TY - JOUR
T1 - The intervening sequence of coxiella burnetii
T2 - Characterization and evolution
AU - Warrier, Indu
AU - Walter, Mathias C.
AU - Frangoulidis, Dimitrios
AU - Raghavan, Rahul
AU - Hicks, Linda D.
AU - Minnick, Michael F.
N1 - Publisher Copyright:
© 2016 Warrier, Walter, Frangoulidis, Raghavan, Hicks and Minnick.
PY - 2016/8/19
Y1 - 2016/8/19
N2 - The intervening sequence (IVS) of Coxiella burnetii, the agent of Q fever, is a 428-nt selfish genetic element located in helix 45 of the precursor 23S rRNA. The IVS element, in turn, contains an ORF that encodes a hypothetical ribosomal S23 protein (S23p). Although S23p can be synthesized in vitro in the presence of an engineered E. coli promoter and ribosome binding site, results suggest that the protein is not synthesized in vivo. In spite of a high degree of IVS conservation among different strains of C. burnetii, the region immediately upstream of the S23p start codon is prone to change, and the S23p-encoding ORF is evidently undergoing reductive evolution. We determined that IVS excision from 23S rRNA was mediated by RNase III, and IVS RNA was rapidly degraded, thereafter. Levels of the resulting 23S rRNA fragments that flank the IVS, F1 (~1.2 kb) and F2 (~1.7 kb), were quantified over C. burnetii's logarithmic growth phase (1-5 d). Results showed that 23S F1 quantities were consistently higher than those of F2 and 16S rRNA. The disparity between levels of the two 23S rRNA fragments following excision of IVS is an interesting phenomenon of unknown significance. Based upon phylogenetic analyses, IVS was acquired through horizontal transfer after C. burnetii's divergence from an ancestral bacterium and has been subsequently maintained by vertical transfer. The widespread occurrence, maintenance and conservation of the IVS in C. burnetii imply that it plays an adaptive role or has a neutral effect on fitness.
AB - The intervening sequence (IVS) of Coxiella burnetii, the agent of Q fever, is a 428-nt selfish genetic element located in helix 45 of the precursor 23S rRNA. The IVS element, in turn, contains an ORF that encodes a hypothetical ribosomal S23 protein (S23p). Although S23p can be synthesized in vitro in the presence of an engineered E. coli promoter and ribosome binding site, results suggest that the protein is not synthesized in vivo. In spite of a high degree of IVS conservation among different strains of C. burnetii, the region immediately upstream of the S23p start codon is prone to change, and the S23p-encoding ORF is evidently undergoing reductive evolution. We determined that IVS excision from 23S rRNA was mediated by RNase III, and IVS RNA was rapidly degraded, thereafter. Levels of the resulting 23S rRNA fragments that flank the IVS, F1 (~1.2 kb) and F2 (~1.7 kb), were quantified over C. burnetii's logarithmic growth phase (1-5 d). Results showed that 23S F1 quantities were consistently higher than those of F2 and 16S rRNA. The disparity between levels of the two 23S rRNA fragments following excision of IVS is an interesting phenomenon of unknown significance. Based upon phylogenetic analyses, IVS was acquired through horizontal transfer after C. burnetii's divergence from an ancestral bacterium and has been subsequently maintained by vertical transfer. The widespread occurrence, maintenance and conservation of the IVS in C. burnetii imply that it plays an adaptive role or has a neutral effect on fitness.
KW - Coxiella
KW - IVS
KW - Intervening sequence
KW - RNA
KW - S23 protein
UR - http://www.scopus.com/inward/record.url?scp=84990060804&partnerID=8YFLogxK
U2 - 10.3389/fcimb.2016.00083
DO - 10.3389/fcimb.2016.00083
M3 - Article
C2 - 27595093
AN - SCOPUS:84990060804
SN - 2235-2988
VL - 6
JO - Frontiers in Cellular and Infection Microbiology
JF - Frontiers in Cellular and Infection Microbiology
IS - AUG
M1 - 83
ER -