Leptospirosis is a global re-emerging zoonosis, caused by pathogenic bacteria of the genus Leptospira. Humans are infected mainly through contact with contaminated water or soil. The understanding of the molecular mechanisms of leptospirosis through the characterization of unknown outer membrane proteins may contribute to the development of new treatments, diagnostic methods and vaccines. We have identified using bioinformatics analysis a protein that is encoded by the gene LIC10774, predicted to be localized at the leptospiral outer membrane and exhibit beta-roll folding. Surface exposure was confirmed by flow cytometry, ELISA and immunofluorescence-based confocal microscopy. Through circular dichroism spectroscopy and hydrophobic dye binding we have shown that rLIC10774 binds calcium ions, which imposes changes to secondary and tertiary structures. The recombinant protein was capable of binding to several host extracellular matrix and serum components. Therefore, we describe LIC10774 as a calcium-binding protein exposed in the outer surface of pathogenic leptospires with possible multifunctional roles in adhesion to host tissues, evasion of the immune system and participation in dissemination processes during leptospirosis. In addition, we hypothesize that the calcium binding is important for temperature-dependent functional roles during leptospirosis.

钩端螺旋体病是一种由钩端螺旋体属的致病菌引起的全球性重新出现的人畜共患病。感染人类的​​主要途径是接触被污染的水或土壤。通过表征未知的外膜蛋白来了解钩端螺旋体病的分子机制，可能有助于开发新的治疗方法，诊断方法和疫苗。我们已经使用生物信息学分析确定了一种蛋白质，该蛋白质由基因LIC10774编码，预计会位于钩端螺旋体外膜上并表现出β卷折叠。通过流式细胞仪，ELISA和基于免疫荧光的共聚焦显微镜确认表面暴露。通过圆二色光谱和疏水性染料结合，我们已经证明rLIC10774与钙离子结合，从而对二级和三级结构施加了变化。重组蛋白能够结合几种宿主细胞外基质和血清成分。因此，我们将LIC10774描述为一种钙结合蛋白，暴露于致病性钩端螺旋体的外表面，在与宿主组织的粘附，逃避免疫系统以及参与钩端螺旋体病的传播过程中可能具有多种作用。此外，我们假设钙结合对于钩端螺旋体病期间温度依赖性功能的作用很重要。