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Le C, Pimentel C, Tuttobene MR, Subils T, Escalante J, Nishimura B, Arriaga S, Rodgers D, Bonomo RA, Sieira R, Tolmasky ME, Ramírez MS. Involvement of the Histone-Like Nucleoid Structuring Protein (H-NS) in Acinetobacter baumannii's Natural Transformation. Pathogens 2021; 10:1083. [PMID: 34578115 PMCID: PMC8470039 DOI: 10.3390/pathogens10091083] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 08/22/2021] [Accepted: 08/24/2021] [Indexed: 11/17/2022] Open
Abstract
Most Acinetobacter baumannii strains are naturally competent. Although some information is available about factors that enhance or reduce the frequency of the transformation of this bacterium, the regulatory elements and mechanisms are barely understood. In this article, we describe studies on the role of the histone-like nucleoid structuring protein, H-NS, in the regulation of the expression of genes related to natural competency and the ability to uptake foreign DNA. The expression levels of the natural transformation-related genes pilA, pilT, pilQ, comEA, comEC, comF, and drpA significantly increased in a Δhns derivative of A. baumannii A118. The complementation of the mutant with a recombinant plasmid harboring hns restored the expression levels of six of these genes (pilT remained expressed at high levels) to those of the wild-type strain. The transformation frequency of the A. baumannii A118 Δhns strain was significantly higher than that of the wild-type. Similar, albeit not identical, there were consequences when hns was deleted from the hypervirulent A. baumannii AB5075 strain. In the AB5075 complemented strain, the reduction in gene expression in a few cases was not so pronounced that it reached wild-type levels, and the expression of comEA was enhanced further. In conclusion, the expression of all seven transformation-related genes was enhanced after deleting hns in A. baumannii A118 and AB5075, and these modifications were accompanied by an increase in the cells' transformability. The results highlight a role of H-NS in A. baumannii's natural competence.
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Affiliation(s)
- Casin Le
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831-3599, USA; (C.L.); (C.P.); (J.E.); (B.N.); (S.A.); (D.R.); (M.E.T.)
| | - Camila Pimentel
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831-3599, USA; (C.L.); (C.P.); (J.E.); (B.N.); (S.A.); (D.R.); (M.E.T.)
| | - Marisel R. Tuttobene
- Área Biología Molecular, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario S2002LRK, Argentina;
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), Rosario S2002LRK, Argentina
| | - Tomás Subils
- Instituto de Procesos Biotecnológicos y Químicos de Rosario (IPROBYQ, CONICET-UNR), Rosario S2002LRK, Argentina;
| | - Jenny Escalante
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831-3599, USA; (C.L.); (C.P.); (J.E.); (B.N.); (S.A.); (D.R.); (M.E.T.)
| | - Brent Nishimura
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831-3599, USA; (C.L.); (C.P.); (J.E.); (B.N.); (S.A.); (D.R.); (M.E.T.)
| | - Susana Arriaga
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831-3599, USA; (C.L.); (C.P.); (J.E.); (B.N.); (S.A.); (D.R.); (M.E.T.)
| | - Deja Rodgers
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831-3599, USA; (C.L.); (C.P.); (J.E.); (B.N.); (S.A.); (D.R.); (M.E.T.)
| | - Robert A. Bonomo
- Research Service and GRECC, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH 44106, USA;
- Departments of Medicine, Pharmacology, Molecular Biology and Microbiology, Biochemistry, Proteomics and Bioinformatics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
- CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES), Cleveland, OH 44106, USA
| | - Rodrigo Sieira
- Fundación Instituto Leloir—IIBBA CONICET, Buenos Aires C1405BWE, Argentina;
| | - Marcelo E. Tolmasky
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831-3599, USA; (C.L.); (C.P.); (J.E.); (B.N.); (S.A.); (D.R.); (M.E.T.)
| | - María Soledad Ramírez
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831-3599, USA; (C.L.); (C.P.); (J.E.); (B.N.); (S.A.); (D.R.); (M.E.T.)
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Abstract
Background The origin of cancer cells is the most fundamental yet unresolved problem in cancer research. Cancer cells are thought to be transformed from the normal cells. However, recent studies reveal that the primary cancer cells (PCCs) for cancer initiation and secondary cancer cells (SCCs) for cancer progression are formed in but not transformed from the senescent normal and cancer cells, respectively. Nevertheless, the cellular mechanism of PCCs/SCCs formation is unclear. Here, based on the evidences (1) the nascent PCCs/SCCs are small and organelle-less resembling bacteria; (2) our finding that the cyanobacterium TDX16 acquires its algal host DNA and turns into a new alga TDX16-DE by de novo organelle biogenesis, and (3) PCCs/SCCs formations share striking similarities with TDX16 development and transition, we propose the bacterial origin of cancer cells (BOCC). Presentation of the hypothesis The intracellular bacteria take up the DNAs of the senescent/necrotic normal cells/PCCs and then develop into PCCs/SCCs by hybridizing the acquired DNAs with their own ones and expressing the hybrid genomes. Testing the hypothesis BOCC can be confirmed by testing BOCC-based predictions, such as normal cells with no intracellular bacteria can not "transform" into cancer cells in any conditions. Implications of the hypothesis According to BOCC theory: (1) cancer cells are new single-celled eukaryotes, which is why the hallmarks of cancer are mostly the characteristics of protists; (2) genetic changes and instabilities are not the causes, but the consequences of cancer cell formation; and (3) the common role of carcinogens, infectious agents and relating factors is inducing or related to cellular senescence rather than mutations. Therefore, BOCC theory provides new rationale and direction for cancer research, prevention and therapy.
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Affiliation(s)
- Qing-Lin Dong
- Department of Bioengineering, Hebei University of Technology, Tianjin, 300130 China
| | - Xiang-Ying Xing
- Department of Bioengineering, Hebei University of Technology, Tianjin, 300130 China
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