Bacterial symbionts in oral niche use type VI secretion nanomachinery for fitness increase against pathobionts

Jan Oscarsson; Kai Bao; Akiko Shiratsuchi; Jonas Grossmann; Witold Wolski; Kyaw Min Aung; Mark Lindholm; Anders Johansson; Ferdousi Rahman Mowsumi; Sun Nyunt Wai; Georgios N Belibasakis; Nagihan Bostanci

doi:10.1016/j.isci.2024.109650

Bacterial symbionts in oral niche use type VI secretion nanomachinery for fitness increase against pathobionts

iScience. 2024 Mar 29;27(5):109650. doi: 10.1016/j.isci.2024.109650. eCollection 2024 May 17.

Authors

Affiliations

¹ Oral Microbiology, Department of Odontology, Umeå University, Umeå, Sweden.
² Division of Oral Health and Periodontology, Department of Dental Medicine, Karolinska Institutet, Alfred Nobels Allé 8, 14104 Huddinge, Stockholm, Sweden.
³ Department of Liberal Arts and Sciences, Graduate School of Medicine, Sapporo Medical University, Sapporo, Hokkaido 060-8556, Japan.
⁴ Functional Genomics Center Zurich, ETH Zürich and University of Zürich, Zürich, Switzerland.
⁵ Swiss Institute of Bioinformatics (SIB) Quartier Sorge-Batiment Amphipole, 1015 Lausanne, Switzerland.
⁶ Department of Molecular Biology and the Umeå Centre for Microbial Research (UCMR), and the Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, 90187 Umeå, Sweden.

Abstract

Microbial ecosystems experience spatial and nutrient restrictions leading to the coevolution of cooperation and competition among cohabiting species. To increase their fitness for survival, bacteria exploit machinery to antagonizing rival species upon close contact. As such, the bacterial type VI secretion system (T6SS) nanomachinery, typically expressed by pathobionts, can transport proteins directly into eukaryotic or prokaryotic cells, consequently killing cohabiting competitors. Here, we demonstrate for the first time that oral symbiont Aggregatibacter aphrophilus possesses a T6SS and can eliminate its close relative oral pathobiont Aggregatibacter actinomycetemcomitans using its T6SS. These findings bring nearer the anti-bacterial prospects of symbionts against cohabiting pathobionts while introducing the presence of an active T6SS in the oral cavity.

Keywords: Bacteriology; Microbial flora; Microbial interactions.