51
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García E, Arrecubieta C, Muñoz R, Mollerach M, López R. A functional analysis of the Streptococcus pneumoniae genes involved in the synthesis of type 1 and type 3 capsular polysaccharides. Microb Drug Resist 2000; 3:73-88. [PMID: 9109098 DOI: 10.1089/mdr.1997.3.73] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Type 3 pneumococci produce a capsule composed of cellobiuronic acid units connected in a beta (1-->3) linkage. Cellobiuronic acid is a disaccharide consisting of D-glucuronic acid (GlcA) beta (1-->4) linked to D-glucose (Glc). The genes implicated in the biosynthesis of the type 3 capsule have been cloned, expressed, and biochemically characterized. The three type 3-specific genes--designated as cap3ABC--are transcribed together. However, the two complete open reading frames located upstream of cap3A are not transcribed and, consequently, are not required for capsule formation. The promoter of the cap3 operon was localized by primer extension analysis. The products of cap3A, cap3B, and cap3C were biochemically characterized as a UDP-Glc dehydrogenase, the type 3 polysaccharide synthase, and a Glc-1-P uridyltransferase, respectively. The Cap3B synthase was expressed in Escherichia coli, and pneumococcal type 3 polysaccharide was synthesized in this heterologous system. When a recombinant plasmid (pLSE3B) containing cap3B was introduced by transformation into encapsulated pneumococci of types 1, 2, 5, or 8, the lincomycin-resistant transformants displayed a binary type of capsule, this is, they showed a type 3 capsule in addition to that of the recipient type. Unencapsulated (S2) laboratory strains of S. pneumoniae also synthesized a type 3 capsule when transformed with pLSE3B. On the other hand, we have cloned and sequenced seven type 1-specific genes (designated as cap1A-G), and their functions have been preliminarily assigned based on sequence similarities.
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Affiliation(s)
- E García
- Centro de Investigaciones Biológicas (CSIC), Madrid, Spain
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52
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Deng L, Kasper DL, Krick TP, Wessels MR. Characterization of the linkage between the type III capsular polysaccharide and the bacterial cell wall of group B Streptococcus. J Biol Chem 2000; 275:7497-504. [PMID: 10713053 DOI: 10.1074/jbc.275.11.7497] [Citation(s) in RCA: 58] [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
The capsular polysaccharide of group B Streptococcus is a key virulence factor and an important target for protective immune responses. Until now, the nature of the attachment between the capsular polysaccharide and the bacterial cell has been poorly defined. We isolated insoluble cell wall fragments from lysates of type III group B Streptococcus and showed that the complexes contained both capsular polysaccharide and group B carbohydrate covalently bound to peptidoglycan. Treatment with the endo-N-acetylmuramidase mutanolysin released soluble complexes of capsular polysaccharide linked to group B carbohydrate by peptidoglycan fragments. Capsular polysaccharide could be enzymatically cleaved from group B carbohydrate by treatment of the soluble complexes with beta-N-acetylglucosaminidase, which catalyzes hydrolysis of the beta-D-GlcNAc(1-->4)beta-D-MurNAc subunit produced by mutanolysin digestion of peptidoglycan. Evidence from gas chromatography/mass spectrometry and (31)P NMR analysis of the separated polysaccharides supports a model of the group B Streptococcus cell surface in which the group B carbohydrate and the capsular polysaccharide are independently linked to the glycan backbone of cell wall peptidoglycan; group B carbohydrate is linked to N-acetylmuramic acid, and capsular polysaccharide is linked via a phosphodiester bond and an oligosaccharide linker to N-acetylglucosamine.
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Affiliation(s)
- L Deng
- Channing Laboratory, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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53
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Charland N, Nizet V, Rubens CE, Kim KS, Lacouture S, Gottschalk M. Streptococcus suis serotype 2 interactions with human brain microvascular endothelial cells. Infect Immun 2000; 68:637-43. [PMID: 10639427 PMCID: PMC97186 DOI: 10.1128/iai.68.2.637-643.2000] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus suis serotype 2 is a worldwide causative agent of many forms of swine infection and is also recognized as a zoonotic agent causing human disease, including meningitis. The pathogenesis of S. suis infections is poorly understood. Bacteria circulate in the bloodstream in the nonimmune host until they come in contact with brain microvascular endothelial cells (BMEC) forming the blood-brain barrier. The bacterial polysaccharide capsule confers antiphagocytic properties. It is known that group B streptococci (GBS) invade and damage BMEC, which may be a primary step in the pathogenesis of neonatal meningitis. Interactions between S. suis and human endothelial cells were studied to determine if they differ from those between GBS and endothelial cells. Invasion assays performed with BMEC and human umbilical vein endothelial cells demonstrated that unlike GBS, S. suis serotype 2 could not invade either type of cell. Adherence assays showed that S. suis adhered only to BMEC, whereas GBS adhered to both types of cell. These interactions were not affected by the presence of a capsule, since acapsular mutants from both bacterial species adhered similarly compared to the wild-type strains. Lactate dehydrogenase release measurements indicated that some S. suis strains were highly cytotoxic for BMEC, even more than GBS, whereas others were not toxic at all. Cell damage was related to suilysin (S. suis hemolysin) production, since only suilysin-producing strains were cytotoxic and cytotoxicity could be inhibited by cholesterol and antisuilysin antibodies. It is possible that hemolysin-positive S. suis strains use adherence and suilysin-induced BMEC injury, as opposed to direct cellular invasion, to proceed from the circulation to the central nervous system.
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Affiliation(s)
- N Charland
- Groupe de Recherche sur les Maladies Infectieuses du Porc, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada J2S 7C6
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54
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Im KI, Park KM, Yong TS, Hong YP, Kim TE. Upregulated expression of the cDNA fragment possibly related to the virulence of Acanthamoeba culbertsoni. THE KOREAN JOURNAL OF PARASITOLOGY 1999; 37:257-63. [PMID: 10634042 PMCID: PMC2733203 DOI: 10.3347/kjp.1999.37.4.257] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Identification of the genes responsible for the recovery of virulence in brain-passaged Acanthamoeba culbertsoni was attempted via mRNA differential display-polymerase chain reaction (mRNA DD-PCR) analysis. In order to identify the regulatory changes in transcription of the virulence related genes by the brain passages, mRNA DD-PCR was performed which enabled the display of differentially transcribed mRNAs after the brain passages. Through mRNA DD-PCR analysis. 96 brain-passaged amoeba specific amplicons were observed and were screened to identify the amplicons that failed to amplify in the non-brain-passaged amoeba mRNAs. Out of the 96 brain-passaged amoeba specific amplicons, 12 turned out to be amplified only from the brain-passaged amoeba mRNAs by DNA slot blot hybridization. The clone, A289C, amplified with an arbitrary primer of UBC #289 and the oligo dT11-C primer, revealed the highest homology (49.8%) to the amino acid sequences of UPD-galactose lipid transferase of Erwinia amylovora, which is known to act as an important virulence factor. The deduced amino acid sequences of an insert DNA in clone A289C were also revealed to be similar to cpsD, which is the essential gene for the expression of type III capsule in group B streptococcus. Upregulated expression of clone A289C was verified by RNA slot blot hybridization. Similar hydrophobicity values were also observed between A289C (at residues 47-66) and the AmsG gene of E. amylovora (at residues 286-305: transmembrane domains). This result suggested that the insert of clone A289C might play the same function as galactosyl transferase controlled by the AmsG gene in E. amylovora.
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Affiliation(s)
- K I Im
- Department of Parasitology, Yonsei University College of Medicine, Seoul, Korea
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55
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Kreikemeyer B, Jerlström PG. An Escherichia coli-Enterococcus faecalis shuttle vector as a tool for the construction of a group B Streptococcus heterologous mutant expressing the beta antigen (Bac) of the C protein complex. FEMS Microbiol Lett 1999; 180:255-62. [PMID: 10556720 DOI: 10.1111/j.1574-6968.1999.tb08804.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Group B streptococci (GBS) represent a very important group of human pathogens. So far little is known about the mechanisms by which these bacteria can cause disease and the bacterial factors involved. One putative virulence factor is the beta antigen of the C protein complex (Bac), which can bind to the Fc region of human IgA. Its binding function might represent an important virulence mechanism. However, the genetic manipulation of this group of bacteria, necessary to prove involvement of bacterial factors in pathogenesis, is still in its infancy. We therefore tested the pAM401 vector system for its suitability in the construction of a heterologous expression mutant using the Bac protein as a model antigen. The bac gene, including its own promoter, was cloned into the Escherichia coli-Enterococcus faecalis shuttle vector pAM401 and was stably maintained extrachromosomally in the bac-deficient GBS strain 335. Expression of Bac was assessed by extracting the protein from transformed 335(pPJTU1) cells, negative controls (335 wild-type, 335(pAM401)) and other Bac-expressing GBS strains (A909, LA239). Blots of the extracted proteins probed with IgA, polyclonal sera and a monoclonal antibody raised against Bac clearly revealed expression of the 130-kDa protein in the transformed GBS 335(pPJTU1) cells. The correct processing and surface anchoring of the expressed Bac was demonstrated by binding of (125)I-labelled IgA to whole cells. Strain 335(pPJTU1) bound 12 times as much IgA compared to the parental strain LA239 and the GBS 335 negative controls, and a total of 25% compared to the high-level-expressing strain A909. Our studies show that the pAM401 shuttle vector can be used for stable heterologous expression of surface proteins in GBS. Our strategy is also of major importance for the complementation of deletion mutants in GBS and other Gram-positive human pathogens to fulfill Koch's postulates. The Bac mutant constructed in this study, 335(pPJTU1), can be used in animal models to assess the importance of Bac in GBS pathogenesis.
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Affiliation(s)
- B Kreikemeyer
- Department of Microbial Pathogenesis and Vaccine Research, GBF-National Research Centre for Biotechnology, Braunschweig, Germany.
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56
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Yamashita Y, Shibata Y, Nakano Y, Tsuda H, Kido N, Ohta M, Koga T. A novel gene required for rhamnose-glucose polysaccharide synthesis in Streptococcus mutans. J Bacteriol 1999; 181:6556-9. [PMID: 10515952 PMCID: PMC103797 DOI: 10.1128/jb.181.20.6556-6559.1999] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Gene rgpG is required for biosynthesis of rhamnose-glucose polysaccharide (RGP) in Streptococcus mutans. Its deduced amino acid sequence had similarity to WecA, which initiates syntheses of enterobacterial common antigen and some O antigens in Escherichia coli. Gene rgpG complemented a wecA mutation of E. coli, suggesting that rgpG may function similarly in RGP synthesis.
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Affiliation(s)
- Y Yamashita
- Department of Preventive Dentistry, Kyushu University Faculty of Dentistry, Fukuoka 812-8582, Japan.
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57
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Yamamoto S, Miyake K, Koike Y, Watanabe M, Machida Y, Ohta M, Iijima S. Molecular characterization of type-specific capsular polysaccharide biosynthesis genes of Streptococcus agalactiae type Ia. J Bacteriol 1999; 181:5176-84. [PMID: 10464185 PMCID: PMC94020 DOI: 10.1128/jb.181.17.5176-5184.1999] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The type-specific capsular polysaccharide (CP) of a group B streptococcus, Streptococcus agalactiae type Ia, is a high-molecular-weight polymer consisting of the pentasaccharide repeating unit 4)-[alpha-D-NeupNAc-(2-->3)-beta-D-Galp-(1-->4)-beta-D-GlcpNAc-(1- ->3 )]-beta-D-Galp-(1-->4)-beta-D-Glcp-(1. Here, cloning, sequencing, and transcription of the type Ia-specific capsular polysaccharide synthesis (cps) genes and functional analysis of these gene products are described. A 26-kb DNA fragment containing 18 complete open reading frames (ORFs) was cloned. These ORFs were designated cpsIaA to cpsIaL, neu (neuraminic acid synthesis gene) A to D, orf1 and ung (uracil DNA glycosylase). The cps gene products of S. agalactiae type Ia were homologous to proteins involved in CP synthesis of S. agalactiae type III and S. pneumoniae serotype 14. Unlike the cps gene cluster of S. pneumoniae serotype 14, transcription of this operon may start from cpsIaA, cpsIaE, and orf1 because putative promoter sequences were found in front of these genes. Northern hybridization, reverse transcription-PCR, and primer extension analyses supported this hypothesis. DNA sequence analysis showed that there were two transcriptional terminators in the 3' end of this operon (downstream of orf1 and ung). The functions of CpsIaE, CpsIaG, CpsIaI, and CpsIaJ were examined by glycosyltransferase assay by using the gene products expressed in Escherichia coli JM109 harboring plasmids containing various S. agalactiae type Ia cps gene fragments. Enzyme assays suggested that the gene products of cpsIaE, cpsIaG, cpsIaI, and cpsIaJ are putative glucosyltransferase, beta-1, 4-galactosyltransferase, beta-1,3-N-acetylglucosaminyltransferase, and beta-1,4-galactosyltransferase, respectively.
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Affiliation(s)
- S Yamamoto
- Department of Biotechnology, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603, Japan
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58
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Butko P, Nicholson-Weller A, Wessels MR. Role of Complement Component C1q in the IgG-Independent Opsonophagocytosis of Group B Streptococcus. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.163.5.2761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
We investigated the role of complement component C1q in the IgG-independent opsonophagocytosis of type III group B Streptococcus (GBS) by peripheral blood leukocytes. We report that C1q binds to type III GBS both in normal human serum deficient in IgG specific for type III capsular polysaccharide and in a low-ionic strength buffer. The dissociation constant Kd ranged from 2.0 to 5.5 nM, and the number of binding sites Bmax ranged from 630 to 1360 molecules of C1q per bacterium (CFU). An acapsular mutant strain of GBS bound C1q even better than the wild type, indicating that the polysaccharide capsule is not the receptor for C1q. In serum, binding of C1q to GBS was associated with activation of the classical complement pathway. However, normal human serum retained significant opsonic activity after complete depletion of C1q, suggesting that the serum contains a molecule that is able to replace C1q in opsonization and/or complement activation. Mannan-binding lectin, known to share some functions with C1q, appeared not to be involved, since its depletion from serum had little effect on opsonic activity. Excess soluble C1q or its collagen-like fragment inhibited phagocytosis mediated by normal human serum, suggesting that C1q may compete with other opsonins for binding to receptor(s) on phagocytes. We conclude that, although C1q binds directly to GBS, C1q binding is neither necessary nor sufficient for IgG-independent opsonophagocytosis. The results raise the possibility that additional unknown serum factor(s) may contribute to opsonization of GBS directly or via a novel mechanism of complement activation.
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Affiliation(s)
| | - Anne Nicholson-Weller
- ‡Division of Infectious Diseases, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115
| | - Michael R. Wessels
- *Channing Laboratory, and
- †Division of Infectious Diseases, Brigham and Women’s Hospital, Boston, MA 02115; and
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59
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Bourgoin F, Pluvinet A, Gintz B, Decaris B, Guédon G. Are horizontal transfers involved in the evolution of the Streptococcus thermophilus exopolysaccharide synthesis loci? Gene 1999; 233:151-61. [PMID: 10375631 DOI: 10.1016/s0378-1119(99)00144-4] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A 32.5kb variable locus of the Streptococcus thermophilus CNRZ368 chromosome, the eps locus, contains 25 ORF and seven insertion sequences (IS). The putative products of 17 ORF are related to proteins involved in the synthesis of polysaccharides in various bacteria. The two distal regions and a small central region of the eps locus are constant and present in all or almost all of the S. thermophilus strains tested. The other regions are variable and present in only some S. thermophilus strains tested, particularly in the closely related strains CNRZ368 and A054. A 13.6kb variable region of the eps locus of S. thermophilus CNRZ368 contains two ORF that are almost identical to epsL and orfY of the eps locus of Lactococcus lactis NIZOB40 and seven IS belonging to four different families, ISS1, IS981, IS1193 and IS1194. Five of these sequences were probably acquired by horizontal transfer from L. lactis (Bourgoin, F., et al., 1996. Gene 178, 15-23). Three probes of this 13.6kb region hybridized with the DNA of several L. lactis strains tested. A specific probe for another sequence within the S. thermophilus eps locus, epsF, hybridized with the DNA of one of the L. lactis strains tested. Sequence comparisons also suggest that five ORF of the eps locus have a mosaic structure and probably result from recombinations between sequences that are 10 to 50% divergent. The chimeric structure of the eps locus suggests a very complex evolution. This evolution probably involves both the acquisition of the 13.6kb region from L. lactis by horizontal transfer and exchanges within the S. thermophilus species.
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Affiliation(s)
- F Bourgoin
- Laboratoire de Génétique et Microbiologie, UA INRA 952, Université Henri Poincaré Nancy I, Faculté des Sciences, BP 239, 54506, Vandoeuvre-lès-Nancy, France.
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60
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Spellerberg B, Pohl B, Haase G, Martin S, Weber-Heynemann J, Lütticken R. Identification of genetic determinants for the hemolytic activity of Streptococcus agalactiae by ISS1 transposition. J Bacteriol 1999; 181:3212-9. [PMID: 10322024 PMCID: PMC93778 DOI: 10.1128/jb.181.10.3212-3219.1999] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus agalactiae is a poorly transformable bacterium and studies of molecular mechanisms are difficult due to the limitations of genetic tools. Employing the novel pGh9:ISS1 transposition vector we generated plasmid-based mutant libraries of S. agalactiae strains O90R and AC475 by random chromosomal integration. A screen for mutants with a nonhemolytic phenotype on sheep blood agar led to the identification of a genetic locus harboring several genes that are essential for the hemolytic function and pigment production of S. agalactiae. Nucleotide sequence analysis of nonhemolytic mutants revealed that four mutants had distinct insertion sites in a single genetic locus of 7 kb that was subsequently designated cyl. Eight different open reading frames were identified: cylX, cylD, cylG, acpC, cylZ, cylA, cylB, and cylE, coding for predicted proteins with molecular masses of 11, 33, 26, 11, 15, 35, 32, and 78 kDa, respectively. The deduced amino acid sequence of the protein encoded by cylA harbors a conserved ATP-binding cassette (ABC) motif, and the predicted proteins encoded by cylA and cylB have significant similarities to the nucleotide binding and transmembrane proteins of typical ABC transporter systems. Transcription analysis by reverse transcription-PCR suggests that cylX to cylE are part of an operon. The requirement of acpC and cylZABE for hemolysin production of S. agalactiae was confirmed either by targeted mutagenesis with the vector pGh5, complementation studies with pAT28, or analysis of insertion elements in naturally occurring nonhemolytic mutants.
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Affiliation(s)
- B Spellerberg
- Institute of Medical Microbiology, University Hospital Aachen, D-52057 Aachen, Germany
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61
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van Kranenburg R, van Swam II, Marugg JD, Kleerebezem M, de Vos WM. Exopolysaccharide biosynthesis in Lactococcus lactis NIZO B40: functional analysis of the glycosyltransferase genes involved in synthesis of the polysaccharide backbone. J Bacteriol 1999; 181:338-40. [PMID: 9864348 PMCID: PMC103567 DOI: 10.1128/jb.181.1.338-340.1999] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We used homologous and heterologous expression of the glycosyltransferase genes of the Lactococcus lactis NIZO B40 eps gene cluster to determine the activity and substrate specificities of the encoded enzymes and established the order of assembly of the trisaccharide backbone of the exopolysaccharide repeating unit. EpsD links glucose-1-phosphate from UDP-glucose to a lipid carrier, EpsE and EpsF link glucose from UDP-glucose to lipid-linked glucose, and EpsG links galactose from UDP-galactose to lipid-linked cellobiose. Furthermore, EpsJ appeared to be involved in EPS biosynthesis as a galactosyl phosphotransferase or an enzyme which releases the backbone oligosaccharide from the lipid carrier.
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Affiliation(s)
- R van Kranenburg
- Microbial Ingredients Section, NIZO Food Research, 6710 BA Ede, The
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62
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Winram SB, Jonas M, Chi E, Rubens CE. Characterization of group B streptococcal invasion of human chorion and amnion epithelial cells In vitro. Infect Immun 1998; 66:4932-41. [PMID: 9746599 PMCID: PMC108610 DOI: 10.1128/iai.66.10.4932-4941.1998] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Group B streptococci (GBS) have been cultured from the chorioamnionic membrane of pregnant women, usually in association with chorioamnionitis and premature labor (K. A. Boggess, D. H. Watts, S. L. Hillier, M. A. Krohn, T. J. Benedetti, and D. A. Eschenbach, Obstet. Gynecol. 87:779-784, 1996). Colonization and infection of placental membranes can be a prelude to neonatal GBS infections even in the presence of intact membranes (R. L. Naeye and E. C. Peters, Pediatrics 61:171-177, 1978), suggesting that GBS cause chorioamnionitis or establish amniotic fluid infections by partial or complete penetration of the placental membranes. We have isolated and grown cultures of primary chorion and amnion cells from human cesarean-section placentas. This has provided a biologically relevant model for investigating GBS adherence to and invasion of the two epithelial barriers of the placental membrane. GBS adhered to chorion cell monolayers to a high degree. Pretreatment of GBS with trypsin reduced adherence up to 10-fold, which suggested that the bacterial ligand(s) was a protein. GBS invaded chorion cells at a high rate in vitro, and invasion was dependent on cellular actin polymerization. GBS could be seen within intracellular vacuoles of chorion cells by transmission electron microscopy. We also demonstrated that GBS were capable of transcytosing through intact chorion cell monolayers without disruption of intracellular junctions. GBS also adhered to amnion cells; in contrast, however, these bacteria failed to invade amnion cells under a variety of assay conditions. GBS interactions with the chorion epithelial cell layer shown here correlate well with epidemiological and pathological studies of GBS chorioamnionitis. Our data also suggest that the amnion cell layer may provide an effective barrier against infection of the amniotic fluid.
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Affiliation(s)
- S B Winram
- Department of Pediatrics, Division of Infectious Diseases, Children's Hospital and Regional Medical Center, University of Washington, Seattle, Washington 98105, USA
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63
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Segura MA, Cléroux P, Gottschalk M. Streptococcus suis and group B Streptococcus differ in their interactions with murine macrophages. FEMS IMMUNOLOGY AND MEDICAL MICROBIOLOGY 1998; 21:189-95. [PMID: 9718208 DOI: 10.1111/j.1574-695x.1998.tb01165.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Streptococcus suis type 2 and group B Streptococcus type III (GBS) are important encapsulated bacterial species causing meningitis. In the present study we compared quantitatively the uptake and intracellular survival of S. suis type 2 and GBS type III with murine macrophages in non-opsonic conditions. The role of the capsule of both pathogens was also studied using previously obtained unencapsulated isogenic mutants. Encapsulated S. suis wild-type strain was practically not phagocytosed, while the unencapsulated mutant was easily ingested by macrophages. On the other hand, the well encapsulated GBS strain and its unencapsulated mutant were both phagocytosed in large numbers. Even if S. suis unencapsulated mutant showed a higher uptake rate than the parental strain, this value was always markedly lower than the numbers of ingested GBS strains. In addition, the intracellular survival of encapsulated and unencapsulated GBS strains was significantly higher than that of S. suis strains. These results suggest that interactions between GBS type III and S. suis type 2 with murine macrophages as well as the role of the capsule as an antiphagocytic factor are different for the two bacterial pathogens.
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Affiliation(s)
- M A Segura
- Groupe de Recherche sur les Maladies Infectieuses du Porc, Faculté de Médecine Vétérinaire, Université de Montréal, Qué, Canada
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64
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Koskiniemi S, Sellin M, Norgren M. Identification of two genes, cpsX and cpsY, with putative regulatory function on capsule expression in group B streptococci. FEMS IMMUNOLOGY AND MEDICAL MICROBIOLOGY 1998; 21:159-68. [PMID: 9685006 DOI: 10.1111/j.1574-695x.1998.tb01162.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Two divergently transcribed open reading frames: cpsX and cpsY separated by a common regulatory region was identified upstream of the cpsA-D genes involved in polysaccharide capsule biosynthesis in group B streptococci (GBS). We suggest that these genes are involved in the regulation of capsule expression in GBS, since the CpsX protein shares sequence similarities with LytR of Bacillus subtilis, an attenuator of transcription while CpsY has similarity to a wide variety of members of the LysR family of transcriptional regulators. No deletions, insertions, DNA rearrangements, or apparent differences were discovered in the postulated regulatory genes when the gene region was compared in GBS with different capsule phenotypes. Thus, other yet unidentified gene loci may control capsule phase variation in GBS.
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Affiliation(s)
- S Koskiniemi
- Department of Clinical Bacteriology, Umeå University, Sweden
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65
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Charland N, Harel J, Kobisch M, Lacasse S, Gottschalk M. Streptococcus suis serotype 2 mutants deficient in capsular expression. MICROBIOLOGY (READING, ENGLAND) 1998; 144 ( Pt 2):325-332. [PMID: 9493370 DOI: 10.1099/00221287-144-2-325] [Citation(s) in RCA: 121] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Streptococcus suis serotype 2 is responsible for a wide variety of porcine infections. In addition, it is considered a zoonotic agent. Knowledge about the virulence factors for this bacterium is limited but its polysaccharide capsule is thought to be one of the most important. Transposon mutagenesis with the self-conjugative transposon Tn916 was used to obtain acapsular mutants from the virulent S. suis type 2 reference strain S735. Clones were screened by colony-dot ELISA with a monoclonal antibody specific for a type 2 capsular epitope and clones that failed to react with the antibody were characterized. Two mutants, 2A and 79, having one and two Tn916 insertions respectively, were chosen for further characterization. Absence of capsule was confirmed by coagglutination, capillary precipitation and capsular reaction tests and by transmission electron microscopy. Absence of capsular polysaccharides correlated with increased hydrophobicity and phagocytosis by both murine macrophages and porcine monocytes compared to the wild-type strain. Furthermore, both mutants were shown to be avirulent in murine and pig models of infection. Finally, mutant 2A was readily eliminated from circulation in mice compared to the wild-type strain, which persisted more than 48 h in blood. Thus, isogenic mutants defective in capsule production demonstrate the importance of capsular polysaccharides as a virulence factor for S. suis type 2.
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Affiliation(s)
- Nathalie Charland
- Groupe de Recherche sur les Maladies Infectieuses du Porc, Faculté de médecine vétérinaire, Université de Montréal, CP 5000, St-Hyacinthe, Québec, Canada J2S 7C6
| | - Josée Harel
- Groupe de Recherche sur les Maladies Infectieuses du Porc, Faculté de médecine vétérinaire, Université de Montréal, CP 5000, St-Hyacinthe, Québec, Canada J2S 7C6
| | - Marylène Kobisch
- Centre National d'Études Vétérinaires et alimentaires, Unité Mycoplasmologie Bactériologie, BP 53, Zoopôle, 22440 Ploufragan, France
| | - Serge Lacasse
- Groupe de Recherche sur les Maladies Infectieuses du Porc, Faculté de médecine vétérinaire, Université de Montréal, CP 5000, St-Hyacinthe, Québec, Canada J2S 7C6
| | - Marcelo Gottschalk
- Groupe de Recherche sur les Maladies Infectieuses du Porc, Faculté de médecine vétérinaire, Université de Montréal, CP 5000, St-Hyacinthe, Québec, Canada J2S 7C6
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66
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Abstract
For the past two decades, group B streptococcus (GBS) has been the pathogen most frequently isolated from neonates with invasive bacterial disease. This is a review of the relevant aspects of microbiology, epidemiology, and clinical manifestations and a summary of the major studies of prevention strategies that led to the development of the 1996 consensus guidelines for prevention of perinatal GBS disease. There is now sufficient experience to know that > or = 80% of cases of early onset GBS disease can be prevented when a protocol for intrapartum chemoprophylaxis with either penicillin or ampicillin is implemented consistently within a delivery population. Present controversies revolve around the choice between a universal screening-based strategy versus a risk factor-based strategy, optimal management of the neonate born to a mother who received intrapartum antimicrobial prophylaxis, and effective methods to ensure implementation. The present guidelines will likely be refined as additional experience is gained.
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Affiliation(s)
- J D Siegel
- Department of Pediatrics, University of Texas, Southwestern Medical Center at Dallas 75235-9063, USA
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67
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Grangeasse C, Doublet P, Vaganay E, Vincent C, Deléage G, Duclos B, Cozzone AJ. Characterization of a bacterial gene encoding an autophosphorylating protein tyrosine kinase. Gene X 1997; 204:259-65. [PMID: 9434192 DOI: 10.1016/s0378-1119(97)00554-4] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Acinetobacter johnsonii harbors a protein tyrosine kinase activity that is able to catalyze autophosphorylation, like a number of eukaryotic tyrosine kinases. A biochemical and genetic analysis of this enzyme was performed. Maximum phosphorylation in vitro was obtained by incubating the kinase for 2 min at pH 7.0 in the presence of 5 mM magnesium chloride. In contrast to eukaryotic enzymes, no inhibitory effect of genistein and no phosphorylation of synthetic substrates such as poly (Glu80 Tyr20) or angiotensin II were observed. The analysis of the bacterial kinase by two-dimensional gel electrophoresis revealed the presence of at least five isoforms, all phosphorylated exclusively at tyrosine, which supports the concept that autophosphorylation occurs at multiple sites within the protein. The cloning and nucleotide sequencing of the gene encoding this kinase were achieved, which represents the first molecular characterization of a gene of this type in bacteria. An open reading frame of 2199 nucleotides encoding a protein of 82,373 Da was detected. The analysis of the deduced amino acid sequence suggested a possible involvement of the enzyme in cell recognition and bacterial pathogenicity. In addition, the cloning and sequencing of the region immediately upstream of the gene encoding the kinase revealed a novel open reading frame of 426 nucleotides encoding a phosphotyrosine protein phosphatase of 16,217 Da, which indicates that autophosphorylation on tyrosine is a physiologically reversible reaction.
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Affiliation(s)
- C Grangeasse
- Institut de Biologie et Chimie des Protéines, Centre National de la Recherche Scientifique, Lyon, France
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68
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Ferrieri P, Cho DS, Livdahl C, Rubens CE, Flores AE. DNA restriction profiles of nontypable group B streptococcal clinical isolates. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1997; 418:343-6. [PMID: 9331666 DOI: 10.1007/978-1-4899-1825-3_82] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- P Ferrieri
- Department of Laboratory Medicine, University of Minnesota Medical School, Minneapolis, USA
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69
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Deng L, Wessels MR. Glycolipid intermediates in biosynthesis of group B streptococcal capsular polysaccharide. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1997; 418:623-5. [PMID: 9331729 DOI: 10.1007/978-1-4899-1825-3_145] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- L Deng
- Channing Laboratory, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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70
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Kolkman MA, van der Zeijst BA, Nuijten PJ. Functional analysis of glycosyltransferases encoded by the capsular polysaccharide biosynthesis locus of Streptococcus pneumoniae serotype 14. J Biol Chem 1997; 272:19502-8. [PMID: 9235953 DOI: 10.1074/jbc.272.31.19502] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Bacteria belonging to the species Streptococcus pneumoniae vary in their capsule. Presently, 90 capsular serotypes are known, all possessing their own specific polysaccharide structure. Little is known about the biosynthesis of these capsular polysaccharides. The cps locus of S. pneumoniae serotype 14 was cloned. So far, 7 open reading frames have been sequenced, cps14B to cps14H. The gene products are similar to proteins involved in bacterial polysaccharide biosynthesis, both of Gram-negative and -positive micro-organisms. Gene-specific mutants were created for cps14D to cps14H by insertional mutagenesis. All mutants no longer agglutinated with a monoclonal antibody against type 14 capsule polysaccharides. The biosynthetic function of cps14E and cps14G was determined by analysis of the intermediates in the synthesis of the oligosaccharide subunit, formed in membrane preparations of the wild-type and mutant strains and in membrane preparations of Escherichia coli expressing the pneumococcal glycosyltransferases. The enzyme encoded by cps14E is a glucosyl-1-phosphate transferase that links glucose to a lipid carrier, the first step in the biosynthesis of the type 14 repeating unit. The gene product of cps14G encodes a beta-1,4-galactosyltransferase, the enzyme responsible for the second step in the subunit synthesis, the transfer of galactose to lipid-linked glucose.
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Affiliation(s)
- M A Kolkman
- Department of Bacteriology, Institute of Infectious Diseases and Immunology, School of Veterinary Medicine, University of Utrecht, 3508 TD Utrecht, The Netherlands
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71
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Sau S, Bhasin N, Wann ER, Lee JC, Foster TJ, Lee CY. The Staphylococcus aureus allelic genetic loci for serotype 5 and 8 capsule expression contain the type-specific genes flanked by common genes. MICROBIOLOGY (READING, ENGLAND) 1997; 143 ( Pt 7):2395-2405. [PMID: 9245821 DOI: 10.1099/00221287-143-7-2395] [Citation(s) in RCA: 126] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The nucleotide sequences of two gene clusters, cap5 and cap8, involved in the synthesis of Staphylococcus aureus type 5 and type 8 capsular polysaccharides (CPs), respectively were determined. Each gene cluster contained 16 ORFs, which were named cap5A through cap5P for type 5 CP and cap8A through cap8P for type 8 CP. The cap5 and cap8 loci were allelic and were mapped to the SmaI-G fragment in the standard SmaI map of Staph. aureus strain NCTC 8325. The predicted gene products of cap5A through cap5G and cap5L through cap5P are essentially identical to those of cap8A through cap8G and cap8L through cap8P, respectively, with very few amino acid substitutions. Four ORFs located in the central region of each locus are type-specific. A comparison of the predicted amino acid sequences of cap5 and cap8 with sequences found in the databases allowed tentative assignment of functions to 15 of the 16 ORFs. The majority of the capsule genes are likely to be involved in amino sugar synthesis; the remainder are likely to be involved in sugar transfer, capsule chain-length regulation, polymerization and transport.
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Affiliation(s)
- Subrata Sau
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas 66160, USA
| | - Navneet Bhasin
- Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Elisabeth R Wann
- Microbiology Department, Moyne Institute, Trinity College, Dublin 2, Ireland
| | - Jean C Lee
- Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Timothy J Foster
- Microbiology Department, Moyne Institute, Trinity College, Dublin 2, Ireland
| | - Chia Y Lee
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas 66160, USA
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72
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Abstract
The polysaccharide capsule of Streptococcus pneumoniae is the main virulence factor of this microorganism. Although the study of the genes responsible for the synthesis of the pneumococcal capsule enabled genetic and molecular analysis, the precise structure, organization, and functioning of these genes have only been investigated very recently. The genes implicated in the production of the type 3 capsule have been sequenced, expressed and their corresponding products biochemically characterized. In addition, partial information on the genes responsible for the biosynthesis of the capsules of pneumococcal types 1, 14 or 19 F is currently available.
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Affiliation(s)
- E García
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
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73
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van Workum WA, Canter Cremers HC, Wijfjes AH, van der Kolk C, Wijffelman CA, Kijne JW. Cloning and characterization of four genes of Rhizobium leguminosarum bv. trifolii involved in exopolysaccharide production and nodulation. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 1997; 10:290-301. [PMID: 9057334 DOI: 10.1094/mpmi.1997.10.2.290] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Four different genes of Rhizobium leguminosarum bv. trifolii strain RBL5599 involved in exopolysaccharide (EPS) production were identified by complementation of Tn5-induced EPS-deficient mutants (Exo mutants) with a cosmid bank. On one cosmid pssA was located, which was found to be almost identical to the pss4 gene from R. leguminosarum bv. viciae VF39 and highly homologous to a family of glycosyl transferases. Two pssA mutants, exo2 and exo4, were characterized and found to produce 19 and 1% of the wild-type amount of EPS, respectively. The three other genes were found to be closely linked on a different complementing cosmid. pssC revealed similarity to exoM and exoW of R. meliloti, both encoding glucosyl transferases involved in the synthesis of succinoglycan. A mutation in this gene (mutant exo50) did reduce EPS synthesis to 27% of the wild-type amount. We found an operon closely linked to pssC, consisting of two overlapping genes, pssD and pssE, that is essential for EPS production. Homology of pssD and pssE was found with cps14F and cps14G of Streptococcus pneumoniae, respectively: two genes responsible for the second step in capsule polysaccharide synthesis. Furthermore, pssD and pssE were homologous to the 5' and 3' parts, respectively, of spsK of Sphingomonas S88, which encodes a putative glycosyl transferase. Structural analysis of EPS produced by Exo mutants exo2, exo4, and exo50 showed it to be identical to that of the parental strain RBL5599, with the exception of acetyl groups esterified to one of the glucose residues being absent.
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Affiliation(s)
- W A van Workum
- Institute of Molecular Plant Sciences, Leiden University, The Netherlands.
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74
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Deng L, Anderson JS. Biosynthesis of teichuronic acid in the bacterial cell wall. Purification and characterization of the glucosyltransferase of Micrococcus luteus. J Biol Chem 1997; 272:479-85. [PMID: 8995286 DOI: 10.1074/jbc.272.1.479] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
This report describes what is, to our knowledge, the first purification to near homogeneity of an enzyme involved in the biosynthesis of the teichuronic acid of Micrococcus luteus cell walls. The glucosyltransferase of M. luteus, which participates in the biosynthesis of teichuronic acid, was solubilized from cytoplasmic membrane fragments by extraction with buffer solutions containing the detergents Thesit (dodecyl alcohol polyoxyethylene ether; 1 mg/ml) and 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (0.5 mg/ml). The detergent-solubilized enzyme was purified 150-fold, with a recovery of 13% by adsorbent column chromatography, ion-exchange chromatography, gel filtration, and preparative nondenaturing gradient polyacrylamide gel electrophoresis. On the basis of its mobility on native gradient gel, the glucosyltransferase was estimated to have a molecular mass of 440 kDa. The purified native enzyme was a multisubunit protein consisting of subunits of two sizes; their molecular masses were determined to be 52.5 and 54 kDa, respectively, by observation of the mobility of the protein bands in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The isoelectric point of the enzyme was approximately 5.
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Affiliation(s)
- L Deng
- Department of Biochemistry, College of Biological Sciences, University of Minnesota, St. Paul 55108, USA
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75
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Griffin AM, Morris VJ, Gasson MJ. The cpsABCDE genes involved in polysaccharide production in Streptococcus salivarius ssp. thermophilus strain NCBF 2393. Gene X 1996; 183:23-7. [PMID: 8996082 DOI: 10.1016/s0378-1119(96)00405-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
A 4074-bp EcoRI fragment of Streptococcus salivarius ssp. thermophilus (S. thermophilus) chromosomal DNA containing genes involved in exocellular polysaccharide (EPS) was identified and cloned. The nucleotide sequence of this fragment was determined and found to contain one partial and four complete open reading frames. These were designated cpsA, cpsB, cpsC, cpsD and cpsE and encoded proteins of > 130, 243, 230, 246 and 455 amino acids, respectively, that showed homology with the genes of the cps cluster, involved in polysaccharide biosynthesis, in Streptococcus pneumoniae Type 19F. The cpsA gene is predicted to encode a transcriptional regulator, while cpsC and cpsD are predicted to encode proteins involved in polysaccharide polymerization and export. The cpsE gene is likely to encode the phosphate-prenyl glycosyl-1-phosphate transferase catalyzing the first step in polysaccharide biosynthesis in S. thermophilus. Southern blot analysis revealed that cpsE is found only in polysaccharide producing strains of S. thermophilus.
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Affiliation(s)
- A M Griffin
- Genetics and Microbiology Department, Institute of Food Research, Norwich Laboratory, Colney, UK.
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76
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Petroni EA, Ielpi L. Isolation and nucleotide sequence of the GDP-mannose:cellobiosyl-diphosphopolyprenol alpha-mannosyltransferase gene from Acetobacter xylinum. J Bacteriol 1996; 178:4814-21. [PMID: 8759843 PMCID: PMC178262 DOI: 10.1128/jb.178.16.4814-4821.1996] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
A genetic locus from Acetobacter xylinum involved in acetan polysaccharide synthesis has been characterized. The chromosomal region was identified by screening a genomic library of A. xylinum in a Xanthomonas campestris mutant defective in xanthan polysaccharide synthesis. The A. xylinum cosmid clone can functionally complement a xanthan-negative mutant. The polymer produced by the recombinant strain was found to be indistinguishable from xanthan. Insertion mutagenesis and subcloning of the cosmid clone combined with complementation studies allowed the identification of a 2.3-kb fragment of A. xylinum chromosomal DNA. The nucleotide sequence of this fragment was analyzed and found to contain an open reading frame (aceA) of 1,182 bp encoding a protein of 43.2 kDa. Results from biochemical and genetic analyses strongly suggest that the aceA gene encodes the GDP-mannose:cellobiosyl-diphosphopolyprenol alpha-mannosyltransferase enzyme, which is responsible for the transfer of an alpha-mannosyl residue from GDP-Man to cellobiosyl-diphosphopolyprenol. A search for similarities with other known mannosyltransferases revealed that all bacterial alpha-mannosyltransferases have a short COOH-terminal amino acid sequence in common.
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Affiliation(s)
- E A Petroni
- Instituto de Investigaciones Bioquímicas Fundación Campomar, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina
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77
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Kolkman MA, Morrison DA, Van Der Zeijst BA, Nuijten PJ. The capsule polysaccharide synthesis locus of streptococcus pneumoniae serotype 14: Identification of the glycosyl transferase gene cps14E. J Bacteriol 1996; 178:3736-41. [PMID: 8682774 PMCID: PMC232630 DOI: 10.1128/jb.178.13.3736-3741.1996] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
To identify a chromosomal region of Streptococcus pneumoniae serotype 14 involved in capsule polysaccharide synthesis, two strategies were used: (i) Tn916 mutagenesis, followed by the characterization of four unencapsulated mutants, and (ii) cross-hybridization with a capsule polysaccharide synthesis gene (cps) probe from S. agalactiae, which has a structurally similar capsule. The two approaches detected the same chromosomal region consisting of two adjacent EcoRI fragments. One of these EcoRI fragments was cloned and hybridized with a cosmid library. This resulted in clone cMKO2. A similar cosmid clone was obtained from an unencapsulated Tn916 mutant, Spnl4.H. Sequence analysis of the two cosmid clones revealed that in the Tn916 mutant, a gene, cps14E, which is homologous to other bacterial genes encoding glycosyl transferases, had been inactivated. An open reading frame immediately downstream of cps14E, designated cps14F, shows no significant homology with any known genes or proteins. A functional assay showed that cps14E encodes a glycosyl transferase and that a gene-specific knockout mutant lacks this enzyme activity, whereas inactivation of cps14F does not have this effect.
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Affiliation(s)
- M A Kolkman
- Department of Bacteriology, Institute of Infectious Diseases and Immunology, School of Veterinary Medicine, University of Utrecht, The Netherlands
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78
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Yamazaki M, Thorne L, Mikolajczak M, Armentrout RW, Pollock TJ. Linkage of genes essential for synthesis of a polysaccharide capsule in Sphingomonas strain S88. J Bacteriol 1996; 178:2676-87. [PMID: 8626338 PMCID: PMC177995 DOI: 10.1128/jb.178.9.2676-2687.1996] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Several structurally related capsular polysaccharides that are secreted by members of the genus Sphingomonas are being developed as aqueous rheological control agents for diverse industrial and food applications. They include gellan (S-60), welan (S-130), rhamsan (S-194), S-657, S-88, S-198, S-7, and NW-11. We refer to these polysaccharides as sphingans, after the genus name. This paper characterizes the first gene cluster isolated from a Sphingomonas species (S88) that is required for capsule synthesis. Overlapping DNA segments which spanned about 50 kbp of S88 DNA restored the synthesis of sphingan S-88 in capsule-negative mutants. The mutations were mapped into functional complementation groups, and the contiguous nucleotide sequence for the 29-kbp cluster was determined. The genetic complementation map and the DNA sequences were interpreted as an extended multicistronic locus containing genes essential for the assembly and secretion of polysaccharide S-88. Many of the deduced amino acid sequences were similar to gene products from other polysaccharide-secreting bacteria such as Rhizobium meliloti (succinoglycan), Xanthomonas campestris (xanthan gum), and Salmonella enterica (O antigen). The S88 locus contained a four-gene operon for the biosynthesis of dTDP-L-rhamnose, an essential precursor for the sphingans. Unexpectedly, there were also two genes for secretion of a lytic or toxin-like protein nested within the polysaccharide cluster. The conservation and linkage of genes that code for a defensive capsule and genes for secretion of an offensive lysin or toxin suggest a heretofore unknown pathogenic life history for Sphingomonas strain S88.
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Affiliation(s)
- M Yamazaki
- Shin-Etsu Bio, Inc., San Diego, California 92121, USA
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79
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Wang L, Liu D, Reeves PR. C-terminal half of Salmonella enterica WbaP (RfbP) is the galactosyl-1-phosphate transferase domain catalyzing the first step of O-antigen synthesis. J Bacteriol 1996; 178:2598-604. [PMID: 8626328 PMCID: PMC177985 DOI: 10.1128/jb.178.9.2598-2604.1996] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
We previously showed that the product of the wbaP gene of Salmonella enterica serovar Typhimurium has two functions: it is involved in the first step of O-antigen synthesis (the galactosyltransferase [GT] function) and in a later step (the T function), first thought to be the flipping of the O-antigen subunit on undecaprenyl pyrophosphate from the cytoplasmic face to the periplasmic face of the cytoplasmic membrane. We now locate two wbaP(T) mutations within the first half of the wbaP gene by sequencing. Both mutants retain GT activity, although one was a frameshift mutation resulting in a stop codon 10 codons after the frameshift to give an open reading frame containing only 138 of the 476 codons in WbaP. We also show that there is a secondary translation starting within the wbaP gene resulting in the synthesis of a polypeptide with GT activity. These results indicate that the N- and C-terminal halves of WbaP are the T and GT functional domains, respectively. We now propose that the T block operates prior to the flippase function, probably at the release of undecaprenyl pyrophosphate-linked galactose from WbaP.
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Affiliation(s)
- L Wang
- Department of Microbiology, The University of Sydney, New South Wales, Australia
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80
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Paoletti LC, Ross RA, Johnson KD. Cell growth rate regulates expression of group B Streptococcus type III capsular polysaccharide. Infect Immun 1996; 64:1220-6. [PMID: 8606082 PMCID: PMC173907 DOI: 10.1128/iai.64.4.1220-1226.1996] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The capsular polysaccharide (CPS) of group B streptococci (GBS) is an important virulence factor that also serves to protect cells from nonspecific host defense mechanisms. Expression of CPS by GBS, as with other encapsulated bacterial pathogens, is not constitutive but varies during growth in vitro and in primary cultures isolated from different sites of infection. Despite this understanding, little is known about regulation of this surface-expressed carbohydrate antigen in GBS. Here we report that expression of type III CPS by GBS strain M781 grown in continuous culture with a modified chemically defined medium is regulated by growth rate. Cells in steady state at mass doubling times (tds) of 0.8, 1.4, and 1.6 h expressed an average of sixfold more cell-associated CPS than did cells held at tds of 2.3 and 11 h. Strain M781 grown at a td of 1.4 h repeatedly produced more type III CPS than those held at a td of 11.0 h, even when limited for glucose, pyridoxamine, or thiamine. In our studies, > or = 93% of the total CPS expressed by strain M781 was cell associated. Strain M781 grown at a td of 11.0 h (i.e., lowered CPS expression) was susceptible to in vitro complement-mediated opsonophagocytosis and killing by human peripheral blood leukocytes, whereas cells grown at a td of 1.4 h (i.e., higher CPS expression) were not killed unless type III CPS-specific antibody was present. Factors that allow GBS to asymptomatically colonize women yet cause invasive infection to both mother and infant are poorly understood. Our results shed new light on parameters that regulate the pathogenic potential of GBS and may also serve as a way to discern more fully the genetics and biochemistry of GBS capsule synthesis.
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Affiliation(s)
- L C Paoletti
- Channing Laboratory, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, 02115, USA
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81
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Griffin AM, Morris VJ, Gasson MJ. Identification, cloning and sequencing the aceA gene involved in acetan biosynthesis in Acetobacter xylinum. FEMS Microbiol Lett 1996; 137:115-21. [PMID: 8935665 DOI: 10.1111/j.1574-6968.1996.tb08092.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The aceA gene from Acetobacter xylinum was identified and cloned from a genomic DNA library. The complete DNA sequence was determined and computer analysis of the translated gene sequence revealed homology with the deduced amino acid sequence of gumD from Xanthomonas campestris. Therefore aceA is likely to encode the phosphate-prenyl glucose l-phosphate transferase catalyzing the first step in acetan biosynthesis in A. xylinum.
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Affiliation(s)
- A M Griffin
- Institute of Food Research, Norwich Laboratory, Colney, UK. annette.griffin/b
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82
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Stingele F, Neeser JR, Mollet B. Identification and characterization of the eps (Exopolysaccharide) gene cluster from Streptococcus thermophilus Sfi6. J Bacteriol 1996; 178:1680-90. [PMID: 8626297 PMCID: PMC177854 DOI: 10.1128/jb.178.6.1680-1690.1996] [Citation(s) in RCA: 212] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
We report the identification and characterization of the eps gene cluster of Streptococcus thermophilus Sfi6 required for exopolysaccharide (EPS) synthesis. This report is the first genetic work concerning EPS production in a food microorganism. The EPS secreted by this strain consists of the following tetrasaccharide repeating unit:-->3)-beta-D-Galp-(1-->3)-[alpha-D-Galp-(1-->6)]-beta-D- D-Galp-(1-->3)-alpha-D-Galp-D-GalpNAc-(1-->. The genetic locus The genetic locus was identified by Tn916 mutagenesis in combination with a plate assay to identify Eps mutants. Sequence analysis of the gene region, which was obtained from subclones of a genomic library of Sfi6, revealed a 15.25-kb region encoding 15 open reading frames. EPS expression in the non-EPS-producing heterologous host, Lactococcus lactis MG1363, showed that within the 15.25-kb region, a region with a size of 14.52 kb encoding the 13 genes epsA to epsM was capable of directing EPS synthesis and secretion in this host. Homology searches of the predicted proteins in the Swiss-Prot database revealed high homology (40 to 68% identity) for epsA, B, C, D, and E and the genes involved in capsule synthesis in Streptococcus pneumoniae and Streptococcus agalactiae. Moderate to low homology (37 to 18% identity) was detected for epsB, D, F, and H and the genes involved in capsule synthesis in Staphylococcus aureus for epsC, D, and E and the genes involved in exopolysaccharide I (EPSI) synthesis in Rhizobium meliloti for epsC to epsJ and the genes involved in lipopolysaccharide synthesis in members of the Enterobacteriaceae, and finally for eps K and lipB of Neisseria meningitidis. Genes (epsJ, epsL, and epsM) for which the predicted proteins showed little or no homology with proteins in the Swiss-Prot database were shown to be involved in EPS synthesis by single-crossover gene disruption experiments.
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Affiliation(s)
- F Stingele
- Nestlé Research Center, Nestec Ltd., Lausanne, Switzerland
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83
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Arrecubieta C, García E, López R. Sequence and transcriptional analysis of a DNA region involved in the production of capsular polysaccharide in Streptococcus pneumoniae type 3. Gene 1995; 167:1-7. [PMID: 8566758 DOI: 10.1016/0378-1119(95)00657-5] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The nucleotide (nt) sequence of a 9704-bp EcoRI fragment of Streptococcus pneumoniae (Sp) type-3 DNA has been determined and found to contain one partial and five complete open reading frames (ORFs). One of these ORFs corresponds to the cap3 A gene coding for the UDP-glucose (UDPGlc) dehydrogenase which is directly responsible for the transformation of some unencapsulated serotype-3 Sp mutants to the encapsulated phenotype [Arrecubieta et al., J. Bacteriol. 176 (1994) 6375-6383]. The two ORFs downstream from this gene (cap3B and cap3C) encode proteins with molecular masses of 49 and 34 kDa. Analysis of the deduced amino acid (aa) sequences of Cap3B and Cap3C shows homology to polysaccharide synthases and UDPG1c pyrophosphorylases, respectively. Furthermore, genetic complementation analysis showed that cap3C restored the galU defect of an Escherichia coli mutant. Northern blots have shown that cap3A, cap3B and cap3C constitute a single transcriptional unit, and primer extension analysis has revealed that the transcription start point is preceded by a nt sequence identical to the sigma 70 consensus promoter sequence of E. coli. The sequence upstream from this cluster also has a high degree of similarity with genes postulated to be essential for capsular production in several Gram+ bacteria. However, Northern blot analysis and insertion-duplication mutagenesis indicated that genes located in this region are not necessary for type-3 capsule production in the Sp strain 406.
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Affiliation(s)
- C Arrecubieta
- Departamento de Microbiología Molecular, Centro de Investigaciones Biológicas, CSIC, Madrid, Spain
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84
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Zuber M, Hoover TA, Court DL. Analysis of a Coxiella burnetti gene product that activates capsule synthesis in Escherichia coli: requirement for the heat shock chaperone DnaK and the two-component regulator RcsC. J Bacteriol 1995; 177:4238-44. [PMID: 7635811 PMCID: PMC177168 DOI: 10.1128/jb.177.15.4238-4244.1995] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
A 1.2-kb EcoRI genomic DNA fragment of Coxiella burnetti, when cloned onto a multicopy plasmid, was found to induce capsule synthesis (mucoidy) in Escherichia coli. Nucleotide sequence analysis revealed the presence of an open reading frame that could encode a protein of 270 amino acids. Insertion of a tet cassette into a unique NruI restriction site resulted in the loss of induction of mucoidy. Because of its ability to induce mucoidy, we designated this gene mucZ. Computer search for homologies to mucZ revealed 42% identity to an open reading frame located at 1 min of the E. coli chromosome. Interestingly, the C-terminal amino acid residues of MucZ share significant homology with the J domain of the DnaJ protein and its homologs, suggesting potential interactions between MucZ and components of the DnaK-chaperone machinery. Results presented in this paper suggest that E. coli requires DnaK-chaperone machinery for Lon-RcsA-mediated induction of capsule synthesis, as noticed first by S. Gottesman (personal communication). The induction caused by MucZ is independent of Lon-RcsA and is mediated through the two-component regulators RcsC and RcsB. DnaK and GrpE but not DnaJ are also required for the RcsB-mediated MucZ induction, and we propose that MucZ is a DnaJ-like chaperone protein that might be required for the formation of an active RcsA-RcsB complex and for the RcsC-dependent phosphorylation of RcsB. Discussions are presented that suggest three different roles for alternative forms of the DnaK-chaperone machinery in capsule production.
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Affiliation(s)
- M Zuber
- Toxinology Division, U.S. Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland 21702-5011, USA
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85
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Huang J, Schell M. Molecular characterization of the eps gene cluster of Pseudomonas solanacearum and its transcriptional regulation at a single promoter. Mol Microbiol 1995; 16:977-89. [PMID: 7476194 DOI: 10.1111/j.1365-2958.1995.tb02323.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Production of EPS I, an unusual exopolysaccharide virulence factor of the phytopathogen Pseudomonas solanacearum, requires the 18 kb eps gene cluster. DNA sequence analysis of the first seven genes of eps (epsAPBCDEF), subcellular localization of their products in maxicells, and phoA fusion analysis showed that: (i) epsA, epsB, epsE, and epsF encode exported or membrane-associated proteins probably involved in polymerization and/or export of EPS I; (ii) epsC and epsD encode soluble enzymes probably involved in synthesis of sugar components of EPS I (N-acetylgalactosaminuronic acid and possibly N-acetyltrideoxygalactose, respectively); and (iii) epsP probably encodes a phosphatase involved in EPS I production in an unknown way. Non-polar insertional mutagenesis showed that most, if not all, of these eps genes are absolutely required for production of EPS I. Using random eps::lacZ fusions and primer extension we located a transcription start site and promoter upstream of epsA. Analysis of a plasmid with this promoter fused to lacZ showed that a 140 bp regulatory region upstream of the eps transcription start site was sufficient for normal regulation of eps transcription by the multicomponent virulence gene regulatory network of P. solanacearum. Deletion of this eps promoter from a plasmid-borne epsAPBCDE::lacZ fusion reduced its expression 10-fold, indicating that this promoter alone is responsible for regulated transcription of an eps operon composed of at least epsAPBCDE. Analysis of genomic and plasmid-borne eps::lacZ fusions suggested that most remaining eps genes are part of this same operon or, and this is less likely, comprise a second co-ordinately regulated eps operon.
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Affiliation(s)
- J Huang
- Department of Microbiology, University of Georgia, Athens 30602, USA
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86
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Genco CA, Schifferle RE, Njoroge T, Forng RY, Cutler CW. Resistance of a Tn4351-generated polysaccharide mutant of Porphyromonas gingivalis to polymorphonuclear leukocyte killing. Infect Immun 1995; 63:393-401. [PMID: 7822002 PMCID: PMC173008 DOI: 10.1128/iai.63.2.393-401.1995] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
In this study, we describe the development of an efficient transpositional mutagenesis system for Porphyromonas gingivalis using the Bacteroides fragilis transposon Tn4351. Using this system, we have isolated and characterized a Tn4351-generated mutant of P. gingivalis A7436, designated MSM-1, which exhibits enhanced resistance to polymorphonuclear leukocyte (PMN) phagocytosis and killing. P. gingivalis MSM-1 was initially selected based on its colony morphology; MSM-1 appeared as a mucoid, beige-pigmented colony. Analysis of P. gingivalis MSM-1 by electron microscopy and staining with ruthenium red revealed the presence of a thick ruthenium red-staining layer that was twice the thickness of this layer observed in the parent strain. P. gingivalis MSM-1 was found to be more hydrophilic than strain A7436 by hydrocarbon partitioning. Analysis of phenol-water extracts prepared from P. gingivalis A7436 and MSM-1 by Western (immunoblot) analysis and immunodiffusion with hyperimmune sera raised against A7436 and MSM-1 revealed the loss of a high-molecular-weight anionic polysaccharide component in extracts prepared from MSM-1. P. gingivalis MSM-1 was also found to be more resistant to PMN phagocytosis and intracellular killing than the parent strain, as assessed in a fluorochrome phagocytosis microassay. These differences were statistically significant (P < 0.05) when comparing PMN phagocytosis in nonimmune serum and intracellular killing in nonimmune and immune sera. P. gingivalis MSM-1 was also more resistant to killing by crude granule extracts from PMNs than was P. gingivalis A7436. These results indicate that the increased evasion of PMN phagocytosis and killing exhibited by P. gingivalis MSM-1 may result from alterations in polysaccharide-containing antigens.
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Affiliation(s)
- C A Genco
- Department of Microbiology and Immunology, Morehouse School of Medicine, Atlanta, Georgia 30310
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87
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Guidolin A, Morona JK, Morona R, Hansman D, Paton JC. Nucleotide sequence analysis of genes essential for capsular polysaccharide biosynthesis in Streptococcus pneumoniae type 19F. Infect Immun 1994; 62:5384-96. [PMID: 7960118 PMCID: PMC303279 DOI: 10.1128/iai.62.12.5384-5396.1994] [Citation(s) in RCA: 99] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Previous studies have shown that the capsular polysaccharide synthesis (cps) locus of the type 19F Streptococcus pneumoniae strain SSZ was closely linked to a copy of the insertion sequence IS1202 (J.K. Morona, A. Guidolin, R. Morona, D. Hansman, and J.C. Paton, J. Bacteriol. 176:4437-4443, 1994). In the present study, we used plasmid insertion and rescue and inverse PCR to clone 6,322 bp of flanking DNA upstream of IS1202. Sequence analysis indicated that this region contains six complete open reading frames (ORFs) and one partial ORF that are arranged as a single transcriptional unit. Chromosomal disruption of any of these ORFs in a smooth-type 19F strain leads to a rough (unencapsulated) phenotype, indicating that this operon is essential for capsule production. The ORFs have therefore been designated cps19fA to cps19fG, where cps19fA is the first gene of the type 19F cps locus. Furthermore, many of the gene products from this incomplete operon exhibit strong similarities to proteins known to be involved in the production of capsular polysaccharide, exopolysaccharide, teichoic acid, enterobacterial common antigen, and lipopolysaccharide from numerous other bacterial species. This has allowed us to propose functions for many of the type 19F cps gene products. Southern hybridization studies reveal that cps19fA and cps19fB are conserved among all 12 pneumococcal serotypes tested, whereas genes downstream of cps19fB are conserved among some, but not all, of the serotypes tested.
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Affiliation(s)
- A Guidolin
- Department of Microbiology, Women's and Children's Hospital, North Adelaide, Australia
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88
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Pollock TJ, Thorne L, Yamazaki M, Mikolajczak MJ, Armentrout RW. Mechanism of bacitracin resistance in gram-negative bacteria that synthesize exopolysaccharides. J Bacteriol 1994; 176:6229-37. [PMID: 7928993 PMCID: PMC196963 DOI: 10.1128/jb.176.20.6229-6237.1994] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Four representative species from three genera of gram-negative bacteria that secrete exopolysaccharides acquired resistance to the antibiotic bacitracin by stopping synthesis of the exopolysaccharide. Xanthomonas campestris, Sphingomonas strains S-88 and NW11, and Escherichia coli K-12 secrete xanthan gum, sphingans S-88 and NW11, and colanic acid, respectively. The gumD gene in X. campestris is required to attach glucose-P to C55-isoprenyl phosphate, the first step in the assembly of xanthan. A recombinant plasmid carrying the gumD gene of X. campestris restored polysaccharide synthesis to bacitracin-resistant exopolysaccharide-negative mutants of X. campestris and Sphingomonas strains. Similarly, a newly cloned gene (spsB) from strain S-88 restored xanthan synthesis to the same X. campestris mutants. However, the intergeneric complementation did not extend to mutants of E. coli that were both resistant to bacitracin and nonproducers of colanic acid. The genetic results also suggest mechanisms for assembling the sphingans which have commercial potential as gelling and viscosifying agents.
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89
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Arrecubieta C, López R, García E. Molecular characterization of cap3A, a gene from the operon required for the synthesis of the capsule of Streptococcus pneumoniae type 3: sequencing of mutations responsible for the unencapsulated phenotype and localization of the capsular cluster on the pneumococcal chromosome. J Bacteriol 1994; 176:6375-83. [PMID: 7929009 PMCID: PMC196979 DOI: 10.1128/jb.176.20.6375-6383.1994] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The complete nucleotide sequence of the cap3A gene of Streptococcus pneumoniae, which is directly responsible for the transformation of some unencapsulated, serotype 3 mutants to the encapsulated phenotype, has been determined. This gene encodes a protein of 394 amino acids with a predicted M(r) of 44,646. Twelve independent cap3A mutations have been mapped by genetic transformation, and three of them have been sequenced. Sequence comparisons revealed that cap3A was very similar (74.4%) to the hasB gene of Streptococcus pyogenes, which encodes a UDP-glucose dehydrogenase (UDP-GlcDH) that catalyzes the conversion of UDP-glucose to UDP-glucuronic acid, the donor substances in the pneumococcal type 3 capsular polysaccharide. Furthermore, a PCR-generated cap3A+ gene restored encapsulation in our cap3A mutants as well as in a mutant previously characterized as deficient in UDP-GlcDH (R. Austrian, H. P. Bernheimer, E.E.B. Smith, and G.T. Mills, J. Exp. Med. 110:585-602, 1959). These results support the conclusion that cap3A codes for UDP-GlcDH. We have also identified a region upstream of cap3A that should contain common genes necessary for the production of capsule of any type. Pulsed-field gel electrophoresis and Southern blotting showed that the capsular genes specific for serotype 3 are located near the genes encoding PBP 2X and PBP 1A in the S. pneumoniae chromosome, whereas copies of the common genes (or part of them) appear to be present in different locations in the genome.
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Affiliation(s)
- C Arrecubieta
- Departamento de Microbiología Molecular, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
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90
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Platt MW, Scaletti J, Correa N. The effects of growth in human serum on an acapsular group B Streptococcus mutant. FEMS IMMUNOLOGY AND MEDICAL MICROBIOLOGY 1994; 9:245-51. [PMID: 7812272 DOI: 10.1111/j.1574-695x.1994.tb00500.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A Group B Streptococcus Type III (GBS) mutant which, when grown in Todd Hewitt broth (THB), does not produce any detectable capsule, produced a clearly visible polysaccharide capsule when grown in human serum. We isolated cytoplasmic membranes from GBS and separated the component membrane proteins by polyacrylamide gel electrophoresis. A significant change in membrane composition was found during growth in human serum. Several unique proteins were produced on serum growth and there was both up- and down-regulation of other proteins. We measured the intracellular levels of sialic acid for a variety of GBS serotype III isolates. Interestingly, while there was little difference between the intracellular sialic levels of most isolates, the sialic acid level of COH31-15 grown in THB was over 100% higher than that of any other isolate. When grown in serum this pool was reduced to a level similar to that in other strains. The concentration of bacterial cell sialic acid was directly correlated with the sialic acid content of the serum. Exogenous sialic acid content, in concert with other serum factors, plays a role in determining the capsular size in GBS.
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Affiliation(s)
- M W Platt
- Department of Microbiology, School of Medicine, University of New Mexico, Albuquerque 87131
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91
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Ricci ML, Manganelli R, Berneri C, Orefici G, Pozzi G. Electrotransformation of Streptococcus agalactiae with plasmid DNA. FEMS Microbiol Lett 1994; 119:47-52. [PMID: 8039669 DOI: 10.1111/j.1574-6968.1994.tb06865.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
A protocol for efficient electrotransformation of Streptococcus agalactiae (group B streptococcus) Lancefield's strain O90R (NTCT 9993) (an unencapsulated derivative of type Ia strain O90) was developed. The Escherichia coli-Streptococcus shuttle vector pDP28 (7.8 kb) carrying the ermB gene for resistance to erythromycin was used as donor DNA. Frozen 'electrocompetent' cells were prepared by repeated washes in 10% glycerol. A 50-microliters aliquot containing about 5 x 10(9) colony forming units of bacteria was subjected to the electric pulse. Optimal conditions for electrotransformation were determined using different media, harvesting cells at different points of the growth curve, and using different field strengths. The dose-response curve for transformation of S. agalactiae with pDP28 showed one-hit kinetics as donor DNA varied between 0.01 and 3 micrograms. The efficiency of electrotransformation for this range of amounts of donor DNA was 1.2 x 10(4) cfu micrograms-1. The transformation frequencies obtained with this electroporation protocol are high enough to allow both subcloning and shotgun cloning of streptococcal DNA in S. agalactiae.
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Affiliation(s)
- M L Ricci
- Istituto Superiore di Sanità, Roma, Italy
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92
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Marques MB, Kasper DL, Shroff A, Michon F, Jennings HJ, Wessels MR. Functional activity of antibodies to the group B polysaccharide of group B streptococci elicited by a polysaccharide-protein conjugate vaccine. Infect Immun 1994; 62:1593-9. [PMID: 8168919 PMCID: PMC186360 DOI: 10.1128/iai.62.5.1593-1599.1994] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Group B streptococci (GBS) are a major cause of sepsis and meningitis in infants. While antibodies directed to the type-specific GBS capsule have been shown to be protective, it is less clear whether antibodies to the group B polysaccharide, a noncapsular, cell wall-associated antigen, may play a role in immunity. To investigate the functional activity of group B polysaccharide-specific antibodies, we tested sera from rabbits vaccinated with group B polysaccharide coupled to tetanus toxoid (B-TT). Anti-B-TT was weakly opsonic in vitro for a highly encapsulated type III strain, while antiserum elicited by vaccination with type III capsular polysaccharide linked to tetanus toxoid (III-TT) was a very effective opsonin. In contrast to anti-III-TT, anti-B-TT given before or after bacterial challenge was only marginally effective in protecting newborn mice against lethal infection with type III GBS. The number of C3 molecules bound to type III GBS was augmented by anti-III-TT but not by high antibody concentrations of anti-B-TT. These results suggest that the difference in opsonic activity between anti-B-TT and anti-III-TT may be due to a difference in their ability to deposit C3. In addition, the maximum number of antibody molecules bound to the bacterial surface was greater for anti-III-TT than for anti-B-TT. That anti-B-TT binds to fewer sites than anti-III-TT may explain the differences in complement activation and in opsonic and protective efficacy of antibodies to group B polysaccharide compared with antibodies to the type-specific capsular polysaccharide.
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Affiliation(s)
- M B Marques
- Channing Laboratory, Brigham and Women's Hospital, Boston, Massachusetts 02115
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93
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Hulse ML, Smith S, Chi EY, Pham A, Rubens CE. Effect of type III group B streptococcal capsular polysaccharide on invasion of respiratory epithelial cells. Infect Immun 1993; 61:4835-41. [PMID: 8406885 PMCID: PMC281241 DOI: 10.1128/iai.61.11.4835-4841.1993] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Group B streptococcal (GBS) capsular polysaccharide is an important virulence factor, and its role in invasion of cultured respiratory epithelial cells was investigated. A type III GBS clinical isolate, COH1, and asialo and unencapsulated isogenic transposon capsule mutants of it were compared in an in vitro invasion assay. The results demonstrated that capsule attenuated the invasion process. Invasion was not affected when the A549 epithelial cells were preincubated with purified type III GBS capsular polysaccharide. Polyclonal type III GBS capsule antibody inhibited invasion by COH1 but did not affect invasion by the capsule mutants. Serotypes Ia, Ib, Ia/c, II, and III all invaded respiratory epithelial cells but demonstrated some strain variation in magnitude of invasion. These observations led us to conclude that type III capsular polysaccharide was not essential for invasion of respiratory epithelial cells by GBS and that bacterial factors other than capsule were responsible for respiratory epithelial cell invasion.
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Affiliation(s)
- M L Hulse
- Department of Pediatrics, Children's Hospital and Medical Center, Seattle, Washington
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94
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Glucksmann MA, Reuber TL, Walker GC. Family of glycosyl transferases needed for the synthesis of succinoglycan by Rhizobium meliloti. J Bacteriol 1993; 175:7033-44. [PMID: 8226645 PMCID: PMC206831 DOI: 10.1128/jb.175.21.7033-7044.1993] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Rhizobium meliloti produces an acidic exopolysaccharide, termed succinoglycan or EPS I, that is important for invasion of the nodules that it elicits on its host, Medicago sativa. Succinoglycan is a high-molecular-weight polymer composed of repeating octasaccharide subunits. These subunits are synthesized on membrane-bound isoprenoid lipid carriers, beginning with a galactose residue followed by seven glucose residues, and modified by the addition of acetate, succinate, and pyruvate. Biochemical characterizations of lipid-linked succinoglycan biosynthetic intermediates from previously identified exo mutant strains have been carried out in our laboratory (T. L. Reuber and G. C. Walker, Cell 74:269-280, 1993) to determine where each mutation blocks the biosynthetic pathway. We have carried out a fine structure genetic analysis of a portion of the cluster of exo genes present on the second symbiotic megaplasmid of R. meliloti and have identified several new genes. In addition, the DNA sequence of 16 kb of the exo cluster was determined and the genetic map was correlated with the DNA sequence. In this paper we present the sequence of a family of glycosyl transferases required for the synthesis of succinoglycan and discuss their functions.
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Affiliation(s)
- M A Glucksmann
- Department of Biology, Massachusetts Institute of Technology, Cambridge 02139
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