Department of Microbiology and Immunology, VCU Medical Center, 1112 East Clay Street, Room 101 McGuire Hall, PO Box 980678, Richmond, VA 23298-0678, USA.
Pathog Dis. 2021 Mar 20;79(3). doi: 10.1093/femspd/ftab004.
Periodontal disease (PD) is a progressive inflammatory condition characterized by degradation of the gingival epithelium, periodontal ligament, and alveolar bone ultimately resulting in tooth loss. Treponema denticola is a keystone periopathogen that contributes to immune dysregulation and direct tissue destruction. As periodontal disease develops, T. denticola must adapt to environmental, immunological and physiochemical changes in the subgingival crevice. Treponema denticola produces bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP), an important regulatory nucleotide. While T. denticola encodes several putative diguanylate cyclases (DGCs), none have been studied and hence the biological role of c-di-GMP in oral treponemes remains largely unexplored. Here, we demonstrate that the T. denticola open reading frame, TDE0125, encodes a functional DGC designated as DgcA (Diguanylate cyclase A). The dgcA gene is universal among T. denticola isolates, highly conserved and is a stand-alone GGEEF protein with a GAF domain. Recombinant DgcA converts GTP to c-di-GMP using either manganese or magnesium under aerobic and anaerobic reaction conditions. Size exclusion chromatography revealed that DgcA exists as a homodimer and in larger oligomers. Site-directed mutagenesis of residues that define the putative inhibitory site of DgcA suggest that c-di-GMP production is allosterically regulated. This report is the first to characterize a DGC of an oral treponeme.
牙周病 (PD) 是一种进行性炎症性疾病，其特征为牙龈上皮、牙周韧带和牙槽骨的降解，最终导致牙齿脱落。密螺旋体（T. denticola）是一种关键的牙周病原体，它会导致免疫失调和直接组织破坏。随着牙周病的发展，T. denticola 必须适应龈下沟内的环境、免疫和生理化学变化。T. denticola 产生双-(3'-5')-环二鸟苷单磷酸 (c-di-GMP)，这是一种重要的调节核苷酸。虽然 T. denticola 编码了几个假定的双鸟苷酸环化酶 (DGCs)，但目前尚未对它们进行研究，因此 c-di-GMP 在口腔密螺旋体中的生物学作用仍在很大程度上未被探索。在这里，我们证明 T. denticola 开放阅读框 TDE0125 编码一种功能性 DGC，命名为 DgcA（双鸟苷酸环化酶 A）。dgcA 基因在所有 T. denticola 分离株中都是普遍存在的，高度保守，是一个独立的 GGEEF 蛋白，具有 GAF 结构域。DgcA 在有氧和厌氧反应条件下，使用锰或镁将 GTP 转化为 c-di-GMP。尺寸排阻色谱显示 DgcA 以同源二聚体和更大的寡聚体形式存在。对定义 DgcA 假定抑制位点的残基进行定点突变表明，c-di-GMP 的产生是别构调节的。本报告首次对口腔密螺旋体的 DGC 进行了特征描述。
