Biology subjects

Drecktrah, D.

Publications and source records attributed to Drecktrah, D..

4 recordsLinked to original sources

bioRxiv2025

Identification of proteins exhibiting in vitro RNA chaperone activity through gradient profiling in the Lyme disease spirochete, Borrelia burgdorferi

RNA-binding proteins (RBPs) play key roles in regulating gene expression in bacteria. However, relatively few RBPs have been discovered and characterized in Borrelia (Borreliella) burgdorferi, the causative agent of Lyme disease. We utilized gradient profiling to identify putative RBPs that co-sediment with small RNAs (sRNAs) and nascent mRNAs. We employed in vitro and in vivo assays to characterize the RNA chaperone activities of several proteins we identified in the gradient profiling. The previously hypothetical proteins BB0749, BB0713 and BB0796, as well as the chemotaxis-related protein CheY2 and the flagella-associated protein FlgV displayed RNA annealing and/or strand displacement activity. Moreover, in vivo Co-IP assays demonstrated BB0749 binds RNA in B. burgdorferi.

molecular biology↗

bioRxiv2025

Dissection of amino acid acquisition pathways in Borrelia burgdorferi uncovers unique physiological responses

Borrelia burgdorferi, the causative agent of Lyme disease, is well known for its unique morphology, physiology, and enzootic lifecycle. Building on previous work that showed peptide transport is essential for viability, we endeavored to more clearly define the impact of peptide starvation on the spirochete and directly compare peptide starvation to targeted free amino acid starvation. Herein, we confirm the ability of a putative GltP, BB0401, to facilitate transport of glutamate and aspartate as well as demonstrate its requirement for cell growth and motility. Using conditional mutants for both peptide transport and BB0401, we characterize these systems throughout the enzootic cycle, both confirming their essential role during murine infection and revealing that they are, surprisingly, dispensable during prolonged colonization of the tick midgut. We broadly define the metabolic perturbations resulting from these amino acid starvation models and show that, even under the most severe amino acid stress, B. burgdorferi is unable to modulate its physiological response via the canonical (p)ppGpp-driven stringent response.

microbiology↗

bioRxiv2024

Characterization and genomic analysis of the Lyme disease spirochete bacteriophage phiBB-1

Lyme disease is a tick-borne infection caused by the spirochete Borrelia (Borreliella) burgdorferi. Borrelia species have highly fragmented genomes composed of a linear chromosome and a constellation of linear and circular plasmids some of which are required throughout the enzootic cycle. Included in this plasmid repertoire by almost all Lyme disease spirochetes are the 32-kb circular plasmid cp32 prophages that are capable of lytic replication to produce infectious virions called {phi}BB-1. While the B. burgdorferi genome contains evidence of horizontal transfer, the mechanisms of gene transfer between strains remain unclear. While we know that {phi}BB-1 transduces cp32 and shuttle vector DNA during in vitro cultivation, the extent of {phi}BB-1 DNA transfer is not clear. Herein, we use proteomics and long-read sequencing to further characterize {phi}BB-1 virions. Our studies identified the cp32 pac region and revealed that {phi}BB-1 packages linear cp32s via a headful mechanism with preferentially packaging of plasmids containing the cp32 pac region. Additionally, we find {phi}BB-1 packages fragments of the linear chromosome and full-length plasmids including lp54, cp26, and others. Furthermore, sequencing of {phi}BB-1 packaged DNA allowed us to resolve the covalently closed hairpin telomeres for the linear B. burgdorferi chromosome and most linear plasmids in strain CA-11.2A. Collectively, our results shed light on the biology of the ubiquitous {phi}BB-1 phage and further implicates {phi}BB-1 in the generalized transduction of diverse genes and the maintenance of genetic diversity in Lyme disease spirochetes.

microbiology↗

bioRxiv2018

DksA controls the response of the Lyme disease spirochete Borrelia burgdorferi to starvation

The pathogenic spirochete Borrelia burgdorferi senses and responds to diverse environmental challenges, including changes in nutrient availability, throughout its enzootic cycle in Ixodes spp. ticks and vertebrate hosts. This study examined the role of DnaK suppressor protein (DksA) in the transcriptional response of B. burgdorferi to starvation. Wild-type and dksA mutant B. burgdorferi strains were subjected to starvation by shifting mid-logarithmic phase cultures grown in BSK II medium to serum-free RPMI medium for 6 h under microaerobic conditions (5% CO2, 3% O2). Microarray analyses of wild-type B. burgdorferi revealed that genes encoding flagellar components, ribosomal proteins, and DNA replication machinery were downregulated in response to starvation. DksA mediated transcriptomic responses to starvation in B. burgdorferi as the dksA-deficient strain differentially expressed only 47 genes in response to starvation compared to the 500 genes differentially expressed in wild-type strains. Consistent with a role for DksA in the starvation response of B. burgdorferi, fewer CFUs were observed for dksA mutant after prolonged starvation in RPMI medium compared to wild-type B. burgdorferi. Transcriptomic analyses revealed a partial overlap between the DksA regulon and the regulon of RelBbu, the guanosine tetraphosphate and guanosine pentaphosphate [(p)ppGpp] synthetase that controls the stringent response; the DksA regulon also included many plasmid-borne genes. Additionally, the dksA mutant strain exhibited constitutively elevated (p)ppGpp levels compared to the wild-type strain, implying a regulatory relationship between DksA and (p)ppGpp. Together, these data indicate that DksA along with (p)ppGpp direct the stringent response to effect B. burgdorferi adaptation to its environment.\n\nIMPORTANCEThe Lyme disease bacterium Borrelia burgdorferi must sense and respond to diverse environments as it cycles between its tick vectors and various vertebrate hosts. B. burgdorferi must withstand prolonged periods of starvation while it resides in unfed Ixodes ticks. In this study, the regulatory protein DksA is shown to play a pivotal role controlling the transcriptional responses of B. burgdorferi to starvation. The results of this study suggest that DksA gene regulatory activity impacts B. burgdorferi metabolism, virulence gene expression, and the ability of this bacterium to complete its natural life cycle.

microbiology↗