comparative genomics, combined with a population survey to investigate which show interstrain variability. RESULTS A total of 28 genes were identified. Of these, 22 contain coding tandem repeats that vary in copy number between the three sequenced strains, three strain specific genes were included for investigation on the basis of having >90% identity between repeated units, and three genes with repeated elements of >250 bp were included although no length variations were seen in the genomes. Amplification, and sequencing of repeats showing altered copy number, of these 28 coding tandem repeat containing regions, from a set of largely unrelated strains, revealed further repeat length variation in several cases. CONCLUSION Eighteen genes were identified which have variation in repeat copy number between strains of the same species, twelve of which show greater diversity in repeat copy number than is present in the sequenced genomes. In some cases, this may reflect a mechanism for the generation of antigenic variation, as previously described in other species. However, some of the genes identified encode proteins with cytoplasmic functions, including sugar metabolism, DNA repair, and protein production, in which repeat length variation may have other functions. Coding tandem repeats appear to represent a largely unexplored mechanism of generating diversity in the Neisseria spp.
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Affiliation(s)
- Philip Jordan
- Bacterial Pathogenesis and Functional Genomics Group, The Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford. OX1 3RE, UK
| | - Lori AS Snyder
- Bacterial Pathogenesis and Functional Genomics Group, The Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford. OX1 3RE, UK
| | - Nigel J Saunders
- Bacterial Pathogenesis and Functional Genomics Group, The Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford. OX1 3RE, UK
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Snyder LAS, Shafer WM, Saunders NJ. Divergence and transcriptional analysis of the division cell wall (dcw) gene cluster in Neisseria spp. Mol Microbiol 2003; 47:431-42. [PMID: 12519193 DOI: 10.1046/j.1365-2958.2003.03204.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Three of the 18 open reading frames in the division and cell wall synthesis cluster of the pathogenic Neisseria spp. are not present in the clusters of other bacterial species. The region containing two of these, dcaB and dcaC, displays interstrain and interspecies variability uncharacteristic of such clusters. 3' of dcaB is a Correia repeat enclosed element (CREE), which is only present in some strains. It has been suggested that this CREE is a transcriptional terminator, although we demonstrate otherwise. A gearbox-like promoter within this CREE is active in Escherichia coli but not in Neisseria meningitidis. There is an active promoter 5' of dcaC, although its sequence is not conserved. The presence of similarly located promoters has not been demonstrated in other species. In Neisseria lactamica, this promoter involves another dcw-associated CREE, the first demonstration of active promoter generation at the 5' end of this common intergenic, apparently mobile, element. Upstream of this promoter is an inverted pair of neisserial uptake signal sequences, which are commonly considered to be transcriptional terminators. It has been proposed to terminate transcription in this location, although we have demonstrated transcript extending through this uptake signal sequence. dcaC contains a 108 bp tandem repeat, which is present in different copy numbers in the neisserial strains examined. This investigation reveals extensive sequence variation, disputes the presence of transcriptional terminators and identifies active internal promoters in this normally highly conserved cluster of essential genes, and addresses the transcriptional activity of two common neisserial intergenic components.
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Affiliation(s)
- Lori A S Snyder
- The Sir William Dunn School of Pathology, Univrsity of Oxford, South Parks Road, Oxford OX1 3RE, UK.
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McGEE DJ, Coker C, Testerman TL, Harro JM, Gibson SV, Mobley HLT. The Helicobacter pylori flbA flagellar biosynthesis and regulatory gene is required for motility and virulence and modulates urease of H. pylori and Proteus mirabilis. J Med Microbiol 2002; 51:958-970. [PMID: 12448680 DOI: 10.1099/0022-1317-51-11-958] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Helicobacter pylori and Proteus mirabilis ureases are nickel-requiring metallo-enzymes that hydrolyse urea to NH3 and CO2. In both H. pylori and in an Escherichia coli model of H. pylori urease activity, a high affinity nickel transporter, NixA, is required for optimal urease activity, whereas the urea-dependent UreR positive transcriptional activator governs optimal urease expression in P. mirabilis. The H. pylori flbA gene is a flagellar biosynthesis and regulatory gene that modulates urease activity in the E. coli model of H. pylori urease activity. All flbA mutants of eight strains of H. pylori were non-motile and five had a strain-dependent alteration in urease activity. The flbA gene decreased urease activity 15-fold when expressed in E. coli containing the H. pylori urease locus and the nixA gene; this was reversed by disruption of flbA. The flbA gene decreased nixA transcription. flbA also decreased urease activity three-fold in E. coli containing the P. mirabilis urease locus in a urea- and UreR-dependent fashion. Here the flbA gene repressed the P. mirabilis urease promoter. Thus, FlbA decreased urease activity of both H. pylori and P. mirabilis, but through distinct mechanisms. H. pylori wild-type strain SS1 colonised gerbils at a mean of 5.4 x 10(6) cfu/g of antrum and caused chronic gastritis and lesions in the antrum. In contrast, the flbA mutant did not colonise five of six gerbils and caused no lesions, indicating that motility mediated by flbA was required for colonisation. Because FlbA regulates flagellar biosynthesis and secretion, as well as forming a structural component of the flagellar secretion apparatus, two seemingly unrelated virulence attributes, motility and urease, may be coupled in H. pylori and P. mirabilis and possibly also in other motile, ureolytic bacteria.
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Affiliation(s)
| | - Christopher Coker
- Departments of Microbiology & Immunology and †Comparative Medicine, University of South Alabama College of Medicine, Mobile, AL 36688 and *Department of Microbiology & Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | | | - Janette M Harro
- Departments of Microbiology & Immunology and †Comparative Medicine, University of South Alabama College of Medicine, Mobile, AL 36688 and *Department of Microbiology & Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Susan V Gibson
- Departments of Microbiology & Immunology and †Comparative Medicine, University of South Alabama College of Medicine, Mobile, AL 36688 and *Department of Microbiology & Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Harry L T Mobley
- Departments of Microbiology & Immunology and †Comparative Medicine, University of South Alabama College of Medicine, Mobile, AL 36688 and *Department of Microbiology & Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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Veal WL, Nicholas RA, Shafer WM. Overexpression of the MtrC-MtrD-MtrE efflux pump due to an mtrR mutation is required for chromosomally mediated penicillin resistance in Neisseria gonorrhoeae. J Bacteriol 2002; 184:5619-24. [PMID: 12270819 PMCID: PMC139619 DOI: 10.1128/jb.184.20.5619-5624.2002] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The importance of the mtrCDE-encoded efflux pump in conferring chromosomally mediated penicillin resistance on certain strains of Neisseria gonorrhoeae was determined by using genetic derivatives of penicillin-sensitive strain FA19 bearing defined mutations (mtrR, penA, and penB) donated by a clinical isolate (FA6140) expressing high-level resistance to penicillin and antimicrobial hydrophobic agents (HAs). When introduced into strain FA19 by transformation, a single base pair deletion in the mtrR promoter sequence from strain FA6140 was sufficient to provide high-level resistance to HAs (e.g., erythromycin and Triton X-100) but only a twofold increase in resistance to penicillin. When subsequent mutations in penA and porIB were introduced from strain FA6140 into strain WV30 (FA19 mtrR) by transformation, resistance to penicillin increased incrementally up to a MIC of 1.0 micro g/ml. Insertional inactivation of the gene (mtrD) encoding the membrane transporter component of the Mtr efflux pump in these transformant strains and in strain FA6140 decreased the MIC of penicillin by 16-fold. Genetic analyses revealed that mtrR mutations, such as the single base pair deletion in its promoter, are needed for phenotypic expression of penicillin and tetracycline resistance afforded by the penB mutation. As penB represents amino acid substitutions within the third loop of the outer membrane PorIB protein that modulate entry of penicillin and tetracycline, the results presented herein suggest that PorIB and the MtrC-MtrD-MtrE efflux pump act synergistically to confer resistance to these antibiotics.
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Affiliation(s)
- Wendy L Veal
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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14
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Tzeng YL, Datta A, Strole C, Kolli VSK, Birck MR, Taylor WP, Carlson RW, Woodard RW, Stephens DS. KpsF is the arabinose-5-phosphate isomerase required for 3-deoxy-D-manno-octulosonic acid biosynthesis and for both lipooligosaccharide assembly and capsular polysaccharide expression in Neisseria meningitidis. J Biol Chem 2002; 277:24103-13. [PMID: 11956197 DOI: 10.1074/jbc.m200931200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have identified and defined the function of kpsF of Neisseria meningitidis and the homologues of kpsF in encapsulated K1 and K5 Escherichia coli. KpsF was shown to be the arabinose-5-phosphate isomerase, an enzyme not previously identified in prokaryotes, that mediates the interconversion of ribulose 5-phosphate and arabinose 5-phosphate. KpsF is required for 3-deoxy-d-manno-octulosonic acid (Kdo) biosynthesis in N. meningitidis. Mutation of kpsF or the gene encoding the CMP-Kdo synthetase (kpsU/kdsB) in N. meningitidis resulted in expression of a lipooligosaccharide (LOS) structure that contained only lipid A and reduced capsule expression in the five invasive disease-associated meningococcal serogroups (A, B, C, Y, and W-135). The step linking meningococcal capsule and LOS biosynthesis was shown to be Kdo production as the expression of capsule was wild type in a Kdo transferase (kdtA) mutant. Thus, in addition to lipooligosaccharide assembly, Kdo is required for meningococcal capsular polysaccharide expression. Furthermore, N. meningitidis, unlike enteric Gram-negative bacteria, can survive and synthesize only unglycosylated lipid A.
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Affiliation(s)
- Yih-Ling Tzeng
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, the Department of Veterans Affairs Medical Center, Atlanta, Georgia 30033, USA
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15
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Rouquette-Loughlin C, Stojiljkovic I, Hrobowski T, Balthazar JT, Shafer WM. Inducible, but not constitutive, resistance of gonococci to hydrophobic agents due to the MtrC-MtrD-MtrE efflux pump requires TonB-ExbB-ExbD proteins. Antimicrob Agents Chemother 2002; 46:561-5. [PMID: 11796379 PMCID: PMC127027 DOI: 10.1128/aac.46.2.561-565.2002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The MtrC-MtrD-MtrE efflux pump possessed by Neisseria gonorrhoeae is very similar to the MexA-MexB-OprM efflux pump of Pseudomonas aeruginosa. Because the antimicrobial resistance property afforded by the MexA-MexB-OprM efflux pump also requires the TonB protein, we asked whether a similar requirement exists for the gonococcal efflux pump. Unlike earlier studies with P. aeruginosa, we found that constitutive levels of gonococcal resistance to hydrophobic antimicrobial agents (i.e., Triton X-100 [TX-100]) did not require the TonB, ExbB, or ExbD protein. However, inducible levels of TX-100 resistance in gonococci had an absolute requirement for the TonB-ExbB-ExbD system, suggesting that such resistance in gonococci has an energy requirement above and beyond that required for constitutive pump activity.
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Affiliation(s)
- Corinne Rouquette-Loughlin
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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16
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Nolan KJ, McGee DJ, Mitchell HM, Kolesnikow T, Harro JM, O'Rourke J, Wilson JE, Danon SJ, Moss ND, Mobley HLT, Lee A. In vivo behavior of a Helicobacter pylori SS1 nixA mutant with reduced urease activity. Infect Immun 2002; 70:685-91. [PMID: 11796600 PMCID: PMC127660 DOI: 10.1128/iai.70.2.685-691.2002] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Helicobacter pylori mutants devoid of urease activity fail to colonize the gastric mucosa of mice; however, the effect of decreased levels of urease on colonization has not been examined. The nixA gene, required for full urease activity, encodes a cytoplasmic membrane nickel transporter that imports nickel ions and leads to incorporation of nickel ions into apourease. A nixA mutant of the Sydney strain of H. pylori (SS1) was constructed by disruption of the nixA gene with a kanamycin resistance cassette. This mutant retained only half the urease activity of the wild-type (wild-type) SS1 strain. C57BL/6j (n = 75) and BALB/c (n = 75) mice were inoculated independently with the wild-type or the nixA strain. The level and distribution of colonization were assessed by bacterial colony counts and histological grading at 4, 12, and 24 weeks postinfection. Colonization levels of the nixA strain in BALB/c mice were significantly lower compared with SS1 (P = 0.005), while colonization in C57BL/6j mice was similar for both the wild-type and mutant strains. Subtle differences in colonization of the different regions of the stomach, determined by microscopic grading, were observed between wild-type SS1 and the nixA strain in BALB/c mice. On the contrary, when C57BL/6j (n = 35) and BALB/c (n = 35) mice were coinfected with the wild-type and nixA strains simultaneously, the nixA mutant failed to colonize and was outcompeted by the wild-type SS1 strain, which established normal levels of colonization. These results demonstrate the importance of the nixA gene for increasing the fitness of H. pylori for gastric colonization. Since nixA is required for full urease activity, the decreased fitness of the nixA mutant is likely due to reduced urease activity; however, pleiotropic effects of the mutation cannot be completely ruled out.
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Affiliation(s)
- Kylie J Nolan
- School of Microbiology and Immunology, The University of New South Wales, Australia
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17
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Kahler CM, Martin LE, Tzeng YL, Miller YK, Sharkey K, Stephens DS, Davies JK. Polymorphisms in Pilin Glycosylation Locus of
Neisseria meningitidis
Expressing Class II Pili. Infect Immun 2001; 69:3597-604. [PMID: 11349019 PMCID: PMC98345 DOI: 10.1128/iai.69.6.3597-3604.2001] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
ABSTRACT
We have located a locus,
pgl
, in
Neisseria meningitidis
strain NMB required for the glycosylation of class II pili. Between five and eight open reading frames (ORFs) (
pglF, pglB, pglC, pglB2, orf2, orf3, orf8
, and
avtA
) were present in the
pgl
clusters of different meningococcal isolates. The Class I pilus-expressing strains
Neisseria gonorrhoeae
MS11 and
N. meningitidis
MC58 each contain a
pgl
cluster in which
orf2
and
orf3
have been deleted. Strain NMB and other meningococcal isolates which express class II type IV pili contained
pgl
clusters in which
pglB
had been replaced by
pglB2
and an additional novel ORF,
orf8
, had been inserted between
pglB2
and
pglC
. Insertional inactivation of the eight ORFs of the
pgl
cluster of strain NMB showed that
pglF, pglB2, pglC
, and
pglD,
but not
orf2, orf3, orf8
, and
avtA
, were necessary for pilin glycosylation. Pilin glycosylation was not essential for resistance to normal human serum, as
pglF
and
pglD
mutants retained wild-type levels of serum resistance. Although
pglB2
and
pglC
mutants were significantly sensitive to normal human serum under the experimental conditions used, subsequent examination of the encapsulation phenotypes revealed that
pglB2
and
pglC
mutants expressed almost 50% less capsule than wild-type NMB. A mutation in
orf3
, which did not affect pilin glycosylation, also resulted in a 10% reduction in capsule expression and a moderately serum sensitive phenotype. On the basis of these results we suggest that pilin glycosylation may proceed via a lipid-linked oligosaccharide intermediate and that blockages in this pathway may interfere with capsular transport or assembly.
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Affiliation(s)
- C M Kahler
- Department of Microbiology, Monash University, Clayton, Australia.
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18
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Kahler CM, Blum E, Miller YK, Ryan D, Popovic T, Stephens DS. exl, an exchangeable genetic island in Neisseria meningitidis. Infect Immun 2001; 69:1687-96. [PMID: 11179344 PMCID: PMC98073 DOI: 10.1128/iai.69.3.1687-1696.2001] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The genetic structure and evolution of a novel exchangeable meningococcal genomic island was defined for the important human pathogen Neisseria meningitidis. In 125 meningococcal strains tested, one of three unrelated nucleotide sequences, designated exl (exchangeable locus), was found between a gene required for heme utilization, hemO, and col, encoding a putative Escherichia coli collagenase homologue. The 5' boundary of each exl cassette was the stop codon of hemO, whereas the 3' boundary was delineated by a 33-bp repeat containing neisserial uptake sequences located downstream of col. One of the three alternative exl cassettes contained the meningococcal hemoglobin receptor gene, hmbR (exl3). In other meningococcal strains, hmbR was absent from the genome and was replaced by either a nucleotide sequence containing a novel open reading frame, exl2, or a cassette containing exl3. The proteins encoded by exl2 and exl3 had no significant amino acid homology to HmbR but contained six motifs that are also present in the lipoprotein components of the lactoferrin (LbpB), transferrin (TbpB), and hemoglobin-haptoglobin (HpuA) uptake systems. To determine the evolutionary relationships among meningococci carrying hmbR, exl2, or exl3, isolates representing 92 electrophoretic types were examined. hmbR was found throughout the population structure of N. meningitidis (genetic distance, >0.425), whereas exl2 and exl3 were found in clonal groups at genetic distances of <0.2. The commensal neisserial species were identified as reservoirs for all of the exl cassettes found in meningococci. The structure of these cassettes and their correlation with clonal groups emphasize the extensive gene pool and frequent horizontal DNA transfer events that contribute to the evolution and virulence of N. meningitidis.
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Affiliation(s)
- C M Kahler
- Department of Medicine and Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia, USA.
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19
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Snyder LA, Saunders NJ, Shafer WM. A putatively phase variable gene (dca) required for natural competence in Neisseria gonorrhoeae but not Neisseria meningitidis is located within the division cell wall (dcw) gene cluster. J Bacteriol 2001; 183:1233-41. [PMID: 11157935 PMCID: PMC94996 DOI: 10.1128/jb.183.4.1233-1241.2001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2000] [Accepted: 11/14/2000] [Indexed: 11/20/2022] Open
Abstract
A cluster of 18 open reading frames (ORFs), 15 of which are homologous to genes involved in division and cell wall synthesis, has been identified in Neisseria gonorrhoeae and Neisseria meningitidis. The three additional ORFs, internal to the dcw cluster, are not homologous to dcw-related genes present in other bacterial species. Analysis of the N. meningitidis strain MC58 genome for foreign DNA suggests that these additional ORFs have not been acquired by recent horizontal exchange, indicating that they are a long-standing, integral part of the neisserial dcw gene cluster. Reverse transcription-PCR analysis of RNA extracted from N. gonorrhoeae strain FA19 confirmed that all three ORFs are transcribed in gonococci. One of these ORFs (dca, for division cluster competence associated), located between murE and murF, was studied in detail and found to be essential for competence in the gonococcal but not in the meningococcal strains tested. Computer analysis predicts that dca encodes an inner membrane protein similar to hypothetical proteins produced by other gram-negative bacteria. In some meningococcal strains dca is prematurely terminated following a homopolymeric tract of G's, the length of which differs between isolates of N. meningitidis, suggesting that dca is phase variable in this species. A deletion and insertional mutation was made in the dca gene of N. gonorrhoeae strain FA19 and N. meningitidis strain NMB. This mutation abrogated the ability of the gonococci to be transformed with chromosomal DNA. Thus, we conclude that the dca-encoded gene product is an essential competence factor for gonococci.
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Affiliation(s)
- L A Snyder
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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20
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Meyer F, Wilson KT, James SP. Modulation of innate cytokine responses by products of Helicobacter pylori. Infect Immun 2000; 68:6265-72. [PMID: 11035734 PMCID: PMC97708 DOI: 10.1128/iai.68.11.6265-6272.2000] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The gastric inflammatory and immune response in Helicobacter pylori infection may be due to the effect of different H. pylori products on innate immune mechanisms. The aim of this study was to determine whether bacterial components could modulate cytokine production in vitro and thus contribute to Th1 polarization of the gastric immune response observed in vivo. The effect of H. pylori recombinant urease, bacterial lysate, intact bacteria, and bacterial DNA on proliferation and cytokine production by peripheral blood mononuclear cells (PBMCs) from H. pylori-negative donors was examined as a model for innate cytokine responses. Each of the different H. pylori preparations induced gamma interferon (IFN-gamma) and interleukin-12p40 (IL-12p40), but not IL-2 or IL-5, production, and all but H. pylori DNA stimulated release of IL-10. Addition of anti-IL-12 antibody to cultures partially inhibited IFN-gamma production. In addition, each bacterial product inhibited mitogen-stimulated IL-2 production by PBMCs and Jurkat T cells. The inhibitory effect of bacterial products on IL-2 production correlated with inhibition of mitogen-stimulated lymphocyte proliferation, although urease inhibited IL-2 production without inhibiting proliferation, suggesting that inhibition of IL-2 production alone is not sufficient to inhibit lymphocyte proliferation. The results of these studies demonstrate that Th1 polarization of the gastric immune response may be due in part to the direct effects of multiple different H. pylori components that enhance IFN-gamma and IL-12 production while inhibiting both IL-2 production and cell proliferation that may be necessary for Th2 responses.
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Affiliation(s)
- F Meyer
- Division of Gastroenterology, Department of Medicine, University of Maryland, Baltimore, Maryland 21201, USA
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21
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Abstract
Neisseria meningitidis, an exclusive pathogen of humans, remains the leading worldwide cause of meningitis and fatal sepsis, usually in otherwise healthy individuals. In recent years, significant advances have improved our understanding of the epidemiology and genetic basis of meningococcal disease and led to progress in the development of the next generation of meningococcal vaccines. This review summarizes current knowledge of the human susceptibility to and the epidemiology and molecular pathogenesis of meningococcal disease.
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Affiliation(s)
- Y L Tzeng
- Department of Medicine and Microbiology, Emory University School of Medicine, Veterans Affairs Medical Center, Georgia, Atlanta, USA
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22
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McGee DJ, Radcliff FJ, Mendz GL, Ferrero RL, Mobley HL. Helicobacter pylori rocF is required for arginase activity and acid protection in vitro but is not essential for colonization of mice or for urease activity. J Bacteriol 1999; 181:7314-22. [PMID: 10572136 PMCID: PMC103695 DOI: 10.1128/jb.181.23.7314-7322.1999] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Arginase of the Helicobacter pylori urea cycle hydrolyzes L-arginine to L-ornithine and urea. H. pylori urease hydrolyzes urea to carbon dioxide and ammonium, which neutralizes acid. Both enzymes are involved in H. pylori nitrogen metabolism. The roles of arginase in the physiology of H. pylori were investigated in vitro and in vivo, since arginase in H. pylori is metabolically upstream of urease and urease is known to be required for colonization of animal models by the bacterium. The H. pylori gene hp1399, which is orthologous to the Bacillus subtilis rocF gene encoding arginase, was cloned, and isogenic allelic exchange mutants of three H. pylori strains were made by using two different constructs: 236-2 and rocF::aphA3. In contrast to wild-type (WT) strains, all rocF mutants were devoid of arginase activity and had diminished serine dehydratase activity, an enzyme activity which generates ammonium. Compared with WT strain 26695 of H. pylori, the rocF::aphA3 mutant was approximately 1, 000-fold more sensitive to acid exposure. The acid sensitivity of the rocF::aphA3 mutant was not reversed by the addition of L-arginine, in contrast to the WT, and yielded a approximately 10, 000-fold difference in viability. Urease activity was similar in both strains and both survived acid exposure equally well when exogenous urea was added, indicating that rocF is not required for urease activity in vitro. Finally, H. pylori mouse-adapted strain SS1 and the 236-2 rocF isogenic mutant colonized mice equally well: 8 of 9 versus 9 of 11 mice, respectively. However, the rocF::aphA3 mutant of strain SS1 had moderately reduced colonization (4 of 10 mice). The geometric mean levels of H. pylori recovered from these mice (in log(10) CFU) were 6.1, 5.5, and 4.1, respectively. Thus, H. pylori rocF is required for arginase activity and is crucial for acid protection in vitro but is not essential for in vivo colonization of mice or for urease activity.
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Affiliation(s)
- D J McGee
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
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23
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Zarantonelli L, Borthagaray G, Lee EH, Shafer WM. Decreased azithromycin susceptibility of Neisseria gonorrhoeae due to mtrR mutations. Antimicrob Agents Chemother 1999; 43:2468-72. [PMID: 10508026 PMCID: PMC89502 DOI: 10.1128/aac.43.10.2468] [Citation(s) in RCA: 113] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Single-dose azithromycin therapy has recently been used in Uruguay for the treatment of uncomplicated gonococcal infections. As part of an active surveillance study to monitor the emergence of antibiotic resistance in gonococcal isolates, we examined the levels of azithromycin susceptibility in 51 consecutive isolates obtained from males with uncomplicated gonococcal urethritis. Isolates with decreased susceptibility to azithromycin (MICs, 0.25 to 0.5 microg/ml) were common, and these isolates often displayed cross-resistance to hydrophobic antimicrobial agents (erythromycin and Triton X-100). Resistance to erythromycin and Triton X-100 is frequently due to overexpression of the mtrCDE-encoded efflux pump mediated by mutations in the mtrR gene, which encodes a transcriptional repressor that modulates expression of the mtrCDE operon. Accordingly, we questioned whether clinical isolates that express decreased azithromycin susceptibility harbor mtrR mutations. Promoter mutations that would decrease the level of expression of mtrR as well as a missense mutation at codon 45 in the mtrR-coding region that would result in a radical amino acid replacement within the DNA-binding motif of MtrR were found in these strains. When these mutations were transferred into azithromycin-susceptible strain FA19 by transformation, the susceptibility of gonococci to azithromycin was decreased by nearly 10-fold. The mtrCDE-encoded efflux pump system was responsible for this property since insertional inactivation of the mtrC gene resulted in enhanced susceptibility of gonococci to azithromycin. We conclude that the mtrCDE-encoded efflux pump can recognize azithromycin and that the emergence of gonococcal strains with decreased susceptibility to azithromycin can, in part, be explained by mtrR mutations.
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Affiliation(s)
- L Zarantonelli
- National Center for Gonococcal Antimicrobial Susceptibility Surveillance, Department of Microbiology, School of Chemistry, Montevideo, 11800, Uruguay
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24
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Rouquette C, Harmon JB, Shafer WM. Induction of the mtrCDE-encoded efflux pump system of Neisseria gonorrhoeae requires MtrA, an AraC-like protein. Mol Microbiol 1999; 33:651-8. [PMID: 10417654 DOI: 10.1046/j.1365-2958.1999.01517.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The mtr (multiple transferable resistance) gene complex in Neisseria gonorrhoeae encodes an energy-dependent efflux pump composed of the MtrC-MtrD-MtrE cell envelope proteins that serves to export structurally diverse antimicrobial, hydrophobic agents (HAs). Many of these agents have membrane-acting detergent activity. Using Triton X-100 (TX-100) as a representative HA, we found that the mtrCDE efflux pump operon could be induced to higher levels of expression when an HA-sensitive strain was exposed to sublethal concentrations of this non-ionic detergent and the structurally related spermicide, nonoxynol-9. This induction was at the level of mtrCDE gene transcription and was independent of the MtrR repressor, which normally decreases mtrCDE gene expression. However, the enhanced resistance of gonococci to TX-100 was dependent on the expression of a previously undescribed gonococcal protein that belonged to the AraC/XylS family of transcriptional activators. We have termed this protein MtrA to signify its likely role in the activation of mtrCDE gene expression. Taken together with previous studies dealing with the genetic control of mtrCDE gene expression, we propose that gonococci can modulate their resistance to HAs through both positive and negative transcriptional control processes. The action of these regulatory processes is probably of importance in determining the survival capacity of gonococci at mucosal surfaces that contain detergent-like HAs.
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Affiliation(s)
- C Rouquette
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA 30322, USA
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25
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Lee EH, Shafer WM. The farAB-encoded efflux pump mediates resistance of gonococci to long-chained antibacterial fatty acids. Mol Microbiol 1999; 33:839-45. [PMID: 10447892 DOI: 10.1046/j.1365-2958.1999.01530.x] [Citation(s) in RCA: 123] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Gonococci often infect mucosal surfaces bathed in antibacterial fatty acids (FAs). Resistance of gonococci to FAs and other antibacterial hydrophobic agents has been attributed to the mtrCDE-encoded efflux pump system and a heretofore undefined mechanism. This alternative resistance mechanism has been suggested to mediate gonococcal resistance to long-chained FAs independently of the mtr efflux pump. We have now identified this alternative FA resistance system in gonococci and report that it bears significant similarity to the emrAB-encoded efflux pump possessed by Escherichia coli and the vceAB-encoded pump of Vibrio cholerae. We termed the gonococcal version of this efflux pump farAB (fatty acid resistance) to signify its involvement in FA resistance expressed by gonococci and to distinguish it from the emrAB- or vceAB-encoded pumps that modulate bacterial susceptibility to uncoupling agents and certain antibiotics. Although the farAB system in gonococci was found to provide resistance to FAs independently of the mtrCDE-encoded efflux pump, its function was dependent on the MtrE outer membrane protein. Moreover, expression of the tandemly linked farA and farB genes was positively associated with the presence of the MtrR transcriptional regulatory protein that normally downregulates the expression of mtrCDE. Thus, the data presented herein suggest that, while the mtrCDE- and farAB-encoded systems act independently to mediate resistance of gonococci to host-derived, hydrophobic antimicrobial agents, their capacity to export these agents is dependent on the same outer membrane protein (MtrE), and their expression may be differentially controlled by the same transcriptional regulatory protein (MtrR).
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Affiliation(s)
- E H Lee
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA 30322, USA
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26
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Mo YY, Seshu J, Wang D, Mallavia LP. Synthesis in Escherichia coli of two smaller enzymically active analogues of Coxiella burnetii macrophage infectivity potentiator (CbMip) protein utilizing a single open reading frame from the cbmip gene. Biochem J 1998; 335 ( Pt 1):67-77. [PMID: 9742214 PMCID: PMC1219753 DOI: 10.1042/bj3350067] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
FK506-binding proteins (FKBPs) have been identified in a variety of eukaryotic and prokaryotic organisms. Macrophage infectivity potentiator (CbMip, 23.5 kDa) protein of the obligate intracellular bacterium, Coxiella burnetii, was shown previously to belong to the family of FKBPs based on sequence homology and peptidyl-prolyl cis/trans isomerase (PPIase) activity. Further characterization of the cbmip gene has identified two additional proteins with molecular masses of 15.5 and 15.0 kDa that are synthesized, in addition to the 23.5 kDa CbMip, when expressed in Escherichia coli. Amino acid sequencing at the N-terminus combined with transcription and translation fusion expression revealed that the two proteins were synthesized from the same open reading frame of the cbmip gene, but starting at different internal translation start codons, probably by translational reinitiation. When the internal methionines serving as start sites were replaced with lysine by site-directed mutagenesis, the synthesis of 15.5 and 15.0 kDa proteins was abolished even though the synthesis of 23.5 kDa CbMip was intact. This confirmed that the 15.5 and 15.0 kDa proteins are indeed generated by translational reinitiation and are not degradation products of the 23.5 kDa protein. Like other FKBPs, both 15.5 and 15.0 kDa proteins exhibit PPIase activity. Because they share significant sequence homology with FKBPs and have a similar PPIase activity, 15.5 and 15. 0 kDa proteins are designated as C. burnetii FKBP (Cb-FKBP) analogues I and II, respectively. TnphoA mutagenesis demonstrated that whereas the large protein (CbMip) is secreted, Cb-FKBP analogues I and II are cytoplasmic, indicating that structural variations could allow for different subcellular compartmentalization of similar proteins. Western-blot analysis of lysates of purified C. burnetii using a CbMip-specific monoclonal antibody revealed the presence of a protein migrating at approximately 15 kDa, indicating the presence of smaller Cb-FKBP analogue(s) in C. burnetii, although at much lower levels compared with 23.5 kDa CbMip. This unique gene organization seen with cbmip may provide the organism with a mechanism of efficient use of its limited genetic information to synthesize proteins that are structurally different yet functionally similar.
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Affiliation(s)
- Y Y Mo
- Department of Microbiology, Washington State University, Pullman, WA 99164-4233, USA
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27
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Veal WL, Yellen A, Balthazar JT, Pan W, Spratt BG, Shafer WM. Loss-of-function mutations in the mtr efflux system of Neisseria gonorrhoeae. MICROBIOLOGY (READING, ENGLAND) 1998; 144 ( Pt 3):621-627. [PMID: 9534233 DOI: 10.1099/00221287-144-3-621] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Resistance of Neisseria gonorrhoeae to antimicrobial hydrophobic agents (HAs) has been ascribed to the mtr (multiple transferable resistance) operon. This operon is composed of the mtrR gene, which encodes a transcriptional repressor (MtrR), and a three-gene complex (mtrCDE), which encodes cell envelope proteins (MtrC-MtrD-MtrE) that form an energy-dependent efflux pump. HA-hypersusceptible strains are often isolated from patients, but the genetic basis for such hypersusceptibility was heretofore unknown. The genetic basis of HA hypersusceptibility in laboratory-derived strains BR54 and BR87 was studied to learn if this trait could be linked to mutations in the mtr operon. Mutations in the mtrR gene of these strains that could be phenotypically suppressed by mutations in their mtrC or mtrD genes were identified. Thus, small deletions (4-10 bp) in the mtrC or mtrD genes of strains BR87 and BR54 that would result in the production of truncated efflux pump proteins that serve as a membrane fusion protein (MtrC) or transporter of HAs (MtrD) were found to be responsible for their HA-hypersusceptible property.
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Affiliation(s)
- Wendy L Veal
- Department of Microbiology and Immunology, Emory University School of Medicine,Atlanta, GA 30322, USA
| | - Ansley Yellen
- Department of Microbiology and Immunology, Emory University School of Medicine,Atlanta, GA 30322, USA
| | - Jacqueline T Balthazar
- Laboratories of Microbial Pathogenesis, Medical Research Service, VA Medical Center (Atlanta),Decatur, GA 30033,USA
- Department of Microbiology and Immunology, Emory University School of Medicine,Atlanta, GA 30322, USA
| | - Wubin Pan
- Microbial Genetics Group, School of Biological Sciences, University of Sussex,Falmer, Brighton BN1 9QG,UK
| | - Brian G Spratt
- Microbial Genetics Group, School of Biological Sciences, University of Sussex,Falmer, Brighton BN1 9QG,UK
| | - William M Shafer
- Laboratories of Microbial Pathogenesis, Medical Research Service, VA Medical Center (Atlanta),Decatur, GA 30033,USA
- Department of Microbiology and Immunology, Emory University School of Medicine,Atlanta, GA 30322, USA
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Pissavin C, Hugouvieux-Cotte-Pattat N. Characterization of a periplasmic peptidyl-prolyl cis-trans isomerase in Erwinia chrysanthemi. FEMS Microbiol Lett 1997; 157:59-65. [PMID: 9418240 DOI: 10.1111/j.1574-6968.1997.tb12753.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The main determinant of the plant pathogen Erwinia chrysanthemi virulence is the production of extracellular enzymes, mainly pectate lyases. Adjacent to a pectate lyase encoding locus, we identified the gene rotA supposed to encode a folding catalyst. Overproduction of the protein and assay of activity using a synthetic substrate, confirmed that rotA encodes a periplasmic peptidyl-prolyl cis-trans isomerase. rotA disruption provokes no change in cell morphology, cell viability, growth rate or stability of the extracellular and periplasmic proteins. In addition, this mutation does not alter the activity of the pectate lyases, their stability in the periplasm during the transitory step of secretion or their recognition by the Out secretory system. rotA expression was followed using a rotA::uidA transcriptional fusion. Some environmental conditions, such as temperature variations and nitrogen starvation, modulate rotA expression. In contrast to the E. coli rotA gene, the E. chrysanthemi rotA possesses only one promoter and is not controlled by the CRP global regulator.
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Affiliation(s)
- C Pissavin
- Laboratoire de Génétique Moléculaire des Microorganismes et des Interactions Cellulaires, CNRS-UMR 5577, INSA de Lyon, Villeurbanne, France.
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29
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Hagman KE, Lucas CE, Balthazar JT, Snyder L, Nilles M, Judd RC, Shafer WM. The MtrD protein of Neisseria gonorrhoeae is a member of the resistance/nodulation/division protein family constituting part of an efflux system. MICROBIOLOGY (READING, ENGLAND) 1997; 143 ( Pt 7):2117-2125. [PMID: 9245801 DOI: 10.1099/00221287-143-7-2117] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The mtr (multiple transferable resistance) system of Neisseria gonorrhoeae mediates resistance of gonococci to structurally diverse hydrophobic agents (HAs) through an energy-dependent efflux process. Recently, complete or partial ORFs that encode membrane proteins (MtrC, MtrD, MtrE) forming an efflux pump responsible for removal of HAs from gonococci were identified and appeared to constitute a single transcriptional unit. In this study, the complete nucleotide sequence of the mtrD gene was determined, permitting the characterization of the MtrD protein. The full-length MtrD protein has a predicted molecular mass of nearly 114 kDa, putatively containing a 56 amino acid signal peptide. MtrD displays significant amino acid sequence similarity to a family of cytoplasmic membrane proteins, termed resistance/nodulation/division (RND) proteins, which function as energy-dependent transporters of antibacterial agents and secrete bacterial products to the extracellular fluid. The predicted topology of the MtrD transporter protein revealed 12 potential membrane-spanning domains, which were clustered within the central and C-terminal regions of the primary sequence. Loss of MtrD due to insertional inactivation of the mtrD gene rendered gonococci hypersusceptible to several structurally diverse HAs, including two fatty acids (capric acid and palmitic acid) and a bile salt (cholic acid), but not hydrophilic antibiotics such as ciprofloxacin and streptomycin. Since gonococci often infect mucosal sites rich in toxic fatty acids and bile salts, the expression of the mtr efflux system may promote growth of gonococci under hostile conditions encountered in vivo.
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Affiliation(s)
- Kayla E Hagman
- Dept of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA 30322, USA
- Program in Microbiology and Molecular Genetics of the Graduate Division of Biological and Biomedical Sciences
| | - Claressa E Lucas
- Dept of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA 30322, USA
- Program in Microbiology and Molecular Genetics of the Graduate Division of Biological and Biomedical Sciences
| | - Jacqueline T Balthazar
- Laboratories of Microbial Pathogenesis, VA Medical Research Service, VA Medical Center (Atlanta), Decatur, GA 30033, USA
- Program in Microbiology and Molecular Genetics of the Graduate Division of Biological and Biomedical Sciences
| | - Lori Snyder
- Dept of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA 30322, USA
- Program in Microbiology and Molecular Genetics of the Graduate Division of Biological and Biomedical Sciences
| | - Matthew Nilles
- Department of Microbiology and Immunology, University of Kentucky, Lexington, KY 40536-0084, USA
| | - Ralph C Judd
- Department of Biological Sciences, University of Montana, Missoula, MT 59182-1002, USA
| | - William M Shafer
- Dept of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA 30322, USA
- Program in Microbiology and Molecular Genetics of the Graduate Division of Biological and Biomedical Sciences
- Laboratories of Microbial Pathogenesis, VA Medical Research Service, VA Medical Center (Atlanta), Decatur, GA 30033, USA
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30
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Lucas CE, Balthazar JT, Hagman KE, Shafer WM. The MtrR repressor binds the DNA sequence between the mtrR and mtrC genes of Neisseria gonorrhoeae. J Bacteriol 1997; 179:4123-8. [PMID: 9209024 PMCID: PMC179230 DOI: 10.1128/jb.179.13.4123-4128.1997] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Gonococcal resistance to antimicrobial hydrophobic agents (HAs) is due to energy-dependent removal of HAs from the bacterial cell by the MtrCDE membrane-associated efflux pump. The mtrR (multiple transferrable resistance Regulator) gene encodes a putative transcriptional repressor protein (MtrR) believed to be responsible for regulation of mtrCDE gene expression. Gel mobility shift and DNase I footprint assays that used a maltose-binding protein (MBP)-MtrR fusion protein demonstrated that the MtrR repressor is capable of specifically binding the DNA sequence between the mtrR and mtrC genes. This binding site was localized to a 26-nucleotide stretch that includes the promoter utilized for mtrCDE transcription and, on the complementary strand, a 22-nucleotide stretch that contains the -35 region of the mtrR promoter. A single transition mutation (A-->G) within the MtrR-binding site decreased the affinity of the target DNA for MtrR and enhanced gonococcal resistance to HAs when introduced into HA-susceptible strain FA19 by transformation. Since this mutation enhanced expression of the mtrCDE gene complex but decreased expression of the mtrR gene, the data are consistent with the notion that MtrR acts as a transcriptional repressor of the mtrCDE efflux pump protein genes.
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Affiliation(s)
- C E Lucas
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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Swartley JS, Marfin AA, Edupuganti S, Liu LJ, Cieslak P, Perkins B, Wenger JD, Stephens DS. Capsule switching of Neisseria meningitidis. Proc Natl Acad Sci U S A 1997; 94:271-6. [PMID: 8990198 PMCID: PMC19312 DOI: 10.1073/pnas.94.1.271] [Citation(s) in RCA: 285] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The different sialic acid (serogroups B, C, Y, and W-135) and nonsialic acid (serogroup A) capsular polysaccharides expressed by Neisseria meningitidis are major virulence factors and are used as epidemiologic markers and vaccine targets. However, the identification of meningococcal isolates with similar genetic markers but expressing different capsular polysaccharides suggests that meningococcal clones can switch the type of capsule they express. We identified, except for capsule, isogenic serogroups B [(alpha2-->8)-linked polysialic acid] and C [(alpha2-->9)-linked polysialic acid] meningococcal isolates from an outbreak of meningococcal disease in the U. S. Pacific Northwest. We used these isolates and prototype serogroup A, B, C, Y, and W-135 strains to define the capsular biosynthetic and transport operons of the major meningococcal serogroups and to show that switching from the B to C capsule in the outbreak strain was the result of allelic exchange of the polysialyltransferase. Capsule switching was probably the result of transformation and horizontal DNA exchange in vivo of a serogroup C capsule biosynthetic operon. These findings indicate that closely related virulent meningococcal clones may not be recognized by traditional serogroup-based surveillance and can escape vaccine-induced or natural protective immunity by capsule switching. Capsule switching may be an important virulence mechanism of meningococci and other encapsulated bacterial pathogens. As vaccine development progresses and broader immunization with capsular polysaccharide conjugate vaccines becomes a reality, the ability to switch capsular types may have important implications for the impact of these vaccines.
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Affiliation(s)
- J S Swartley
- Department of Medicine, Emory University School of Medicine, Atlanta, GA 30303, USA
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32
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McGee DJ, Chen GC, Rest RF. Expression of sialyltransferase is not required for interaction of Neisseria gonorrhoeae with human epithelial cells and human neutrophils. Infect Immun 1996; 64:4129-36. [PMID: 8926079 PMCID: PMC174347 DOI: 10.1128/iai.64.10.4129-4136.1996] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Sialyltransferase (Stase) in Neisseria gonorrhoeae organisms (gonococci [GC]) transfers sialic acid (N-acetylneuraminic acid [NANA]) from cytidine 5'-monophospho-N-acetylneuraminic acid (CMP-NANA) mainly to the terminal galactose (Gal) residue in the Gal beta-1,4 N-acetylglucosamine (Gal-GlcNAc)-R lipooligosaccharide (LOS) structure. Sialylated GC resist killing by normal human serum, sometimes show reduced invasion of epithelial cells, and have reduced adhesion to and stimulation of human neutrophils. We questioned whether Stase itself modulates the interactions of GC with human epithelial cells and neutrophils in the absence of exogenous CMP-NANA. To that end, we treated strain F62 with ethyl methanesulfonate and grew approximately 175,000 colonies on CMP-NANA plates, and screened them with monoclonal antibody 1B2-1B7 (MAb 1B2). MAb 1B2 is specific for Gal-GlcNAc and reacts only with asialylated GC. We isolated 13 MAb 1B2-reactive mutants, including five null mutants, that had Stase activities ranging from barely detectable to fivefold less than that of wild-type (WT) F62. The LOS phenotype of Stase null mutants was identical to that of WT F62, yet the mutants could not sialylate their LOS when grown with CMP-NANA. The Stase null phenotype was rescuable to Stase+ by transformation with chromosomal DNA from WT F62. Stase null mutants remained serum sensitive even when grown with CMP-NANA. One Stase null mutant, ST94A, adhered to and invaded the human cervical epithelial cell line ME-180 at levels indistinguishable from that of WT F62 in the absence of CMP-NANA. In human neutrophil studies, ST94A stimulated the oxidative burst in and adhered to human neutrophils at levels similar to those of WT F62. ST94A and WT F62 were also phagocytically killed by neutrophils at similar levels. These results indicate that expression of Stase activity is not required for interaction of GC with human cells.
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Affiliation(s)
- D J McGee
- Department of Microbiology and Immunology, MCP-Hahnemann School of Medicine, Allegheny University of the Health Sciences, Philadelphia, Pennsylvania 19102, USA
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33
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Swartley JS, Ahn JH, Liu LJ, Kahler CM, Stephens DS. Expression of sialic acid and polysialic acid in serogroup B Neisseria meningitidis: divergent transcription of biosynthesis and transport operons through a common promoter region. J Bacteriol 1996; 178:4052-9. [PMID: 8763931 PMCID: PMC178160 DOI: 10.1128/jb.178.14.4052-4059.1996] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
We studied capsule-defective (Cap-) serogroup B meningococcal mutants created through Tn916 or omega-fragment mutagenesis. The Cap- phenotypes were the results of insertions in three of four linked genes (synX, synC, and synD) involved in CMP-N-acetylneuraminic acid and polysialic acid capsule biosynthesis, and in ctrA the first of four linked genes involved in capsule membrane transport. Mutations in the CMP-N-acetylneuraminic acid biosynthesis genes synX and synC caused defects in lipooligosaccharide sialylation but not mutations in the putative (alpha2 -> 8)-linked polysialyltransferase (synD) or in ctrA. Reverse transcriptase PCR studies indicated that the four biosynthesis genes (synX to -D) and the capsule transport genes (ctr to -D) were separately transcribed as operons. The operons were separated by a 134-bp intergenic region. Primer extension of synX and ctrA demonstrated that transcription of the operons was divergently initiated from adjacent start sites present in the intergenic region. Both transcriptional start sites were preceded by a perfect -10 Pribnow promoter binding region. The synX to -D, but not the ctrA to -D, transcriptional start site was preceded by a sequence bearing strong homology to the consensus sigma 70 -35 promoter binding sequence. Both promoters showed transcriptional activity when cloned behind a lacZ reporter gene in Escherichia coli. Our results confirm the intrinsic relationship between polysialic acid capsule biosynthesis and lipooligosaccharide sialylation pathways in group B Neisseria meningitidis. Our study also suggests that the intergenic region separating the synX to -D and ctrA to -D operons is an important control point for the regulation of group B capsule expression through coordinated transcriptional regulation of the synX to -D and drA to -D promoters.
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Affiliation(s)
- J S Swartley
- Department of Medicine, Emory University School of Medicine, Atlanta, Georgia 30303, USA
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34
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Lucas CE, Hagman KE, Levin JC, Stein DC, Shafer WM. Importance of lipooligosaccharide structure in determining gonococcal resistance to hydrophobic antimicrobial agents resulting from the mtr efflux system. Mol Microbiol 1995; 16:1001-9. [PMID: 7476176 DOI: 10.1111/j.1365-2958.1995.tb02325.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Levels of gonococcal resistance to antimicrobial hydrophobic agents (HAs) are controlled by the mtr (multiple transferrable resistance) system, composed of the mtrRCDE genes. The mtrR gene encodes a transcriptional repressor that appears to regulate expression of the upstream and divergent mtrCDE operon. The mtrCDE genes encode membrane proteins analogous to the MexABOprK proteins of Pseudomonas aeruginosa that mediate export of structurally diverse antimicrobial agents. In this study we found that a single base pair deletion in a 13 bp inverted repeat sequence within the mtrR promoter resulted in increased resistance of gonococci to both crystal violet (CV) and erythromycin (ERY) as well as to the more lipophilic non-ionic detergent Triton X-100 (TX-100). However, this cross-resistance was contingent on the production of a full-length lipooligosaccharide (LOS) by the recipient strain used in transformation experiments. Introduction of this mutation (mtrR-171) into three chemically distinct deep-rough LOS mutants by transformation resulted in a fourfold increase in resistance to TX-100 compared with a 160-fold increase in an isogenic strain producing a full-length LOS. However, both wild-type and deep-rough LOS strains exhibited an eightfold increase in resistance to CV and ERY as a result of the mtrR-171 mutation. This suggests that gonococci have different LOS structural requirements for mtr-mediated resistance to HAs that differ in their lipophilic properties. Evidence is presented that gonococci exclude HAs by an energy-dependent efflux process mediated by the mtr system.
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Affiliation(s)
- C E Lucas
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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35
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Cianciotto NP, O'Connell W, Dasch GA, Mallavia LP. Detection of mip-like sequences and Mip-related proteins within the family Rickettsiaceae. Curr Microbiol 1995; 30:149-53. [PMID: 7532505 DOI: 10.1007/bf00296200] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The Mip surface protein, a prokaryotic analog of the FK506-binding proteins, enhances the ability of Legionella pneumophila to infect macrophages and protozoa. Using mip-specific probes and low-stringency Southern hybridizations, we have detected DNA sequences homologous to mip within Coxiella burnetii and Rochalimaea quintana. Using specific anti-Mip antisera and immunoblot analysis, we also detected Mip-related proteins within these bacteria as well as within Rickettsia and Ehrlichia species. These data suggest that Mip-related proteins have broad significance for host-parasite interactions. However, they also indicate that care must be exercised when using mip probes or anti-Mip antibodies for the detection of Legionella organisms in water or clinical samples.
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Affiliation(s)
- N P Cianciotto
- Department of Microbiology-Immunology, Northwestern University, Chicago, Illinois 60611
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36
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Galat A, Metcalfe SM. Peptidylproline cis/trans isomerases. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 1995; 63:67-118. [PMID: 7538221 DOI: 10.1016/0079-6107(94)00009-x] [Citation(s) in RCA: 193] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- A Galat
- Département d'Ingénierie et d'Etudes des Protéines, D.S.V., C.E.A., C.E. Saclay, Gif-sur-Yvette, France
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37
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Herrler M, Bang H, Marahiel MA. Cloning and characterization of ppiB, a Bacillus subtilis gene which encodes a cyclosporin A-sensitive peptidyl-prolyl cis-trans isomerase. Mol Microbiol 1994; 11:1073-83. [PMID: 8022278 DOI: 10.1111/j.1365-2958.1994.tb00384.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Sequencing of N-terminal and internal peptide fragments of the purified 17 kDa Bacillus subtilis peptidyl-prolyl cis-trans isomerase (PPIase) revealed sequence identity to conserved regions of a number of eukaryotic and prokaryotic cyclophilins. Using two oligonucleotide primers corresponding to the N-terminus and a highly conserved internal amino acid sequence, polymerase chain reactions (PCR) with B. subtilis genomic DNA were carried out. The resultant PCR fragment of 335 bp was cloned, sequenced and subsequently used as a probe for screening a lambda Zap II gene library of B. subtilis. Two overlapping positive clones of 5 and 7 kb containing the B. subtilis PPIase gene (ppiB), which is 432 bp in length and encodes a protein of 144 amino acid residues, were identified and two distinct transcriptional initiation sites at the 5' end of ppiB were mapped. The entire region (35 kb) between spoVA and serA was recently sequenced in B. subtilis, and an open reading frame (ORF) that encodes a putative peptidyl-prolyl cis-trans isomerase at about 210 degrees on the B. subtilis genetic map was located. This putative PPIase is identical to PPiB. We have overexpressed the ppiB gene in Escherichia coli, purified the encoded protein to apparent homology and shown that it exhibits PPIase activity. In addition, the recombinant PPiB shows a significant inhibition of PPIase activity by cyclosporin A (CsA) at a level comparable to that observed for the B. subtilis enzyme. Interestingly the B. subtilis PPIase shows about 40% identity to eukaryotic PPIases and less similarity to those of Gram-negative bacteria (27-32% identity). Like other interruption mutants of yeast and Neurospora, which lack a functional cyclophilin gene, a B. subtilis mutant containing ppiB::cat, a cat-interrupted copy of ppiB in the chromosome, is viable.
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Affiliation(s)
- M Herrler
- Philipps-Universität Marburg, Fachbereich Chemie/Biochemie, Germany
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38
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Affiliation(s)
- T F Meyer
- Max-Planck-Institut für Biologie, Abt. Infektionsbiologie, Tübingen, Germany
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