Anselmi Natalie K, Vanyo Stephen T, Clark Nicholas D, Rodriguez Dayron M Leyva, Jones Megan M, Rosenthal Sara, Patel Dhara, Marconi Richard T, Visser Michelle B
Department of Oral Biology, School of Dental Medicine, University at Buffalo, The State University of New York, Buffalo, New York, USA.
Department of Structural Biology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, The State University of New York, Buffalo, New York, USA.
Mol Oral Microbiol. 2025 Feb;40(1):17-36. doi: 10.1111/omi.12484. Epub 2024 Sep 12.
Numerous Treponema species are prevalent in the dysbiotic subgingival microbial community during periodontitis. The major outer sheath protein is a highly expressed virulence factor of the well-characterized species Treponema denticola. Msp forms an oligomeric membrane protein complex with adhesin and porin properties and contributes to host-microbial interaction. Treponema maltophilum and Treponema lecithinolyticum species are also prominent during periodontitis but are relatively understudied. Msp-like membrane surface proteins exist in T. maltophilum (MspA) and T. lecithinolyticum (MspTL), but limited information exists regarding their structural features or functionality. Protein profiling reveals numerous differences between these species, but minimal differences between strains of the same species. Using protein modeling tools, we predict MspA and MspTL monomeric forms to be large β-barrel structures composed of 20 all-next-neighbor antiparallel β strands which most likely adopt a homotrimer formation. Using cell fractionation, Triton X-114 phase partitioning, heat modifiability, and chemical and detergent release assays, we found evidence of amphiphilic integral membrane-associated oligomerization for both native MspA and MspTL in intact spirochetes. Proteinase K accessibility and immunofluorescence assays demonstrate surface exposure of MspA and MspTL. Functionally, purified recombinant MspA or MspTL monomer proteins can impair neutrophil chemotaxis. Expressions of MspA or MspTL with a PelB leader sequence in Escherichia coli also demonstrate surface exposure and can impair neutrophil chemotaxis in an in vivo air pouch model of inflammation. Collectively, our data demonstrate that MspA and MspTL membrane proteins can contribute to pathogenesis of these understudied oral spirochete species.
在牙周炎期间，多种密螺旋体物种在功能失调的龈下微生物群落中普遍存在。主要外鞘蛋白是特征明确的齿垢密螺旋体的一种高表达毒力因子。Msp形成一种具有粘附素和孔蛋白特性的寡聚膜蛋白复合物，并有助于宿主与微生物的相互作用。嗜麦芽密螺旋体和溶卵磷脂密螺旋体物种在牙周炎期间也很突出，但相对研究较少。嗜麦芽密螺旋体（MspA）和溶卵磷脂密螺旋体（MspTL）中存在类似Msp的膜表面蛋白，但关于它们的结构特征或功能的信息有限。蛋白质谱分析揭示了这些物种之间存在许多差异，但同一物种的菌株之间差异极小。使用蛋白质建模工具，我们预测MspA和MspTL单体形式为大型β桶结构，由20条全相邻反平行β链组成，很可能形成同三聚体。通过细胞分级分离法、Triton X-114相分配法、热可变性以及化学和去污剂释放试验，我们发现完整螺旋体中天然MspA和MspTL均存在两亲性整合膜相关寡聚化的证据。蛋白酶K可及性和免疫荧光试验证明了MspA和MspTL的表面暴露。在功能上，纯化的重组MspA或MspTL单体蛋白可损害中性粒细胞趋化性。在大肠杆菌中表达带有PelB前导序列的MspA或MspTL也证明了表面暴露，并且在体内炎症气囊模型中可损害中性粒细胞趋化性。总体而言，我们的数据表明，MspA和MspTL膜蛋白可促成这些研究较少的口腔螺旋体物种的发病机制。
