Grewal N, Salunke D M
National Institute of Immunology, New Delhi, India.
FEBS Lett. 1993 May 10;322(2):111-4. doi: 10.1016/0014-5793(93)81548-e.
Bacterial flagellin has two domains: the polymerizing domain consisting of N- and C-terminal regions which are partly disordered in the monomeric state; and the central antigenic domain with compact globular structure. The polymerizing domain is highly conserved in flagellins from different species but the antigenic domain is diverse in sequence and size. Whereas the former has direct functional significance for bacterial motility, the latter has not been identified as having a specific function except for defining the distinct serotype of the bacterium. The sequence alignment of flagellin from S. paratyphi with proteins of known three-dimensional structure reveals significant homology of the central 265 residue stretch with the bacterial serine protease, subtilisin. This homology is evident also in the comparison of the predicted secondary structure of flagellin with the observed secondary structural features in subtilisin. The deletions/insertions arising due to optimal alignment of the two proteins occur on the surface loops in the structure. Thus, a domain of S. paratyphi flagellin and subtilisin appear to have similar structural folds.
聚合结构域，由N端和C端区域组成，在单体状态下部分无序；以及具有紧密球状结构的中央抗原结构域。聚合结构域在不同物种的鞭毛蛋白中高度保守，但抗原结构域在序列和大小上具有多样性。前者对细菌运动具有直接功能意义，而后者除了确定细菌的不同血清型外，尚未被确定具有特定功能。副伤寒沙门氏菌鞭毛蛋白与已知三维结构的蛋白质的序列比对显示，中央265个残基片段与细菌丝氨酸蛋白酶枯草杆菌蛋白酶有显著同源性。这种同源性在鞭毛蛋白的预测二级结构与枯草杆菌蛋白酶中观察到的二级结构特征的比较中也很明显。由于两种蛋白质的最佳比对而产生的缺失/插入发生在结构的表面环上。因此，副伤寒沙门氏菌鞭毛蛋白和枯草杆菌蛋白酶的一个结构域似乎具有相似的结构折叠。
