Shen Li, Diggs Caitlynn, Ferdous Shomita, Santos Amanda, Wolf Neol, Terrebonne Andrew, Carvajal Luis Lorenzo, Zhong Guangming, Ouellette Scot P, Tse-Dinh Yuk-Ching
Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA.
Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA.
bioRxiv. 2024 Dec 3:2024.12.03.626651. doi: 10.1101/2024.12.03.626651.
The obligate intracellular bacterial pathogen, (Ct), has a distinct DNA topoisomerase I (TopA) with a C-terminal domain (CTD) homologous to eukaryotic SWIB domains. Despite the lack of sequence similarity at the CTDs between TopA (CtTopA) and TopA (EcTopA), full-length CtTopA removed negative DNA supercoils and complemented the growth defect of an mutant. We demonstrated that CtTopA is less processive in DNA relaxation than EcTopA in dose-response and time course studies. An antibody generated against the SWIB domain of CtTopA specifically recognized CtTopA but not EcTopA or TopA (MtTopA), consistent with the sequence differences in their CTDs. The endogenous CtTopA protein is expressed at a relatively high level during the middle and late developmental stages of . Conditional knockdown of expression using CRISPRi in resulted in not only a developmental defect but also in the downregulation of genes linked to nucleotide acquisition from the host cells. Because SWIB-containing proteins are not found in prokaryotes beyond spp., these results imply a significant function for the SWIB-containing CtTopA in facilitating the energy metabolism of for its unique intracellular growth.
专性细胞内细菌病原体沙眼衣原体（Ct）具有一种独特的DNA拓扑异构酶I（TopA），其C端结构域（CTD）与真核生物的SWIB结构域同源。尽管沙眼衣原体TopA（CtTopA）和大肠杆菌TopA（EcTopA）的CTD之间缺乏序列相似性，但全长CtTopA能够消除负性DNA超螺旋，并弥补大肠杆菌突变体的生长缺陷。我们在剂量反应和时间进程研究中证明，CtTopA在DNA松弛过程中的持续性低于EcTopA。针对CtTopA的SWIB结构域产生的抗体能特异性识别CtTopA，而不能识别EcTopA或结核分枝杆菌TopA（MtTopA），这与它们CTD中的序列差异一致。内源性CtTopA蛋白在沙眼衣原体发育的中后期阶段以相对较高的水平表达。在沙眼衣原体中使用CRISPRi条件性敲低CtTopA的表达，不仅导致发育缺陷，还导致与从宿主细胞获取核苷酸相关的基因下调。由于除了衣原体属之外，在原核生物中未发现含SWIB的蛋白，这些结果表明含SWIB的CtTopA在促进沙眼衣原体独特的细胞内生长的能量代谢中具有重要功能。
