title: Identification and Characterization of Novel Small RNAs in Rickettsia prowazekii.
abstract: Emerging evidence implicates a critically important role for bacterial small RNAs (sRNAs) as post-transcriptional regulators of physiology, metabolism, stress/adaptive responses, and virulence, but the roles of sRNAs in pathogenic Rickettsia species remain poorly understood. Here, we report on the identification of both novel and well-known bacterial sRNAs in Rickettsia prowazekii, known to cause epidemic typhus in humans. RNA sequencing of human microvascular endothelial cells (HMECs), the preferred targets during human rickettsioses, infected with R. prowazekii revealed the presence of 35 trans-acting and 23 cis-acting sRNAs, respectively. Of these, expression of two trans-acting (Rp_sR17 and Rp_sR60) and one cis-acting (Rp_sR47) novel sRNAs and four well-characterized bacterial sRNAs (RNaseP_bact_a, α-tmRNA, 4.5S RNA, 6S RNA) was further confirmed by Northern blot or RT-PCR analyses. The transcriptional start sites of five novel rickettsial sRNAs and 6S RNA were next determined using 5' RLM-RACE yielding evidence for their independent biogenesis in R. prowazekii. Finally, computational approaches were employed to determine the secondary structures and potential mRNA targets of novel sRNAs. Together, these results establish the presence and expression of sRNAs in R. prowazekii during host cell infection and suggest potential functional roles for these important post-transcriptional regulators in rickettsial biology and pathogenesis.
authors.affiliation: Department of Pathology, University of Texas Medical Branch Galveston, TX, USA.
authors.forename: Casey L C
authors.initials: CL
authors.lastname: Schroeder
authors.affiliation: Department of Pathology, University of Texas Medical Branch Galveston, TX, USA.
authors.forename: Hema P
authors.initials: HP
authors.lastname: Narra
authors.affiliation: Department of Pathology, University of Texas Medical Branch Galveston, TX, USA.
authors.forename: Abha
authors.initials: A
authors.lastname: Sahni
authors.affiliation: Department of Pharmacology, University of Texas Medical Branch Galveston, TX, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Rojas
authors.affiliation: Department of Pharmacology, University of Texas Medical Branch Galveston, TX, USA.
authors.forename: Kamil
authors.initials: K
authors.lastname: Khanipov
authors.affiliation: Department of Pathology, University of Texas Medical Branch Galveston, TX, USA.
authors.forename: Jignesh
authors.initials: J
authors.lastname: Patel
authors.affiliation: Department of Neuroscience, University of Texas at Dallas Dallas, TX, USA.
authors.forename: Riya
authors.initials: R
authors.lastname: Shah
authors.affiliation: Department of Pharmacology, University of Texas Medical Branch Galveston, TX, USA.
authors.forename: Yuriy
authors.initials: Y
authors.lastname: Fofanov
authors.affiliation: Department of Pathology, University of Texas Medical Branch Galveston, TX, USA.
authors.forename: Sanjeev K
authors.initials: SK
authors.lastname: Sahni
keywords: RNA sequencing; Rickettsia prowazekii; epidemic typhus; small RNAs; vascular endothelium