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Quorum Sensing Controls the CRISPR and Type VI Secretion Systems in Aliivibrio wodanis 06/09/139
Amudha Deepalakshmi Maharajan1, Erik Hjerde1,2, Hilde Hansen1
1Norwegian Structural Biology Center and Department of Chemistry, Faculty of Science and Technology, UiT The Arctic University of Norway, Tromsø, Norway.
Frontiers in Veterinary Science
|February 25, 2022
Summary
Bacterial survival strategies like Type VI Secretion Systems (T6SSs) and CRISPR are regulated by quorum sensing (QS) in Aliivibrio wodanis. This study reveals QS dependence of T6SSs and CRISPR, crucial for bacterial adaptation and competition.
Area of Science:
- Microbiology
- Bacterial genetics
- Molecular biology
Background:
- Bacteria employ Type VI Secretion Systems (T6SSs) and Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) for inter-bacterial competition and survival.
- Quorum sensing (QS) enables bacteria to coordinate behaviors based on cell density.
- Aliivibrio wodanis possesses two QS systems (LuxS/LuxPQ and AinS/AinR) and a master regulator (LitR), alongside T6SS and CRISPR systems.
Purpose of the Study:
- To investigate the quorum sensing (QS) regulatory mechanisms governing Type VI Secretion Systems (T6SSs) and CRISPR systems in Aliivibrio wodanis.
- To elucidate the roles of QS, cell density, and temperature in the expression of T6SS and CRISPR systems.
- To analyze the impact of QS mutants (ΔainS and ΔlitR) on the regulation of these survival systems.
Main Methods:
- Genome analysis of Aliivibrio wodanis to identify T6SS and CRISPR loci.
- Gene expression profiling (transcriptome analysis) of wild-type and QS mutants (ΔainS, ΔlitR) under varying cell densities and temperatures.
- Comparative analysis of gene expression data to determine QS-dependent regulation.
Main Results:
- Aliivibrio wodanis harbors two CRISPR systems (one lacking cas genes, one type I-F) and three main T6SS clusters with auxiliary clusters and numerous effectors.
- CRISPR system 2 is constitutive, while CRISPR system 1 is temperature-dependent; T6SS clusters are both cell density and temperature-dependent.
- QS regulator LitR influences CRISPR system expression (downregulating CRISPR 1, upregulating CRISPR 2) and differentially affects T6SS clusters; AinS positively impacts CRISPR system 2 and T6SS hallmark genes.
Conclusions:
- Type VI Secretion Systems (T6SSs) and CRISPR systems in Aliivibrio wodanis are significantly regulated by quorum sensing (QS).
- QS plays a critical role in coordinating bacterial survival strategies, including competition and adaptation, in response to environmental cues.
- The interplay between QS, T6SSs, and CRISPRs highlights a complex regulatory network essential for bacterial fitness in natural environments.
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