Abstract
Leptospira are emerging zoonotic pathogens transmitted from animals to humans typically through contaminated environmental sources of water and soil. Regulatory pathways of pathogenic Leptospira spp. underlying the adaptive response to different hosts and environmental conditions remains elusive. In this study, we provide the first global Transcriptional Start Site (TSS) map of a Leptospira species. RNA was obtained from the pathogen Leptospira interrogans grown at 30°C (optimal in vitro temperature) and 37°C (host temperature) and selectively enriched for 5′ ends of native transcripts. A total of 2865 and 2866 primary TSS (pTSS) were predicted in the genome of L. interrogans at 30 and 37°C, respectively. The majority of the pTSSs were located between 0 and 10 nucleotides from the translational start site, suggesting that leaderless transcripts are a common feature of the leptospiral translational landscape. Comparative differential RNA-sequencing (dRNA-seq) analysis revealed conservation of most pTSS at 30 and 37°C. Promoter prediction algorithms allow the identification of the binding sites of the alternative sigma factor sigma 54. However, other motifs were not identified indicating that Leptospira consensus promoter sequences are inherently different from the Escherichia coli model. RNA sequencing also identified 277 and 226 putative small regulatory RNAs (sRNAs) at 30 and 37°C, respectively, including eight validated sRNAs by Northern blots. These results provide the first global view of TSS and the repertoire of sRNAs in L. interrogans. These data will establish a foundation for future experimental work on gene regulation under various environmental conditions including those in the host.
Highlights
Pathogenic Leptospira spp. are the etiologic agents of leptospirosis, a disease manifesting as a wide range of clinical symptoms
To improve genome annotation and promote our understanding of L. interrogans gene structures and RNAbased regulation, we present here a transcriptional map of the L. interrogans genome including the characterization of primary transcription start sites (TSS), alternative Transcriptional Start Site (TSS), operon organization, and specific DNA sequence motifs located in promoter sequences
RNA-seq data of the most abundant transcripts showed that lipoproteins-encoding genes lipL32, lipL21, lipL41, loa22, and lipL36, 30S and 50S ribosomal subunit proteinsencoding genes, and flagellin-encoding genes were the most highly expressed genes in L. interrogans, which concurs with previous transcriptional and translational analyses (Lo et al, 2006; Malmström et al, 2009)
Summary
Pathogenic Leptospira spp. are the etiologic agents of leptospirosis, a disease manifesting as a wide range of clinical symptoms. A recent study estimates that more than one million severe cases of leptospirosis occur annually, including 60,000 deaths (Costa et al, 2015). Rats are asymptomatic reservoirs of pathogenic Leptospira spp. and contribute to the transmission cycle of the bacteria via bacterial shedding through the urinary tract to environmental sources. Wild, and domestic, can serve as reservoirs and present a range of mild to fatal disease manifestations. Leptospira are typically transmitted to humans by exposure to environmental surface water that is contaminated with the urine of infected animals. Leptospirosis has emerged as a major public health problem, especially in the developing world, due to global climate changes and urban sprawl
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
