Temperature-dependent sRNA transcriptome of the Lyme disease spirochete

Area of Science:

• Bacteriology
• Molecular Biology
• Genomics
• RNA Biology

Background:

• Borrelia burgdorferi, the causative agent of Lyme disease, undergoes significant gene expression changes during transmission from tick vectors to mammalian hosts.
• Small regulatory RNAs (sRNAs) are increasingly recognized as key regulators of bacterial gene expression, but their role in B. burgdorferi has been largely unexplored, with only one characterized sRNA prior to this study.

Purpose of the Study:

• To comprehensively identify and characterize the small RNA transcriptome of Borrelia burgdorferi.
• To investigate the differential expression of sRNAs at temperatures mimicking tick-to-mammalian host transmission (23°C and 37°C).
• To understand the potential regulatory roles of identified sRNAs in B. burgdorferi adaptation and pathogenesis.

Main Methods:

• Employed an sRNA-specific deep-sequencing approach to profile the small RNA transcriptome of B. burgdorferi.
• Collected and analyzed RNA samples at two distinct temperatures: 23°C (tick-like) and 37°C (mammalian host-like).
• Validated RNA sequencing findings for selected sRNAs using Northern blot analyses.

Main Results:

• Identified over 1000 sRNAs in B. burgdorferi, including novel antisense, intragenic, intergenic, and 5' UTR-associated sRNAs.
• Discovered that 43% of the identified sRNAs are temperature-dependent, exhibiting differential expression between 23°C and 37°C.
• Found associations between antisense or 5' UTR sRNAs and genes critical for Borrelia's enzootic cycle maintenance.

Conclusions:

• sRNAs are abundant and dynamically expressed in B. burgdorferi, playing a common role in environmental adaptation and gene regulation.
• The discovery of numerous antisense and intragenic sRNAs has implications for genetic studies, potentially affecting loss-of-function analyses and revealing expanded coding potential in the B. burgdorferi genome.
• An interactive online database (http://www.cibiv.at/~niko/bbdb/) was created to provide public access to the RNA-seq data, facilitating further research.