1
|
Liu B, Mashimo C, Nambu T, Maruyama H, Okinaga T. Transposon insertion in Rothia dentocariosa. J Oral Biosci 2024; 66:358-364. [PMID: 38641252 DOI: 10.1016/j.job.2024.04.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Revised: 04/16/2024] [Accepted: 04/17/2024] [Indexed: 04/21/2024]
Abstract
OBJECTIVES Rothia spp. are emerging as significant bacteria associated with oral health, with Rothia dentocariosa being one of the most prevalent species. However, there is a lack of studies examining these properties at the genetic level. This study aimed to establish a genetic modification platform for R. dentocariosa. METHODS Rothia spp. were isolated from saliva samples collected from healthy volunteers. Subsequently, R. dentocariosa strains were identified through colony morphology, species-specific polymerase chain reaction (PCR), and 16S ribosomal RNA gene sequencing. The identified strains were then transformed with plasmid pJRD215, and the most efficient strain was selected. Transposon insertion mutagenesis was performed to investigate the possibility of genetic modifications. RESULTS A strain demonstrating high transforming ability, designated as R. dentocariosa LX16, was identified. This strain underwent transposon insertion mutagenesis and was screened for 5-fluoroorotic acid-resistant transposants. The insertion sites were confirmed using arbitrary primed PCR, gene-specific PCR, and Sanger sequencing. CONCLUSION This study marks the first successful genetic modification of R. dentocariosa. Investigating R. dentocariosa at the genetic level can provide insights into its role within the oral microbiome.
Collapse
Affiliation(s)
- Boang Liu
- Department of Bacteriology, Graduate School of Dentistry, Osaka Dental University, Japan
| | - Chiho Mashimo
- Department of Bacteriology, Osaka Dental University, Japan.
| | - Takayuki Nambu
- Department of Bacteriology, Osaka Dental University, Japan
| | - Hugo Maruyama
- Department of Bacteriology, Osaka Dental University, Japan
| | | |
Collapse
|
2
|
Bhat AH, Das A, Ton-That H. Single-Copy Gene Editing of a Cell Wall-Anchored Pilin in Actinomyces oris. Methods Mol Biol 2024; 2727:125-134. [PMID: 37815713 DOI: 10.1007/978-1-0716-3491-2_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/11/2023]
Abstract
The Gram-positive bacterium Actinomyces oris expresses a unique cell wall-anchored fimbria comprised of the fimbrial shaft FimA and the tip fimbrillin CafA, whose gene is not genetically linked to the fimA locus, unlike many other fimbrial gene loci in Gram-positive bacteria. Mutational analyses of individual fimbrillins, FimA and CafA, in A. oris often rely on multi-copy plasmids that may alter the stoichiometry of fimbrillins in vivo, hence fimbrial assembly. Here, we provide a robust method for single-copy gene expression and mutagenesis in A. oris, using CafA as an experimental model. This method can be applied for single-copy gene editing in various bacterial systems.
Collapse
Affiliation(s)
- Aadil H Bhat
- Division of Oral & Systemic Health Sciences, School of Dentistry, University of California, Los Angeles, CA, USA
| | - Asis Das
- Department of Medicine, Neag Comprehensive Cancer Center, University of Connecticut Health Center, Farmington, CT, USA
| | - Hung Ton-That
- Division of Oral & Systemic Health Sciences, School of Dentistry, University of California, Los Angeles, CA, USA.
- Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles, Los Angeles, CA, USA.
- Molecular Biology Institute, University of California, Los Angeles, CA, USA.
| |
Collapse
|
3
|
Merritt J, Kreth J. Illuminating the oral microbiome and its host interactions: tools and approaches for molecular microbiology studies. FEMS Microbiol Rev 2023; 47:fuac050. [PMID: 36549660 PMCID: PMC10719069 DOI: 10.1093/femsre/fuac050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022] Open
Abstract
Advancements in DNA sequencing technologies within the last decade have stimulated an unprecedented interest in the human microbiome, largely due the broad diversity of human diseases found to correlate with microbiome dysbiosis. As a direct consequence of these studies, a vast number of understudied and uncharacterized microbes have been identified as potential drivers of mucosal health and disease. The looming challenge in the field is to transition these observations into defined molecular mechanistic studies of symbiosis and dysbiosis. In order to meet this challenge, many of these newly identified microbes will need to be adapted for use in experimental models. Consequently, this review presents a comprehensive overview of the molecular microbiology tools and techniques that have played crucial roles in genetic studies of the bacteria found within the human oral microbiota. Here, we will use specific examples from the oral microbiome literature to illustrate the biology supporting these techniques, why they are needed in the field, and how such technologies have been implemented. It is hoped that this information can serve as a useful reference guide to help catalyze molecular microbiology studies of the many new understudied and uncharacterized species identified at different mucosal sites in the body.
Collapse
Affiliation(s)
- Justin Merritt
- Department of Restorative Dentistry, School of Dentistry, Oregon Health and Science University, Portland, OR, United States
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR 97239, United States
| | - Jens Kreth
- Department of Restorative Dentistry, School of Dentistry, Oregon Health and Science University, Portland, OR, United States
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR 97239, United States
| |
Collapse
|
4
|
Exploitation of a Bacterium-Encoded Lytic Transglycosylase by a Human Oral Lytic Phage To Facilitate Infection. J Virol 2022; 96:e0106322. [PMID: 36000841 PMCID: PMC9472602 DOI: 10.1128/jvi.01063-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Bacteriophages (phages) are an integral part of the human oral microbiome. Their roles in modulating bacterial physiology and shaping microbial communities have been discussed but remain understudied due to limited isolation and characterization of oral phage. Here, we report the isolation of LC001, a lytic phage targeting human oral Schaalia odontolytica (formerly known as Actinomyces odontolyticus) strain XH001. We showed that LC001 attached to and infected surface-grown, but not planktonic, XH001 cells, and it displayed remarkable host specificity at the strain level. Whole-genome sequencing of spontaneous LC001-resistant, surface-grown XH001 mutants revealed that the majority of the mutants carry nonsense or frameshift mutations in XH001 gene APY09_05145 (renamed ltg-1), which encodes a putative lytic transglycosylase (LT). The mutants are defective in LC001 binding, as revealed by direct visualization of the significantly reduced attachment of phage particles to the XH001 spontaneous mutants compared that to the wild type. Meanwhile, targeted deletion of ltg-1 produced a mutant that is defective in LC001 binding and resistant to LC001 infection even as surface-grown cells, while complementation of ltg-1 in the mutant background restored the LC001-sensitive phenotype. Intriguingly, similar expression levels of ltg-1 were observed in surface-grown and planktonic XH001, which displayed LC001-binding and nonbinding phenotypes, respectively. Furthermore, the overexpression of ltg-1 failed to confer an LC001-binding and -sensitive phenotype to planktonic XH001. Thus, our data suggested that rather than directly serving as a phage receptor, ltg-1-encoded LT may increase the accessibility of phage receptor, possibly via its enzymatic activity, by cleaving the peptidoglycan structure for better receptor exposure during peptidoglycan remodeling, a function that can be exploited by LC001 to facilitate infection. IMPORTANCE The evidence for the presence of a diverse and abundant phage population in the host-associated oral microbiome came largely from metagenomic analysis or the observation of virus-like particles within saliva/plaque samples, while the isolation of oral phage and investigation of their interaction with bacterial hosts are limited. Here, we report the isolation of LC001, the first lytic phage targeting oral Schaalia odontolytica. Our study suggested that LC001 may exploit the host bacterium-encoded lytic transglycosylase function to gain access to the receptor, thus facilitating its infection.
Collapse
|
5
|
The human microbiome encodes resistance to the antidiabetic drug acarbose. Nature 2021; 600:110-115. [PMID: 34819672 DOI: 10.1038/s41586-021-04091-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 10/01/2021] [Indexed: 12/26/2022]
Abstract
The human microbiome encodes a large repertoire of biochemical enzymes and pathways, most of which remain uncharacterized. Here, using a metagenomics-based search strategy, we discovered that bacterial members of the human gut and oral microbiome encode enzymes that selectively phosphorylate a clinically used antidiabetic drug, acarbose1,2, resulting in its inactivation. Acarbose is an inhibitor of both human and bacterial α-glucosidases3, limiting the ability of the target organism to metabolize complex carbohydrates. Using biochemical assays, X-ray crystallography and metagenomic analyses, we show that microbiome-derived acarbose kinases are specific for acarbose, provide their harbouring organism with a protective advantage against the activity of acarbose, and are widespread in the microbiomes of western and non-western human populations. These results provide an example of widespread microbiome resistance to a non-antibiotic drug, and suggest that acarbose resistance has disseminated in the human microbiome as a defensive strategy against a potential endogenous producer of a closely related molecule.
Collapse
|
6
|
Arai T, Aikawa S, Sudesh K, Kondo T, Kosugi A. Electrotransformation of thermophilic bacterium Caldimonas manganoxidans. J Microbiol Methods 2021; 192:106375. [PMID: 34793853 DOI: 10.1016/j.mimet.2021.106375] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/12/2021] [Accepted: 11/12/2021] [Indexed: 12/22/2022]
Abstract
Caldimonas manganoxidans is a Gram-negative, thermophilic, bioplastic-producing bacterium that is a promising strain to overcome the drawbacks of existing bioplastic manufacturing methods. However, genetic manipulation of this species has not previously been studied. Here, we developed an optimized electrotransformation protocol for C. manganoxidans by screening conditions, including the bacterial growth phase, electroporation buffer, pulse strength, and recovery time. The optimized transformation protocol obtained (3.1 ± 0.78) × 108 colony-forming units/μg DNA of plasmid pBBR1MCS-2. High transformation efficiency was observed when using plasmid DNA isolated from C. manganoxidans. The DNA methylases of Escherichia coli did not affect the transformation efficiency of C. manganoxidans. The electrotransformation technique proposed here will be beneficial for the genetic manipulation of thermophilic Caldimonas species.
Collapse
Affiliation(s)
- Takamitsu Arai
- Japan International Research Center for Agricultural Sciences, 1-1 Ohwashi Tsukuba, Ibaraki 305-8686, Japan
| | - Shimpei Aikawa
- Japan International Research Center for Agricultural Sciences, 1-1 Ohwashi Tsukuba, Ibaraki 305-8686, Japan
| | - Kumar Sudesh
- School of Biological Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia
| | - Toshiaki Kondo
- Japan International Research Center for Agricultural Sciences, 1-1 Ohwashi Tsukuba, Ibaraki 305-8686, Japan
| | - Akihiko Kosugi
- Japan International Research Center for Agricultural Sciences, 1-1 Ohwashi Tsukuba, Ibaraki 305-8686, Japan.
| |
Collapse
|
7
|
Bedree JK, Bor B, Cen L, Edlund A, Lux R, McLean JS, Shi W, He X. Quorum Sensing Modulates the Epibiotic-Parasitic Relationship Between Actinomyces odontolyticus and Its Saccharibacteria epibiont, a Nanosynbacter lyticus Strain, TM7x. Front Microbiol 2018; 9:2049. [PMID: 30319555 PMCID: PMC6166536 DOI: 10.3389/fmicb.2018.02049] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 08/13/2018] [Indexed: 11/13/2022] Open
Abstract
The ultra-small, obligate parasitic epibiont, TM7x, the first and only current member of the long-elusive Saccharibacteria (formerly the TM7 phylum) phylum to be cultivated, was isolated in co-culture with its bacterial host, Actinomyces odontolyticus subspecies actinosynbacter, XH001. Initial phenotypic characterization of the TM7x-associated XH001 co-culture revealed enhanced biofilm formation in the presence of TM7x compared to XH001 as monoculture. Genomic analysis and previously published transcriptomic profiling of XH001 also revealed the presence of a putative AI-2 quorum sensing (QS) operon, which was highly upregulated upon association of TM7x with XH001. This analysis revealed that the most highly induced gene in XH001 was an lsrB ortholog, which encodes a putative periplasmic binding protein for the auto inducer (AI)-2 QS signaling molecule. Further genomic analyses suggested the lsrB operon in XH001 is a putative hybrid AI-2/ribose transport operon as well as the existence of a luxS ortholog, which encodes the AI-2 synthase. In this study, the potential role of AI-2 QS in the epibiotic-parasitic relationship between XH001 and TM7x in the context of biofilm formation was investigated. A genetic system for XH001 was developed to generate lsrB and luxS gene deletion mutants in XH001. Phenotypic characterization demonstrated that deletion mutations in either lsrB or luxS did not affect XH001's growth dynamic, mono-species biofilm formation capability, nor its ability to associate with TM7x. TM7x association with XH001 induced lsrB gene expression in a luxS-dependent manner. Intriguingly, unlike wild type XH001, which displayed significantly increased biofilm formation upon establishing the epibiotic-parasitic relationship with TM7x, XH001ΔlsrB, and XH001ΔluxS mutants failed to achieve enhanced biofilm formation when associated with TM7x. In conclusion, we demonstrated a significant role for AI-2 QS in modulating dual-species biofilm formation when XH001 and TM7x establish their epibiotic-parasitic relationship.
Collapse
Affiliation(s)
- Joseph K Bedree
- Section of Oral Biology, Division of Oral Biology and Medicine, School of Dentistry, University of California, Los Angeles, Los Angeles, CA, United States.,Department of Microbiology, The Forsyth Institute, Cambridge, MA, United States
| | - Batbileg Bor
- Department of Microbiology, The Forsyth Institute, Cambridge, MA, United States
| | - Lujia Cen
- Department of Microbiology, The Forsyth Institute, Cambridge, MA, United States
| | - Anna Edlund
- Department of Genomic Medicine, J. Craig Venter Institute, La Jolla, CA, United States
| | - Renate Lux
- Section of Periodontics, Division of Constitutive and Regenerative Sciences, School of Dentistry, University of California, Los Angeles, Los Angeles, CA, United States
| | - Jeffrey S McLean
- Department of Periodontics, School of Dentistry, University of Washington, Seattle, WA, United States
| | - Wenyuan Shi
- Department of Microbiology, The Forsyth Institute, Cambridge, MA, United States
| | - Xuesong He
- Department of Microbiology, The Forsyth Institute, Cambridge, MA, United States
| |
Collapse
|
8
|
Abstract
Sortase is a cysteine-transpeptidase that anchors LPXTG-containing proteins on the Gram-positive bacterial cell wall. Previously, sortase was considered to be an important factor for bacterial pathogenesis and fitness, but not cell growth. However, the Actinomyces oris sortase is essential for cell viability, due to its coupling to a glycosylation pathway. In this chapter, we describe the methods to generate conditional srtA deletion mutants and identify srtA suppressors by Tn5 transposon mutagenesis. We also provide procedures for analyzing cell morphology of this mutant by thin-section electron microscopy. These techniques can be applied for analyses of other essential genes in A. oris.
Collapse
|
9
|
Mulé MP, Giacalone D, Lawlor K, Golden A, Cook C, Lott T, Aksten E, O'Toole GA, Bergeron LJ. Iron-dependent gene expression in Actinomyces oris. J Oral Microbiol 2015; 7:29800. [PMID: 26685151 PMCID: PMC4684579 DOI: 10.3402/jom.v7.29800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 11/20/2015] [Accepted: 11/23/2015] [Indexed: 11/21/2022] Open
Abstract
Background Actinomyces oris is a Gram-positive bacterium that has been associated with healthy and diseased sites in the human oral cavity. Most pathogenic bacteria require iron to survive, and in order to acquire iron in the relatively iron-scarce oral cavity A. oris has been shown to produce iron-binding molecules known as siderophores. The genes encoding these siderophores and transporters are thought to be regulated by the amount of iron in the growth medium and by the metal-dependent repressor, AmdR, which we showed previously binds to the promoter of proposed iron-regulated genes. Objective The purpose of this study was to characterize siderophore and associated iron transport systems in A. oris.
Design We examined gene expression of the putative iron transport genes fetA and sidD in response to low- and high-iron environments. One of these genes, sidD, encoding a putative Fe ABC transporter protein, was insertionally inactivated and was examined for causing growth defects. To gain a further understanding of the role of iron metabolism in oral diseases, clinical isolates of Actinomyces spp. were examined for the presence of the gene encoding AmdR, a proposed global regulator of iron-dependent gene expression in A. oris.
Results When A. oris was grown under iron-limiting conditions, the genes encoding iron/siderophore transporters fetA and sidD showed increased expression. One of these genes (sidD) was mutated, and the sidD::Km strain exhibited a 50% reduction in growth in late log and stationary phase cells in media that contained iron. This growth defect was restored when the sidD gene was provided in a complemented strain. We were able to isolate the AmdR-encoding gene in seven clinical isolates of Actinomyces. When these protein sequences were aligned to the laboratory strain, there was a high degree of sequence similarity. Conclusions The growth of the sidD::Km mutant in iron-replete medium mirrored the growth of the wild-type strain grown in iron-limiting medium, suggesting that the sidD::Km mutant was compromised in iron uptake. The known iron regulator AmdR is well conserved in clinical isolates of A. oris. This work provides additional insight into iron metabolism in this important oral microbe.
Collapse
Affiliation(s)
- Matthew P Mulé
- Department of Biology, New England College, Henniker, NH, USA
| | - David Giacalone
- Department of Biology, New England College, Henniker, NH, USA
| | - Kayla Lawlor
- Department of Biology, New England College, Henniker, NH, USA
| | - Alexa Golden
- Department of Biology, New England College, Henniker, NH, USA
| | - Caroline Cook
- Department of Biology, New England College, Henniker, NH, USA
| | - Thomas Lott
- Department of Biology, New England College, Henniker, NH, USA
| | | | - George A O'Toole
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
| | - Lori J Bergeron
- Department of Biology, New England College, Henniker, NH, USA;
| |
Collapse
|
10
|
Wu C, Huang IH, Chang C, Reardon-Robinson ME, Das A, Ton-That H. Lethality of sortase depletion in Actinomyces oris caused by excessive membrane accumulation of a surface glycoprotein. Mol Microbiol 2014; 94:1227-41. [PMID: 25230351 DOI: 10.1111/mmi.12780] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/29/2014] [Indexed: 01/03/2023]
Abstract
Sortase, a cysteine-transpeptidase conserved in Gram-positive bacteria, anchors on the cell wall many surface proteins that facilitate bacterial pathogenesis and fitness. Genetic disruption of the housekeeping sortase in several Gram-positive pathogens reported thus far attenuates virulence, but not bacterial growth. Paradoxically, we discovered that depletion of the housekeeping sortase SrtA was lethal for Actinomyces oris; yet, all of its predicted cell wall-anchored protein substrates (AcaA-N) were individually dispensable for cell viability. Using Tn5-transposon mutagenesis to identify factors that upend lethality of srtA deletion, we uncovered a set of genetic suppressors harbouring transposon insertions within genes of a locus encoding AcaC and a LytR-CpsA-Psr (LCP)-like protein. AcaC was shown to be highly glycosylated and dependent on LCP for its glycosylation. Upon SrtA depletion, the glycosylated form of AcaC, hereby renamed GspA, was accumulated in the membrane. Overexpression of GspA in a mutant lacking gspA and srtA was lethal; conversely, cells overexpressing a GspA mutant missing a membrane-localization domain were viable. The results reveal a unique glycosylation pathway in A. oris that is coupled to cell wall anchoring catalysed by sortase SrtA. Significantly, this novel phenomenon of glyco-stress provides convenient cell-based assays for developing a new class of inhibitors against Gram-positive pathogens.
Collapse
Affiliation(s)
- Chenggang Wu
- Department of Microbiology & Molecular Genetics, University of Texas Health Science Center, Houston, TX, USA
| | | | | | | | | | | |
Collapse
|
11
|
Abstract
Recent progress in molecular biology and genetics opens up the possibility of engineering a variety of biological systems, from single-cellular to multicellular organisms. The consortia of microbes that reside on the human body, the human-associated microbiota, are particularly interesting as targets for forward engineering and manipulation due to their relevance in health and disease. New technologies in analysis and perturbation of the human microbiota will lead to better diagnostic and therapeutic strategies against diseases of microbial origin or pathogenesis. Here, we discuss recent advances that are bringing us closer to realizing the true potential of an engineered human-associated microbial community.
Collapse
Affiliation(s)
- Stephanie J Yaung
- Program in Medical Engineering Medical Physics, Harvard-MIT Health Sciences and Technology, Cambridge, MA, USA
| | | | | |
Collapse
|
12
|
Chen P, Leung KP. Identification of the srtC1 transcription start site and catalytically essential residues required for Actinomyces oris T14V SrtC1 activity. FEMS Microbiol Lett 2011; 322:115-22. [DOI: 10.1111/j.1574-6968.2011.02338.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
|
13
|
Delisle AL, Donkersloot JA. Relationships amongActinomyces naeslundii (A. viscosus)Bacteriophages Isolated from Sewage and the Oral Cavity. MICROBIAL ECOLOGY IN HEALTH AND DISEASE 2009. [DOI: 10.3109/08910609509140089] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Allan L. Delisle
- Department of Microbiology, School of Dentistry, University of Maryland at Baltimore, Baltimore, MD, 21201, USA
| | - Jacob A. Donkersloot
- Laboratory of Microbial Ecology, National Institute of Dental Research, National Institutes of Health, Bethesda, MD, 20892, USA
| |
Collapse
|
14
|
Chen P, Cisar JO, Hess S, Ho JTC, Leung KP. Amended description of the genes for synthesis of Actinomyces naeslundii T14V type 1 fimbriae and associated adhesin. Infect Immun 2007; 75:4181-5. [PMID: 17485454 PMCID: PMC1952015 DOI: 10.1128/iai.01955-06] [Citation(s) in RCA: 12] [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 type 1 fimbriae of Actinomyces naeslundii T14V mediate adhesion of this gram-positive species to the tooth surface. The present findings show that the locus for type 1 fimbria production in this strain includes three genes, fimQ for a minor fimbrial subunit that appears to be an adhesin, fimP for the major structural subunit, and srtC1 for a type 1 fimbria-specific sortase involved in the assembly of these structures.
Collapse
Affiliation(s)
- Ping Chen
- Microbiology Branch, U.S. Army Dental and Trauma Research Detachment, 310B B Street, Great Lakes, IL 60088, USA
| | | | | | | | | |
Collapse
|
15
|
Mishra A, Das A, Cisar JO, Ton-That H. Sortase-catalyzed assembly of distinct heteromeric fimbriae in Actinomyces naeslundii. J Bacteriol 2007; 189:3156-65. [PMID: 17277070 PMCID: PMC1855841 DOI: 10.1128/jb.01952-06] [Citation(s) in RCA: 79] [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
Two types of adhesive fimbriae are expressed by Actinomyces; however, the architecture and the mechanism of assembly of these structures remain poorly understood. In this study we characterized two fimbrial gene clusters present in the genome of Actinomyces naeslundii strain MG-1. By using immunoelectron microscopy and biochemical analysis, we showed that the fimQ-fimP-srtC1-fimR gene cluster encodes a fimbrial structure (designated type 1) that contains a major subunit, FimP, forming the shaft and a minor subunit, FimQ, located primarily at the tip. Similarly, the fimB-fimA-srtC2 gene cluster encodes a distinct fimbrial structure (designated type 2) composed of a shaft protein, FimA, and a tip protein, FimB. By using allelic exchange, we constructed an in-frame deletion mutant that lacks the SrtC2 sortase. This mutant produces abundant type 1 fimbriae and expresses the monomeric FimA and FimB proteins, but it does not assemble type 2 fimbriae. Thus, SrtC2 is a fimbria-specific sortase that is essential for assembly of the type 2 fimbriae. Together, our experiments pave the way for several lines of molecular investigation that are necessary to elucidate the fimbrial assembly pathways in Actinomyces and their function in the pathogenesis of different biofilm-related oral diseases.
Collapse
Affiliation(s)
- Arunima Mishra
- Department of Molecular, Microbial, and Structural Biology, University of Connecticut Health Center, 263 Farmington Ave., Farmington, CT 06030, USA
| | | | | | | |
Collapse
|
16
|
Abstract
Haemophilus influenzae is a fastidious Gram-negative coccobacilli that is a common commensal in the human upper respiratory tract. However, certain strains of this bacterium, including those considered to be nontypeable (NTHi), can cause human diseases ranging from otitis media to meningitis. Although naturally competent, NTHi take up plasmids by transformation very inefficiently, if at all. Many clinical isolates have also proven refractory to the introduction of currently available shuttle vectors via electroporation. Further, it has been difficult to determine protein expression from these vectors, unless specific antisera has been raised or a phenotype conferred. To address these problems, we have designed and constructed a set of broad host range vectors that are transferable via intergeneric conjugation with an Escherichia coli strain carrying chromosomally-encoded transfer functions. These vectors provide a site for cloning promoter::MCS regions and carry genes encoding resistance to one of two different antibiotics. This conjugal system allows the expression of marker genes in NTHi strains, enabling researchers to track the microbe's progress either in vivo using the infant rat model of infection, or in vitro through invasions of human tissue culture cell lines.
Collapse
Affiliation(s)
- D A Daines
- Department of Molecular Microbiology and Immunology. University of Missouri - Columbia, M616 Medical Science Building, DCO44.00, Columbia, MO 65212, USA.
| | | |
Collapse
|
17
|
Bergeron LJ, Burne RA. Roles of fructosyltransferase and levanase-sucrase of Actinomyces naeslundii in fructan and sucrose metabolism. Infect Immun 2001; 69:5395-402. [PMID: 11500409 PMCID: PMC98649 DOI: 10.1128/iai.69.9.5395-5402.2001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2001] [Accepted: 05/23/2001] [Indexed: 11/20/2022] Open
Abstract
The ability of Actinomyces naeslundii to convert sucrose to extracellular homopolymers of fructose and to catabolize these types of polymers is suspected to be a virulence trait that contributes to the initiation and progression of dental caries and periodontal diseases. Previously, we reported on the isolation and characterization of the gene, ftf, encoding the fructosyltransferase (FTF) of A. naeslundii WVU45. Allelic exchange mutagenesis was used to inactivate ftf, revealing that FTF-deficient stains were completely devoid of the capacity to produce levan-type (beta2,6-linked) polysaccharides. A polyclonal antibody was raised to a histidine-tagged, purified A. naeslundii FTF, and the antibody was used to localize the enzyme in the supernatant fluid. A sensitive technique was developed to detect levan formation by proteins that had been separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the method was used to confirm that the levan-synthesizing activity of A. naeslundii existed predominantly in a cell-free form, that a small amount of the activity was cell associated, and that the ftf mutant was unable to produce levans. By using the nucleotide sequence of the levanase gene of a genospecies 2 A. naeslundii, formerly Actinomyces viscosus, a portion of a homologue of this gene (levJ) was amplified by PCR and inserted into a suicide vector, and the resulting construct was used to inactivate the levJ gene in the genospecies 1 strain WVU45. A variety of physiologic and biochemical studies were performed on the wild-type and LevJ-deficient strains to demonstrate that (i) this enzyme was the dominant levanase and sucrase of A. naeslundii; (ii) that LevJ was inducible by growth in sucrose; (iii) that the LevJ activity was found predominantly (>90%) in a cell-associated form; and (iv) that there was a second, fructose-inducible fructan hydrolase activity produced by these strains. The data provide the first detailed molecular analysis of fructan production and catabolism in this abundant and important oral bacterium.
Collapse
Affiliation(s)
- L J Bergeron
- Center for Oral Biology and Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
| | | |
Collapse
|
18
|
Abstract
Oral microbial-plaque communities are biofilms composed of numerous genetically distinct types of bacteria that live in close juxtaposition on host surfaces. These bacteria communicate through physical interactions called coaggregation and coadhesion, as well as other physiological and metabolic interactions. Streptococci and actinomyces are the major initial colonizers of the tooth surface, and the interactions between them and their substrata help establish the early biofilm community. Fusobacteria play a central role as physical bridges that mediate coaggregation of cells and as physiological bridges that promote anaerobic microenvironments which protect coaggregating strict anaerobes in an aerobic atmosphere. New technologies for investigating bacterial populations with 16S rDNA probes have uncovered previously uncultured bacteria and have offered an approach to in situ examination of the spatial arrangement of the participant cells in oral-plaque biofilms. Flow cells with saliva-coated surfaces are particularly useful for studies of biofilm formation and observation. The predicted sequential nature of colonization of the tooth surface by members of different genera can be investigated by using these new technologies and imaging the cells in situ with confocal scanning laser microscopy. Members of at least seven genera now can be subjected to genetic studies owing to the discovery of gene-transfer systems in these genera. Identification of contact-inducible genes in streptococci offers an avenue to explore bacterial responses to their environment and leads the way toward understanding communication among inhabitants of a multispecies biofilm.
Collapse
Affiliation(s)
- P E Kolenbrander
- Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland 20892, USA.
| |
Collapse
|
19
|
Morou-Bermudez E, Burne RA. Analysis of urease expression in Actinomyces naeslundii WVU45. Infect Immun 2000; 68:6670-6. [PMID: 11083780 PMCID: PMC97765 DOI: 10.1128/iai.68.12.6670-6676.2000] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2000] [Accepted: 09/13/2000] [Indexed: 11/20/2022] Open
Abstract
The hydrolysis of urea by ureases of oral bacteria in dental plaque can cause a considerable increase in plaque pH, which can inhibit the development of dental caries. There is also indirect evidence that urea metabolism may promote the formation of calculus and that ammonia release from urea could exacerbate periodontal diseases. Actinomyces naeslundii, an early colonizer of the oral cavity and a numerically significant plaque constituent, demonstrates comparatively low levels of urease activity on isolation, so this organism has not been considered a major contributor to total oral urease activity. In this study it was observed that urease activity and urease-specific mRNA levels in A. naeslundii WVU45 can increase up to 50-fold during growth under nitrogen-limiting conditions. Using primer extension analysis, a putative, proximal, nitrogen-regulated promoter of the A. naeslundii urease gene cluster was identified. The functionality and nitrogen responsiveness of this promoter were confirmed using reporter gene fusions and 5' deletion analysis. The data indicated that regulation of urease expression by nitrogen availability in A. naeslundii may require a positive transcriptional activator. Plaque bacteria may experience nitrogen limitation when carbohydrates are present in excess. Therefore, based on the results of this study and in contrast to previous beliefs, strains of A. naeslundii may have the potential to be significant contributors to total plaque ureolysis, particularly during periods when there is an increased risk for caries development.
Collapse
Affiliation(s)
- E Morou-Bermudez
- Center for Oral Biology and Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
| | | |
Collapse
|
20
|
Bergeron LJ, Morou-Bermudez E, Burne RA. Characterization of the fructosyltransferase gene of Actinomyces naeslundii WVU45. J Bacteriol 2000; 182:3649-54. [PMID: 10850978 PMCID: PMC94534 DOI: 10.1128/jb.182.13.3649-3654.2000] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Oral actinomycetes produce fructosyltransferase (FTF) enzymes which convert sucrose into polymers of D-fructose, known as levans, and these polymers are thought to contribute to the persistence and virulence of the organisms. A gene encoding FTF was isolated from Actinomyces naeslundii WVU45; the deduced amino acid sequence showed significant similarity to known levansucrases of gram-negative environmental isolates but was less similar to FTFs from gram-positive bacteria. A transcriptional start site was mapped by primer extension 70 bp 5' from the putative start codon. Promoter fusions to a chloramphenicol acetyltransferase gene were used to confirm that there was a functional promoter driving ftf expression and to show that sequences located 86 to 218 bp upstream of the transcription initiation site were required for optimal ftf expression. Quantitative slot blot analysis against total RNA from cells grown on different sugars or from different growth phases revealed that ftf was constitutively transcribed. Thus, the A. naeslundii FTF is more similar in primary sequence and the regulation of expression to levansucrases of gram-negative bacteria than gram-positive bacteria.
Collapse
Affiliation(s)
- L J Bergeron
- Center for Oral Biology, Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
| | | | | |
Collapse
|
21
|
Yeung MK. Molecular and genetic analyses of Actinomyces spp. CRITICAL REVIEWS IN ORAL BIOLOGY AND MEDICINE : AN OFFICIAL PUBLICATION OF THE AMERICAN ASSOCIATION OF ORAL BIOLOGISTS 2000; 10:120-38. [PMID: 10759417 DOI: 10.1177/10454411990100020101] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Members of the genus Actinomyces are predominant primary colonizers of the oral cavity and play an important role in initiating plaque development. These bacteria have evolved unique mechanisms that favor colonization and persistence in this micro-environment. The expression of cell-surface fimbriae is correlated with the ability of these bacteria to adhere to specific receptors on the tooth and mucosal surfaces, and to interact with other plaque bacteria. The elaboration of sialidase is thought to enhance fimbriae-mediated adherence by unmasking the fimbrial receptors on mammalian cells. The presence of certain cell-associated or extracellular enzymes, including those involved in sucrose or urea metabolism, may provide the means for these bacteria to thrive under conditions when other growth nutrients are not available. Moreover, these enzyme activities may influence the distribution of other plaque bacteria and promote selection for Actinomyces spp. in certain ecological niches. The recent development of a genetic transfer system for Actinomyces spp. has allowed for studies the results of which demonstrate the existence of multiple genes involved in fimbriae synthesis and function, and facilitated the construction of allelic replacement mutants at each gene locus. Analyses of these mutants have revealed a direct correlation between the synthesis of assembled fimbriae and the observed adherence properties. Further genetic analysis of the various enzyme activities detected from strains of Actinomyces should allow for an assessment of the role of these components in microbial ecology, and their contribution to the overall success of Actinomyces spp. as a primary colonizer and a key player in oral health and disease.
Collapse
Affiliation(s)
- M K Yeung
- Department of Pediatric Dentistry, University of Texas Health Science Center at San Antonio, 78284, USA
| |
Collapse
|
22
|
Morou-Bermudez E, Burne RA. Genetic and physiologic characterization of urease of Actinomyces naeslundii. Infect Immun 1999; 67:504-12. [PMID: 9916052 PMCID: PMC96348 DOI: 10.1128/iai.67.2.504-512.1999] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/1998] [Accepted: 11/04/1998] [Indexed: 11/20/2022] Open
Abstract
Ammonia production from urea by ureolytic oral bacteria is believed to have a significant impact on oral health and the ecological balance of oral microbial populations. In this study we cloned and characterized the urease gene cluster of Actinomyces naeslundii, which is one of the pioneer organisms in the oral cavity and a significant constituent of supragingival and subgingival dental plaque in children and adults. An internal fragment of the ureC gene of A. naeslundii WVU45 was initially amplified by PCR with degenerate primers derived from conserved amino acid sequences of the large catalytic subunit of urease in bacteria and plants. The PCR product was then used as a probe to identify recombinant bacteriophages carrying the A. naeslundii urease gene cluster and roughly 30 kbp of flanking DNA. Nucleotide sequence analysis demonstrated that the gene cluster was comprised of seven contiguously arranged open reading frames with significant homologies at the protein and nucleotide sequence levels to the ureABCEFGD genes from other organisms. By using primer extension, a putative transcription initiation site was mapped at 66 bases 5' to the start codon of ureA. A urease-deficient strain was constructed by insertion of a kanamycin resistance determinant within the ureC gene via allelic replacement. In contrast to the wild-type organism, the isogenic mutant was unable to grow in a semidefined medium supplemented with urea as the nitrogen source and was not protected by the addition of urea against killing in moderately acidic environments. These data indicated that urea can be effectively utilized as a nitrogen source by A. naeslundii via a urease-dependent pathway and that ureolysis can protect A. naeslundii against environmental acidification at physiologically relevant pH values. Therefore, urease could confer to A. naeslundii critical selective advantages over nonureolytic organisms in dental plaque, constituting an important determinant of plaque ecology.
Collapse
Affiliation(s)
- E Morou-Bermudez
- Center for Oral Biology and Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York 14642, USA
| | | |
Collapse
|
23
|
Yeung MK, Donkersloot JA, Cisar JO, Ragsdale PA. Identification of a gene involved in assembly of Actinomyces naeslundii T14V type 2 fimbriae. Infect Immun 1998; 66:1482-91. [PMID: 9529071 PMCID: PMC108078 DOI: 10.1128/iai.66.4.1482-1491.1998] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The nucleotide sequence of the Actinomyces naeslundii T14V type 2 fimbrial structural subunit gene, fimA, and the 3' flanking DNA region was determined. The fimA gene encoded a 535-amino-acid precursor subunit protein (FimA) which included both N-terminal leader and C-terminal cell wall sorting sequences. A second gene, designated orf365, that encoded a 365-amino-acid protein which contained a putative transmembrane segment was identified immediately 3' to fimA. Mutants in which either fimA or orf365 was replaced with a kanamycin resistance gene did not participate in type 2 fimbriae-mediated coaggregation with Streptococcus oralis 34. Type 2 fimbrial antigen was not detected in cell extracts of the fimA mutant by Western blotting with anti-A. naeslundii type 2 fimbrial antibody, but the subunit protein was detected in extracts of the orf365 mutant. The subunit protein detected in this mutant also was immunostained by an antibody raised against a synthetic peptide representing the C-terminal 20 amino acid residues of the predicted FimA. The antipeptide antibody reacted with FimA isolated from the recombinant Escherichia coli clone containing fimA but did not react with purified type 2 fimbriae in extracts of the wild-type strain. These results indicate that synthesis of type 2 fimbriae in A. naeslundii T14V may involve posttranslational cleavage of both the N-terminal and C-terminal peptides of the precursor subunit and also the expression of orf365.
Collapse
Affiliation(s)
- M K Yeung
- Department of Pediatric Dentistry, The University of Texas Health Science Center at San Antonio, 78284, USA.
| | | | | | | |
Collapse
|
24
|
Jost BH, Billington SJ, Songer JG. Electroporation-mediated transformation of Arcanobacterium (Actinomyces) pyogenes. Plasmid 1997; 38:135-40. [PMID: 9339471 DOI: 10.1006/plas.1997.1299] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Plasmids derived from pNG2 or RSF1010 were introduced into strains of Arcanobacterium (Actinomyces) pyogenes by electroporation. Electroporation conditions were varied systematically to give a maximum electroporation frequency of 3.7 x 10(5) CFU/microgram DNA at 1.5 kV/cm and 246 omega, resulting in a time constant of approximately 10 ms. The A. pyogenes transformants expressed plasmid-encoded resistance to chloramphenicol, erythromycin, kanamycin, and streptomycin. The source of incoming DNA affected the growth rate of transformants, but not the electroporation efficiency. This is the first report of genetic transformation of the veterinary pathogen A. pyogenes.
Collapse
Affiliation(s)
- B H Jost
- Department of Veterinary Science and Microbiology, University of Arizona, Tucson 85721, USA.
| | | | | |
Collapse
|
25
|
Yeung MK, Ragsdale PA. Synthesis and function of Actinomyces naeslundii T14V type 1 fimbriae require the expression of additional fimbria-associated genes. Infect Immun 1997; 65:2629-39. [PMID: 9199430 PMCID: PMC175372 DOI: 10.1128/iai.65.7.2629-2639.1997] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The nucleotide sequence of the chromosomal DNA flanking the Actinomyces naeslundii (formerly A. viscosus) T14V type 1 fimbrial structural subunit gene (fimP) was determined. Six open reading frames (ORFs), in the order 5' ORF3, ORF2, ORF1,fimP, ORF4, ORF5, ORF6 3', were identified. ORF1 encoded a protein of 408 amino acid residues (Mr = 39,270) and had significant sequence homology with the A. naeslundii T14V type 1 and A. naeslundii WVU45 type 2 fimbrial structural subunits. An in-frame fusion of ORF1 to the malE gene of the expression vector, pMAL-c2, yielded a protein that was immunostained with antibodies raised against the maltose binding protein and A. naeslundii T14V whole bacteria. Digestion of the fusion protein with factor Xa released a protein (apparent molecular mass of 34 kDa) that was immunostained only with the antibody directed against A. naeslundii T14V whole bacterial cells. Integration plasmids carrying a kanamycin resistance gene (kan) that was used to substitute for ORF1 or for DNA fragments internal to the coding region of the other five ORFs were used to transform A. naeslundii T14V. Neither type 1 fimbriae nor the 65-kDa fimbrial structural subunit was detected in mutants obtained by allelic replacement of ORF1 or ORF2. Mutants obtained by allelic replacement of ORF3 or ORF4 expressed only the 65-kDa fimbrial structural subunit. These mutants did not bind, in vitro, to proline-rich proteins that serve as the receptors for Actinomyces type 1 fimbriae. In contrast, a mutant in which the integration plasmid DNA had been inserted at a site close to the carboxyl terminus of ORF6 expressed type 1 fimbriae and had adherence properties similar to those observed in the wild-type strain. These results demonstrate the existence of additional genes near fimP that are likely to be involved in the synthesis and function of cell surface fimbriae of A. naeslundii T14V.
Collapse
Affiliation(s)
- M K Yeung
- Department of Pediatric Dentistry, The University of Texas Health Science Center at San Antonio, 78284, USA.
| | | |
Collapse
|
26
|
Cisar JO, Takahashi Y, Ruhl S, Donkersloot JA, Sandberg AL. Specific inhibitors of bacterial adhesion: observations from the study of gram-positive bacteria that initiate biofilm formation on the tooth surface. Adv Dent Res 1997; 11:168-75. [PMID: 9524453 DOI: 10.1177/08959374970110010801] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Oral surfaces are bathed in secretory antibodies and other salivary macromolecules that are potential inhibitors of specific microbial adhesion. Indigenous Gram-positive bacteria that colonize teeth, including viridans streptococci and actinomyces, may avoid inhibition of adhesion by host secretory molecules through various strategies that involve the structural design and binding properties of bacterial adhesins and receptors. Further studies to define the interactions of these molecules within the host environment may suggest novel approaches for the control of oral biofilm formation.
Collapse
Affiliation(s)
- J O Cisar
- Laboratory of Microbial Ecology, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland 20892, USA
| | | | | | | | | |
Collapse
|
27
|
Ellen RP, Lépine G, Nghiem PM. In vitro models that support adhesion specificity in biofilms of oral bacteria. Adv Dent Res 1997; 11:33-42. [PMID: 9524440 DOI: 10.1177/08959374970110011401] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Adhesion to adsorbed pellicles and interspecies co-adhesion to form plaque biofilms involve selective interactions of bacterial adhesins with specific receptors. Our laboratory has devised in vitro assays for co-adhesion between Actinomyces naeslundii and Streptococcus oralis or Porphyromonas gingivalis on saliva-coated mineral and hexadecane droplet substrata. P. gingivalis structures significant for co-adhesion with A. naeslundii include surface vesicles and fimbriae. A family of arginine-specific cysteine proteinases in vesicles may be involved in adherence to bacteria, to host cells, and to matrix proteins. New research from several laboratories has found that such proteinases are processed from genes encoding polyproteins containing both proteinase and hemagglutinin domains. In addition to enzyme-substrate recognition, bacterial adhesion is often determined by specific protein-peptide and lectincarbohydrate recognition. A. naeslundii--salivary prolinerich protein, S. gordonii--salivary alpha-amylase, and Treponema denticola--matrix protein recognition are examples of the former. Co-adhesion of A. naeslundii and S. oralis is an example of the latter. Lactose can selectively desorb A. naeslundii cells from mixed biofilms with S. oralis, a demonstration of the significance of specificity. Although non-specific forces are probably secondary to stereochemical fit in determining the selective range of surfaces that bacteria have evolved to recognize and bind, they probably help stabilize non-covalent bonds within aligned, complementary domains.
Collapse
Affiliation(s)
- R P Ellen
- Department of Periodontics, University of Toronto, Faculty of Dentistry, ON, Canada
| | | | | |
Collapse
|
28
|
Yeung MK, Kozelsky CS. Transfection of Actinomyces spp. by genomic DNA of bacteriophages from human dental plaque. Plasmid 1997; 37:141-53. [PMID: 9169205 DOI: 10.1006/plas.1997.1285] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Bacteriophages that produced turbid or clear zones of lysis in strains of Actinomyces were isolated from 22 of 124 samples of fresh human dental plaque. All human and nonhuman strains of Actinomyces viscosus or Actinomyces naeslundii tested in this study were sensitive to infection by one or more of these phages. In contrast, none of the Actinomyces odontolyticus, Actinomyces israelii, or Actinomyces bovis strains tested were susceptible. Results of restriction endonuclease analyses indicated that the genomes of these phages consisted of double-stranded DNA molecules ranging in size between 16 and 60 kbp. Sequence homology under hybridization conditions of high stringency was observed among a few of the isolated phages. A lysogenized isolate of A. viscosus MG-1 was obtained following infection with a temperate phage, designated phi 225. Results of Southern blot analyses indicated that phi 225 replicated as a plasmid in the lysogenized strain. Genomic DNA from several lytic phages was used to establish conditions for transfection by electroporation of strains of Actinomyces spp. Efficiencies of DNA transfer ranged from 10(2) to 10(5) plaque-forming units per microgram of DNA were obtained under optimal transfection conditions. The results of these studies demonstrate that transfer of genetic information in Actinomyces spp. can be achieved by transfection.
Collapse
Affiliation(s)
- M K Yeung
- Department of Pediatric Dentistry, University of Texas Health Science Center at San Antonio 78284-7888, USA.
| | | |
Collapse
|
29
|
Abstract
Adherence to a surface is a key element for colonization of the human oral cavity by the more than 500 bacterial taxa recorded from oral samples. Three surfaces are available: teeth, epithelial mucosa, and the nascent surface created as each new bacterial cell binds to existing dental plaque. Oral bacteria exhibit specificity for their respective colonization sites. Such specificity is directed by adhesin-receptor cognate pairs on genetically distinct cells. Colonization is successful when adherent cells grow and metabolically participate in the oral bacterial community. The potential roles of adherence-relevant molecules are discussed in the context of the dynamic nature of the oral econiche.
Collapse
Affiliation(s)
- C J Whittaker
- Laboratory of Microbial Ecology, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland 20892, USA
| | | | | |
Collapse
|
30
|
|
31
|
Yeung MK. Construction and use of integration plasmids to generate site-specific mutations in the Actinomyces viscosus T14V chromosome. Infect Immun 1995; 63:2924-30. [PMID: 7622214 PMCID: PMC173398 DOI: 10.1128/iai.63.8.2924-2930.1995] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Stable transformants of Actinomyces viscosus T14V carrying heterologous DNA were obtained with the aid of integration plasmids. These plasmids contained a kanamycin resistance (Kmr) gene flanked by A. viscosus T14V genomic DNA, including parts of the type 1 structural fimbrial subunit gene (fimP) on one or both sides of the antibiotic marker. Significantly more Kmr transformants were obtained with a plasmid carrying longer segments of homologous strain T14V DNA. Integration of this plasmid into the A. viscosus T14V genome affected the expression and function of type 1 fimbriae in the transformants. In the transformant strain designated A. viscosus MY50D, the inactivated fimP replaced the wild-type fimP via allelic replacement. A. viscosus MY51S and MY52S each contained a copy of the plasmid integrated into the genome by a Campbell-like insertion mechanism. A. viscosus MY50D and MY51S lacked type 1 fimbriae and did not bind to proline-rich proteins (the fimbrial receptors) immobilized on nitrocellulose. In contrast, strain MY52S synthesized the structural subunit protein, as detected by immunostaining with anti-A. viscosus T14V type 1 fimbria antibodies. However, the high-molecular-weight proteins observed in sodium dodecyl sulfate-polyacrylamide gels of fimbriae from the cell wall of the wild-type strain T14V were absent in cell wall preparations of this strain. Moreover, A. viscosus MY52S failed to bind, in vitro, to proline-rich proteins. Thus, these results demonstrate that insertion of heterologous DNA at specific sites of the Actinomyces genome can be facilitated with integratable plasmids and that the transformants and mutants generated will aid in the delineation of the roles and contributions of specific genes to the structure and function of any macromolecule produced by these organisms.
Collapse
Affiliation(s)
- M K Yeung
- Department of Pediatric Dentistry, University of Texas Health Science Center, San Antonio 78284-7888, USA
| |
Collapse
|