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Wang L, Liu P, Wu Y, Pei H, Cao X. Inhibitory effect of Lonicera japonica flos on Streptococcus mutans biofilm and mechanism exploration through metabolomic and transcriptomic analyses. Front Microbiol 2024; 15:1435503. [PMID: 39027105 PMCID: PMC11256199 DOI: 10.3389/fmicb.2024.1435503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2024] [Accepted: 06/05/2024] [Indexed: 07/20/2024] Open
Abstract
Introduction Streptococcus mutans was the primary pathogenic organism responsible for dental caries. Lonicera japonica flos (LJF) is a traditional herb in Asia and Europe and consumed as a tea beverage for thousands of years. Methods The inhibitory effect and mechanism of LJF on biofilm formation by S. mutans was investigated. The active extracts of LJF were validated for their inhibitory activity by examining changes in surface properties such as adherence, hydrophobicity, auto-aggregation abilities, and exopolysaccharides (EPS) production, including water-soluble glucan and water-insoluble glucan. Results and discussion LJF primarily inhibited biofilm formation through the reduction of EPS production, resulting in alterations in cell surface characteristics and growth retardation in biofilm formation cycles. Integrated transcriptomic and untargeted metabolomics analyses revealed that EPS production was modulated through two-component systems (TCS), quorum sensing (QS), and phosphotransferase system (PTS) pathways under LJF stress conditions. The sensing histidine kinase VicK was identified as an important target protein, as LJF caused its dysregulated expression and blocked the sensing of autoinducer II (AI-2). This led to the inhibition of response regulator transcriptional factors, down-regulated glycosyltransferase (Gtf) activity, and decreased production of water-insoluble glucans (WIG) and water-soluble glucans (WSG). This is the first exploration of the inhibitory effect and mechanism of LJF on S. mutans, providing a theoretical basis for the application of LJF in functional food, oral health care, and related areas.
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Affiliation(s)
| | | | | | | | - Xueli Cao
- Beijing Technology and Business University, Beijing Advanced Innovation Centre for Food Nutrition and Human Health, Beijing, China
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2
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Willner DL, Paudel S, Halleran AD, Solini GE, Gray V, Saha MS. Transcriptional dynamics during Rhodococcus erythropolis infection with phage WC1. BMC Microbiol 2024; 24:107. [PMID: 38561651 PMCID: PMC10986025 DOI: 10.1186/s12866-024-03241-4] [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: 11/25/2023] [Accepted: 02/27/2024] [Indexed: 04/04/2024] Open
Abstract
BACKGROUND Belonging to the Actinobacteria phylum, members of the Rhodococcus genus thrive in soil, water, and even intracellularly. While most species are non-pathogenic, several cause respiratory disease in animals and, more rarely, in humans. Over 100 phages that infect Rhodococcus species have been isolated but despite their importance for Rhodococcus ecology and biotechnology applications, little is known regarding the molecular genetic interactions between phage and host during infection. To address this need, we report RNA-Seq analysis of a novel Rhodococcus erythopolis phage, WC1, analyzing both the phage and host transcriptome at various stages throughout the infection process. RESULTS By five minutes post-infection WC1 showed upregulation of a CAS-4 family exonuclease, putative immunity repressor, an anti-restriction protein, while the host showed strong upregulation of DNA replication, SOS repair, and ribosomal protein genes. By 30 min post-infection, WC1 DNA synthesis genes were strongly upregulated while the host showed increased expression of transcriptional and translational machinery and downregulation of genes involved in carbon, energy, and lipid metabolism pathways. By 60 min WC1 strongly upregulated structural genes while the host showed a dramatic disruption of metal ion homeostasis. There was significant expression of both host and phage non-coding genes at all time points. While host gene expression declined over the course of infection, our results indicate that phage may exert more selective control, preserving the host's regulatory mechanisms to create an environment conducive for virion production. CONCLUSIONS The Rhodococcus genus is well recognized for its ability to synthesize valuable compounds, particularly steroids, as well as its capacity to degrade a wide range of harmful environmental pollutants. A detailed understanding of these phage-host interactions and gene expression is not only essential for understanding the ecology of this important genus, but will also facilitate development of phage-mediated strategies for bioremediation as well as biocontrol in industrial processes and biomedical applications. Given the current lack of detailed global gene expression studies on any Rhodococcus species, our study addresses a pressing need to identify tools and genes, such as F6 and rpf, that can enhance the capacity of Rhodococcus species for bioremediation, biosynthesis and pathogen control.
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Affiliation(s)
- Dana L Willner
- Data Science Program, William & Mary, Williamsburg, VA, USA
| | - Sudip Paudel
- Department of Biology, William & Mary, Williamsburg, VA, USA
- Wyss Institute, Harvard University, Cambridge, MA, USA
| | - Andrew D Halleran
- Department of Biology, William & Mary, Williamsburg, VA, USA
- Atalaya Capital Management, New York, NY, USA
| | - Grace E Solini
- Department of Biology, William & Mary, Williamsburg, VA, USA
- California Institute of Technology, Pasadena, CA, USA
| | - Veronica Gray
- Department of Biology, William & Mary, Williamsburg, VA, USA
- Georgetown University School of Medicine, Washington, DC, USA
| | - Margaret S Saha
- Department of Biology, William & Mary, Williamsburg, VA, USA.
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3
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Rimal B, Senzani S, Ealand C, Lamichhane G, Kana B, Kim SJ. Peptidoglycan compositional analysis of Mycobacterium smegmatis using high-resolution LC-MS. Sci Rep 2022; 12:11061. [PMID: 35773428 PMCID: PMC9247062 DOI: 10.1038/s41598-022-15324-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 06/22/2022] [Indexed: 11/21/2022] Open
Abstract
Peptidoglycan (PG) is the exoskeleton of bacterial cells and is required for their viability, growth, and cell division. Unlike most bacteria, mycobacteria possess an atypical PG characterized by a high degree of unique linkages and chemical modifications which most likely serve as important determinants of virulence and pathogenesis in mycobacterial diseases. Despite this important role, the chemical composition and molecular architecture of mycobacterial PG have yet to be fully determined. Here we determined the chemical composition of PG from Mycobacterium smegmatis using high-resolution liquid chromatography-mass spectrometry. Purified cell walls from the stationary phase were digested with mutanolysin and compositional analysis was performed on 130 muropeptide ions that were identified using an in silico PG library. The relative abundance for each muropeptide ion was measured by integrating the extracted-ion chromatogram. The percentage of crosslink per PG subunit was measured at 45%. While both 3→3 and 4→3 transpeptide cross-linkages were found in PG dimers, a high abundance of 3→3 linkages was found associated with the trimers. Approximately 43% of disaccharides in the PG of M. smegmatis showed modifications by acetylation or deacetylation. A significant number of PG trimers are found with a loss of 41.00 amu that is consistent with N-deacetylation, whereas the dimers show a gain of 42.01 amu corresponding to O-acetylation of the PG disaccharides. This suggests a possible role of PG acetylation in the regulation of cell wall homeostasis in M. smegmatis. Collectively, these data report important novel insights into the ultrastructure of mycobacterial PG.
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Affiliation(s)
- Binayak Rimal
- Institute of Biomedical Studies, Baylor University, Waco, TX, 76798, USA.,Division of Infectious Diseases, School of Medicine, Johns Hopkins University, Baltimore, MD, 21287, USA
| | - Sibusiso Senzani
- National Health Laboratory Service, Faculty of Health Sciences, DST/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, University of the Witwatersrand, Johannesburg, 2001, South Africa
| | - Christopher Ealand
- National Health Laboratory Service, Faculty of Health Sciences, DST/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, University of the Witwatersrand, Johannesburg, 2001, South Africa
| | - Gyanu Lamichhane
- Division of Infectious Diseases, School of Medicine, Johns Hopkins University, Baltimore, MD, 21287, USA
| | - Bavesh Kana
- National Health Laboratory Service, Faculty of Health Sciences, DST/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, University of the Witwatersrand, Johannesburg, 2001, South Africa.
| | - Sung Joon Kim
- Department of Chemistry, Howard University, Chemistry Building, 525 College Street, Washington, DC, 20059, USA.
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Papadopoulos AO, Ealand C, Gordhan BG, VanNieuwenhze M, Kana BD. Characterisation of a putative M23-domain containing protein in Mycobacterium tuberculosis. PLoS One 2021; 16:e0259181. [PMID: 34784363 PMCID: PMC8594824 DOI: 10.1371/journal.pone.0259181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Accepted: 10/14/2021] [Indexed: 12/01/2022] Open
Abstract
Mycobacterium tuberculosis, the causative agent of tuberculosis remains a global health concern, further compounded by the high rates of HIV-TB co-infection and emergence of multi- and extensive drug resistant TB, all of which have hampered efforts to eradicate this disease. As a result, novel anti-tubercular interventions are urgently required, with the peptidoglycan component of the M. tuberculosis cell wall emerging as an attractive drug target. Peptidoglycan M23 endopeptidases can function as active cell wall hydrolases or degenerate activators of hydrolases in a variety of bacteria, contributing to important processes such as bacterial growth, division and virulence. Herein, we investigate the function of the Rv0950-encoded putative M23 endopeptidase in M. tuberculosis. In silico analysis revealed that this protein is conserved in mycobacteria, with a zinc-binding catalytic site predictive of hydrolytic activity. Transcript analysis indicated that expression of Rv0950c was elevated during lag and log phases of growth and reduced in stationary phase. Deletion of Rv0950c yielded no defects in growth, colony morphology, antibiotic susceptibility or intracellular survival but caused a reduction in cell length. Staining with a monopeptide-derived fluorescent D-amino acid, which spatially reports on sites of active PG biosynthesis or repair, revealed an overall reduction in uptake of the probe in ΔRv0950c. When stained with a dipeptide probe in the presence of cell wall damaging agents, the ΔRv0950c mutant displayed reduced sidewall labelling. As bacterial peptidoglycan metabolism is important for survival and pathogenesis, the role of Rv0950c and other putative M23 endopeptidases in M. tuberculosis should be explored further.
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Affiliation(s)
- Andrea Olga Papadopoulos
- Faculty of Health Sciences, DSI/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, University of the Witwatersrand, National Health Laboratory Service, Johannesburg, South Africa
| | - Christopher Ealand
- Faculty of Health Sciences, DSI/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, University of the Witwatersrand, National Health Laboratory Service, Johannesburg, South Africa
| | - Bhavna Gowan Gordhan
- Faculty of Health Sciences, DSI/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, University of the Witwatersrand, National Health Laboratory Service, Johannesburg, South Africa
| | - Michael VanNieuwenhze
- Department of Chemistry, Indiana University Bloomington, Bloomington, Indiana, United States of America
| | - Bavesh Davandra Kana
- Faculty of Health Sciences, DSI/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, University of the Witwatersrand, National Health Laboratory Service, Johannesburg, South Africa
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5
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Rifamycin antibiotics and the mechanisms of their failure. J Antibiot (Tokyo) 2021; 74:786-798. [PMID: 34400805 DOI: 10.1038/s41429-021-00462-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 07/21/2021] [Accepted: 07/26/2021] [Indexed: 02/07/2023]
Abstract
Rifamycins are a class of antibiotics that were first discovered in 1957 and are known for their use in treating tuberculosis (TB). Rifamycins exhibit bactericidal activity against many Gram-positive and Gram-negative bacteria by inhibiting RNA polymerase (RNAP); however, resistance is prevalent and the mechanisms range from primary target modification and antibiotic inactivation to cytoplasmic exclusion. Further, phenotypic resistance, in which only a subpopulation of bacteria grow in concentrations exceeding their minimum inhibitory concentration, and tolerance, which is characterized by reduced rates of bacterial cell death, have been identified as additional causes of rifamycin failure. Here we summarize current understanding and recent developments regarding this critical antibiotic class.
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Grigorov A, Bychenko O, Salina EG, Skvortsova Y, Mazurova A, Skvortsov T, Kaprelyants A, Azhikina T. Small RNA F6 Provides Mycobacterium smegmatis Entry into Dormancy. Int J Mol Sci 2021; 22:11536. [PMID: 34768965 PMCID: PMC8583896 DOI: 10.3390/ijms222111536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 10/21/2021] [Accepted: 10/22/2021] [Indexed: 11/16/2022] Open
Abstract
Regulatory small non-coding RNAs play a significant role in bacterial adaptation to changing environmental conditions. Various stresses such as hypoxia and nutrient starvation cause a reduction in the metabolic activity of Mycobacterium smegmatis, leading to entry into dormancy. We investigated the functional role of F6, a small RNA of M. smegmatis, and constructed an F6 deletion strain of M. smegmatis. Using the RNA-seq approach, we demonstrated that gene expression changes that accompany F6 deletion contributed to bacterial resistance against oxidative stress. We also found that F6 directly interacted with 5'-UTR of MSMEG_4640 mRNA encoding RpfE2, a resuscitation-promoting factor, which led to the downregulation of RpfE2 expression. The F6 deletion strain was characterized by the reduced ability to enter into dormancy (non-culturability) in the potassium deficiency model compared to the wild-type strain, indicating that F6 significantly contributes to bacterial adaptation to non-optimal growth conditions.
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Affiliation(s)
- Artem Grigorov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia; (A.G.); (O.B.); (Y.S.); (A.M.)
| | - Oksana Bychenko
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia; (A.G.); (O.B.); (Y.S.); (A.M.)
| | - Elena G. Salina
- Research Center of Biotechnology, Bach Institute of Biochemistry, 119071 Moscow, Russia; (E.G.S.); (A.K.)
| | - Yulia Skvortsova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia; (A.G.); (O.B.); (Y.S.); (A.M.)
| | - Arina Mazurova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia; (A.G.); (O.B.); (Y.S.); (A.M.)
| | - Timofey Skvortsov
- School of Pharmacy, Queen’s University Belfast, Belfast BT9 7BL, UK;
| | - Arseny Kaprelyants
- Research Center of Biotechnology, Bach Institute of Biochemistry, 119071 Moscow, Russia; (E.G.S.); (A.K.)
| | - Tatyana Azhikina
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia; (A.G.); (O.B.); (Y.S.); (A.M.)
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McIvor A, Gordhan BG, Waja Z, Otwombe K, Martinson NA, Kana BD. Supplementation of sputum cultures with culture filtrate to detect tuberculosis in a cross-sectional study of HIV-infected individuals. Tuberculosis (Edinb) 2021; 129:102103. [PMID: 34144375 DOI: 10.1016/j.tube.2021.102103] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Revised: 03/02/2021] [Accepted: 06/09/2021] [Indexed: 10/21/2022]
Abstract
While some healthcare systems have shifted to molecular diagnostics, culture still remains the gold standard for tuberculosis diagnosis, but it is limited by its long duration to a positive result. Methods to reduce time to culture positivity (TTP) are urgently required. We determined if growth factor supplementation in the mycobacterial growth indicator tube (MGIT) culture system reduces TTP. MGITs were supplemented with fresh culture filtrate (CF) as a source of growth stimulatory molecules from axenic Mycobacterium tuberculosis culture. Different volumes of CF and media components were tested. The performance of these modified MGITs was assessed with sputum from HIV-TB co-infected individuals. Reducing the volume of MGIT cultures and removal of detergent from cultures grown to generate CF had a marginal but significant benefit on reducing TTP. In a subset of specimens, CF inhibited growth. Following optimization of methods, a reduced TTP occurred in specimens with low bacillary load as measured by GeneXpert, smear microscopy and colony forming units. Three specimens that were negative under standard conditions flagged positive following CF supplementation. Our data provide preliminary evidence that addition of CF to MGIT cultures can enhance detection of M. tuberculosis in HIV-TB co-infected patients with low sputum bacillary loads.
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Affiliation(s)
- Amanda McIvor
- DST/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the National Health Laboratory Service, South Africa
| | - Bhavna Gowan Gordhan
- DST/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the National Health Laboratory Service, South Africa
| | - Ziyaad Waja
- Perinatal HIV Research Unit (PHRU), University of the Witwatersrand, Johannesburg, South Africa
| | - Kennedy Otwombe
- Perinatal HIV Research Unit (PHRU), University of the Witwatersrand, Johannesburg, South Africa; School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, South Africa
| | - Neil A Martinson
- DST/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the National Health Laboratory Service, South Africa; Perinatal HIV Research Unit (PHRU), University of the Witwatersrand, Johannesburg, South Africa; John Hopkins University, Centre for Tuberculosis Research, Baltimore, MD, USA
| | - Bavesh Davandra Kana
- DST/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the National Health Laboratory Service, South Africa; CAPRISA, Centre for the AIDS Programme of Research in South Africa, Durban, South Africa.
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8
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Gordhan BG, Peters JS, McIvor A, Machowski EE, Ealand C, Waja Z, Martinson N, Kana BD. Detection of differentially culturable tubercle bacteria in sputum using mycobacterial culture filtrates. Sci Rep 2021; 11:6493. [PMID: 33753820 PMCID: PMC7985135 DOI: 10.1038/s41598-021-86054-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 03/01/2021] [Indexed: 11/22/2022] Open
Abstract
Rapid detection of tuberculosis (TB) infection is paramount to curb further transmission. The gold standard for this remains mycobacterial culture, however emerging evidence confirms the presence of differentially culturable tubercle bacteria (DCTB) in clinical specimens. These bacteria do not grow under standard culture conditions and require the presence of culture filtrate (CF), from axenic cultures of Mycobacterium tuberculosis (Mtb), to emerge. It has been hypothesized that molecules such as resuscitation promoting factors (Rpfs), fatty acids and cyclic-AMP (cAMP) present in CF are responsible for the growth stimulatory activity. Herein, we tested the ability of CF from the non-pathogenic bacterium Mycobacterium smegmatis (Msm) to stimulate the growth of DCTB, as this organism provides a more tractable source of CF. We also interrogated the role of Mtb Rpfs in stimulation of DCTB by creating recombinant strains of Msm that express Mtb rpf genes in various combinations. CF derived from this panel of strains was tested on sputum from individuals with drug susceptible TB prior to treatment. CF from wild type Msm did not enable detection of DCTB in a manner akin to Mtb CF preparations and whilst the addition of RpfABMtb and RpfABCDEMtb to an Msm mutant devoid of its native rpfs did improve detection of DCTB compared to the no CF control, it was not statistically different to the empty vector control. To further investigate the role of Rpfs, we compared the growth stimulatory activity of CF from Mtb, with and without Rpfs and found these to be equivalent. Next, we tested chemically diverse fatty acids and cAMP for growth stimulation and whilst some selective stimulatory effect was observed, this was not significantly higher than the media control and not comparable to CF. Together, these data indicate that the growth stimulatory effect observed with Mtb CF is most likely the result of a combination of factors. Future work aimed at identifying the nature of these growth stimulatory molecules may facilitate improvement of culture-based diagnostics for TB.
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Affiliation(s)
- Bhavna G Gordhan
- Department of Science and Technology/National Research Foundation Centre of Excellence for Biomedical TB Research, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the National Health Laboratory Service, P. O. Box 1038, Johannesburg, 2000, South Africa
| | - Julian S Peters
- Department of Science and Technology/National Research Foundation Centre of Excellence for Biomedical TB Research, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the National Health Laboratory Service, P. O. Box 1038, Johannesburg, 2000, South Africa
| | - Amanda McIvor
- Department of Science and Technology/National Research Foundation Centre of Excellence for Biomedical TB Research, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the National Health Laboratory Service, P. O. Box 1038, Johannesburg, 2000, South Africa
| | - Edith E Machowski
- Department of Science and Technology/National Research Foundation Centre of Excellence for Biomedical TB Research, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the National Health Laboratory Service, P. O. Box 1038, Johannesburg, 2000, South Africa
| | - Christopher Ealand
- Department of Science and Technology/National Research Foundation Centre of Excellence for Biomedical TB Research, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the National Health Laboratory Service, P. O. Box 1038, Johannesburg, 2000, South Africa
| | - Ziyaad Waja
- Perinatal HIV Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Neil Martinson
- Department of Science and Technology/National Research Foundation Centre of Excellence for Biomedical TB Research, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the National Health Laboratory Service, P. O. Box 1038, Johannesburg, 2000, South Africa.,Perinatal HIV Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.,Center for Tuberculosis Research, Johns Hopkins University, Baltimore, MD, USA
| | - Bavesh D Kana
- Department of Science and Technology/National Research Foundation Centre of Excellence for Biomedical TB Research, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the National Health Laboratory Service, P. O. Box 1038, Johannesburg, 2000, South Africa.
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Hegde SR. Computational Identification of the Proteins Associated With Quorum Sensing and Biofilm Formation in Mycobacterium tuberculosis. Front Microbiol 2020; 10:3011. [PMID: 32038515 PMCID: PMC6988586 DOI: 10.3389/fmicb.2019.03011] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 12/16/2019] [Indexed: 12/23/2022] Open
Abstract
With prolonged therapy and increased instances of drug resistance, tuberculosis is viewed as a serious infectious disease causing high mortality. Emerging concepts in Mycobacterium tuberculosis pathogenicity include biofilm formation, which endows bacterial survival in the host for a long time. To tackle chronic tuberculosis infection, a detailed understanding of the bacterial survival mechanisms is crucial. Using comparative genomics and literature mining, 115 M. tuberculosis proteins were shortlisted for their likely association with biofilm formation or quorum sensing. These include essential genes such as secA2, lpqY-sugABC, Rv1176c, and Rv0195, many of which are also known virulence factors. Furthermore, the functional relationship among these proteins was established by considering known protein-protein interactions, regulatory interactions, and gene expression correlation data/information. Graph centrality and motif analyses predicted the importance of proteins, such as Rv0081, DevR, RegX3, Rv0097, and Rv1996 in M. tuberculosis biofilm formation. Analysis of conservation across other biofilm-forming bacteria suggests that most of these genes are conserved in mycobacteria. As the processes, such as quorum sensing, leading to biofilm formation involve diverse pathways and interactions between proteins, these system-wide studies provide a novel perspective toward understanding mycobacterial persistence.
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Affiliation(s)
- Shubhada R Hegde
- Institute of Bioinformatics and Applied Biotechnology, Bengaluru, India
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10
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Abstract
Actinobacteria is a group of diverse bacteria. Most species in this class of bacteria are filamentous aerobes found in soil, including the genus Streptomyces perhaps best known for their fascinating capabilities of producing antibiotics. These bacteria typically have a Gram-positive cell envelope, comprised of a plasma membrane and a thick peptidoglycan layer. However, there is a notable exception of the Corynebacteriales order, which has evolved a unique type of outer membrane likely as a consequence of convergent evolution. In this chapter, we will focus on the unique cell envelope of this order. This cell envelope features the peptidoglycan layer that is covalently modified by an additional layer of arabinogalactan . Furthermore, the arabinogalactan layer provides the platform for the covalent attachment of mycolic acids , some of the longest natural fatty acids that can contain ~100 carbon atoms per molecule. Mycolic acids are thought to be the main component of the outer membrane, which is composed of many additional lipids including trehalose dimycolate, also known as the cord factor. Importantly, a subset of bacteria in the Corynebacteriales order are pathogens of human and domestic animals, including Mycobacterium tuberculosis. The surface coat of these pathogens are the first point of contact with the host immune system, and we now know a number of host receptors specific to molecular patterns exposed on the pathogen's surface, highlighting the importance of understanding how the cell envelope of Actinobacteria is structured and constructed. This chapter describes the main structural and biosynthetic features of major components found in the actinobacterial cell envelopes and highlights the key differences between them.
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Affiliation(s)
- Kathryn C Rahlwes
- Department of Microbiology, University of Massachusetts, 639 North Pleasant Street, Amherst, MA, 01003, USA
| | - Ian L Sparks
- Department of Microbiology, University of Massachusetts, 639 North Pleasant Street, Amherst, MA, 01003, USA
| | - Yasu S Morita
- Department of Microbiology, University of Massachusetts, 639 North Pleasant Street, Amherst, MA, 01003, USA.
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