Department of Periodontics, School of Dental Medicine, Case Western Reserve University, Cleveland, OH 44106, USA.
FEBS Lett. 2012 Jan 2;586(1):1-6. doi: 10.1016/j.febslet.2011.10.047. Epub 2011 Nov 19.
FadA, a novel adhesin of periodontal pathogen Fusobacterium nucleatum is composed of two forms, pre-FadA and mature FadA (mFadA), constituting the functional FadA complex (FadAc). By electron microscopy, we observed that mFadA formed uniformly long and thin filaments, while FadAc formed heterogeneous filaments of varying lengths and widths, as well as "knots". Mutants in signal peptide or in the non-alpha-helical loop retaining heterogeneous structures had binding activity while those forming aggregates or long filaments lost activity. These observations suggest short filaments and knots may be the active forms of FadA. This is the first demonstration that a signal peptide is required for the assembly of a bacterial adhesin.
牙周致病菌福赛斯坦纳菌的新型黏附素 FadA 由两种形式组成，即前 FadA 和成熟 FadA（mFadA），构成功能 FadA 复合物（FadAc）。通过电子显微镜观察，我们发现 mFadA 形成均匀的长而细的纤维，而 FadAc 则形成不同长度和宽度的异质纤维，以及“结”。信号肽缺失或非α-螺旋环缺失的突变体仍具有结合活性，而形成聚集物或长纤维的突变体则失去活性。这些观察结果表明，短纤维和结可能是 FadA 的活性形式。这是首次证明信号肽是细菌黏附素组装所必需的。
