Rios-Delgado Gustavo, McReynolds Aubrey K G, Pagella Emma A, Norambuena Javiera, Briaud Paul, Zheng Vincent, Munneke Matthew J, Kim Jisun, Racine Hugo, Carroll Ronan, Zelzion Ehud, Skaar Eric, Bose Jeffrey L, Parker Dane, Lalaouna David, Boyd Jeffrey M
Department of Biochemistry and Microbiology, Rutgers, the State University of New Jersey, New Brunswick, NJ, 08901, USA.
Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center, Kanas City, KS, 66103, USA.
bioRxiv. 2024 Jul 4:2024.07.03.601953. doi: 10.1101/2024.07.03.601953.
has evolved mechanisms to cope with low iron (Fe) availability in host tissues. uses the ferric uptake transcriptional regulator (Fur) to sense titers of cytosolic Fe. Upon Fe depletion, apo-Fur relieves transcriptional repression of genes utilized for Fe uptake. We demonstrate that an Δ mutant has decreased expression of , which codes for the Fe-dependent enzyme aconitase. Decreased expression prevented the Δ mutant from growing with amino acids as sole carbon and energy sources. Suppressor analysis determined that a mutation in , which produces a regulatory RNA, permitted growth by decreasing transcription. The decreased AcnA activity of the Δ mutant was partially relieved by an Δ mutation. Directed mutation of bases predicted to facilitate the interaction between the transcript and IsrR, decreased the ability of IsrR to control expression and IsrR bound to the transcript . IsrR also bound to the transcripts coding the alternate TCA cycle proteins , , , and . Whole cell metal analyses suggest that IsrR promotes Fe uptake and increases intracellular Fe not ligated by macromolecules. Lastly, we determined that Fur and IsrR promote infection using murine skin and acute pneumonia models.
已经进化出应对宿主组织中铁（Fe）可用性低的机制。利用铁摄取转录调节因子（Fur）来感知胞质铁的滴度。铁耗尽时，脱辅基Fur解除对用于铁摄取的基因的转录抑制。我们证明一个Δ突变体中编码铁依赖性酶乌头酸酶的基因表达降低。乌头酸酶AcnA表达降低阻止了Δ突变体以氨基酸作为唯一碳源和能源生长。抑制子分析确定，产生调控RNA的基因发生突变，通过降低AcnA转录而允许生长。Δ突变体降低的AcnA活性通过一个Δ突变而部分缓解。对预测有助于AcnA转录本与IsrR之间相互作用的碱基进行定向突变，降低了IsrR控制AcnA表达的能力，并且IsrR与AcnA转录本结合。IsrR还与编码替代三羧酸循环蛋白、、和的转录本结合。全细胞金属分析表明，IsrR促进铁摄取并增加细胞内未与大分子结合的铁。最后，我们利用小鼠皮肤和急性肺炎模型确定Fur和IsrR促进感染。
