Borrelia burgdorferi SpoVG DNA- and RNA-Binding Protein Modulates the Physiology of the Lyme Disease Spirochete

Abstract

The SpoVG protein of , the Lyme disease spirochete, binds to specific sites of DNA and RNA. The bacterium regulates transcription of during the natural tick-mammal infectious cycle and in response to some changes in culture conditions. Bacterial levels of mRNA and SpoVG protein did not necessarily correlate, suggesting that posttranscriptional mechanisms also control protein levels. Consistent with this, SpoVG binds to its own mRNA, adjacent to the ribosome-binding site. SpoVG also binds to two DNA sites in the operon and to two RNA sites in mRNA; that operon encodes genes necessary for glycerol catabolism and is important for colonization in ticks. In addition, spirochetes engineered to dysregulate exhibited physiological alterations. persists in nature by cycling between ticks and vertebrates. Little is known about how the bacterium senses and adapts to each niche of the cycle. The present studies indicate that controls production of SpoVG and that this protein binds to specific sites of DNA and RNA in the genome and transcriptome, respectively. Altered expression of exerts effects on bacterial replication and other aspects of the spirochete's physiology.

Transcriptomic insights on the virulence-controlling CsrA, BadR, RpoN, and RpoS regulatory networks in the Lyme disease spirochete

“…The operon encoding import and catabolism of glycerol consists of four genes glpF , glpK , an ORF of unknown function (ORF BB_0242 ), and glpD [ 18 , 70 , 71 ]. The glpFKD operon appears to be under complex control, being reported to be impacted by several regulatory factors, including RpoS, SpoVG, cyclic-di-GMP, and ppGpp [ 70 , 72 – 74 ]. In addition, an antisense RNA that is transcribed within the glpF ORF, ncRNA0042 , was recently identified in two independent studies [ 30 , 50 ].…”

“…BadR and CsrA are known nucleic acid-binding proteins and could mediate all of the DE transcript changes directly. However, both mutants exhibited altered expression of spoVG , which encodes a regulatory protein with site-specific DNA-/RNA-binding activity [ 74 – 76 ]. The mRNA encoding SpoVG was significantly increased by 3-fold in the badR mutant and 2.3-fold in the csrA mutant.…”

The Lyme disease spirochete's BpuR DNA/RNA‐binding protein is differentially expressed during the mammal–tick infectious cycle, which affects translation of the SodA superoxide dismutase

“…DNA and RNA EMSAs were performed essentially as described previously (Babb et al , ; Riley et al , ; Jutras et al , ; Savage et al , ). Binding reactions took place in EMSA binding buffer (50 mM Tris, 1 mM EDTA, 1 mM DTT, 10% Glycerol, 2.4% Protease inhibitor cocktail and 0.6% phosphatase inhibitor cocktail) with 1nM biotin‐labeled DNA probe and either cellular extract or purified protein.…”

“…Recently, it has become obvious that the Lyme spirochete also uses posttranscriptional mechanisms to regulate protein levels. These mechanisms include RNA-binding proteins and noncoding RNAs that alter translation of mRNAs, enzymatic modifications of proteins and factors that change the stability of target proteins (Lybecker and Samuels, 2007;Karna et al, 2011;Salman-Dilgimen et al, 2011;Sze et al, 2011;Dulebohn et al, 2014;Lybecker and Samuels, 2017;Popitsch et al, 2017;Bontemps-Gallo et al, 2018;Savage et al, 2018).…”

The intergenic small non-coding RNA ittA is required for optimal infectivity and tissue tropism in Borrelia burgdorferi

“…In B. burgdorferi, several transcriptional regulators have been identified and characterized, as well as a growing list of DNA interacting proteins, which serve to alter borrelial gene expression either directly or indirectly [3,[20][21][22][23][24][25][26][27][28][29][30][31][32][33]. Many of these regulators govern, in part, the production of surface proteins involved in borrelial virulence [20,[34][35][36][37].…”