Involvement of the Histone-Like Nucleoid Structuring Protein (H-NS) in <i>Acinetobacter baumannii’s</i> Natural Transformation
Casin Le,
Camila Pimentel,
Marisel R. Tuttobene,
Tomás Subils,
Jenny Escalante,
Brent Nishimura,
Susana Arriaga,
Deja Rodgers,
Robert A. Bonomo,
Rodrigo Sieira,
Marcelo E. Tolmasky,
María Soledad Ramírez
Affiliations
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
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
Marisel R. Tuttobene
Área Biología Molecular, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, 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
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
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
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
Robert A. Bonomo
Research Service and GRECC, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, 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
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
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.