Evolutionary trends in Bombella apis CRISPR-Cas systems.

Area of Science:

• Microbiology
• Immunology
• Genomics

Background:

• Bacteria and archaea utilize CRISPR-Cas systems for defense against foreign genetic elements like bacteriophages.
• Bombella apis, a honey bee symbiont, harbors CRISPR-Cas systems, with its roles in the colony, including brood protection and nutritional support, being understudied.
• Niche specificity of B. apis may be influenced by bacteriophage and mobile genetic element (MGE) pressures within different honey bee colony environments.

Purpose of the Study:

• To investigate the variation and distribution of CRISPR-Cas types within B. apis strains.
• To analyze spacer sequences for insights into MGE interactions and the evolutionary history of B. apis CRISPR-Cas systems.
• To predict interactions between viral sequences and CRISPR systems across different honey bee microbiome members.

Main Methods:

• Genomic analysis of CRISPR-Cas types and arrays in B. apis strains.
• Metagenomic analysis of CRISPR-Cas systems in honey bee queen gut samples.
• Spacer analysis to infer MGE interaction history.
• Bioinformatic prediction of viral sequence and CRISPR system interactions.

Main Results:

• Multiple CRISPR-Cas types, some with multiple arrays, were identified within individual B. apis genomes and honey bee queen gut metagenomes.
• Spacer analysis revealed unique sequences among strains, supporting the functional role of CRISPR-Cas systems in distinct niches.
• Evidence suggests dynamic acquisition of new spacers across multiple genomic locations, indicating a flexible antiviral defense strategy for B. apis.

Conclusions:

• B. apis CRISPR-Cas systems are highly dynamic and play a functional role in microbial defense within the honey bee colony.
• The unique spacer compositions in different niches highlight niche-specific selective pressures from MGEs.
• The flexible nature of CRISPR-Cas systems in B. apis contributes to its adaptation and survival within the complex honey bee microbiome.