Composition and Activity of the Non-canonical Gram-positive SecY2 Complex.
Composition and Activity of the Non-canonical Gram-positive SecY2 Complex.
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DOI：
10.1074/jbc.m116.729806
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发表时间：
2016-10-07
期刊：
影响因子：
--
通讯作者：
Collinson I
中科院分区：
文献类型：
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作者：
Bandara M;Corey RA;Martin R;Skehel JM;Blocker AJ;Jenkinson HF;Collinson I
戈登链球菌DL 1的辅助Sec系统是一个专门的输出系统，将富含丝氨酸的大重复蛋白Hsa转运到细菌表面。该系统由核心蛋白SecA 2和SecY 2以及辅助蛋白Sec 1-Asp 5组成。与典型的SecYEG类似，SecY 2形成了Hsa粘附素跨细胞质膜易位的通道。辅助Sec蛋白Asp 4和Asp 5被认为与SecY 2一起工作以形成易位子，类似于典型系统（SecYEG）的相关SecY、SecE和SecG。为了验证这一理论，S。戈登氏菌secY 2、asp 4和asp 5在大肠杆菌中共表达。随后纯化所得复合物，并且通过质谱法确认其组成为SecY 2-Asp 4-Asp 5。与SecYEG一样，非典型复合物激活SecA马达（SecA 2）的ATP酶活性。本研究还表明，Asp 4和Asp 5是S. gordonii与糖蛋白gp 340和纤连蛋白（已知的Hsa结合配偶体）的结合，以及用于早期生物膜形成。这项工作为理解辅助Sec系统的结构和功能开辟了新的途径。
The accessory Sec system in Streptococcus gordonii DL1 is a specialized export system that transports a large serine-rich repeat protein, Hsa, to the bacterial surface. The system is composed of core proteins SecA2 and SecY2 and accessory Sec proteins Asp1–Asp5. Similar to canonical SecYEG, SecY2 forms a channel for translocation of the Hsa adhesin across the cytoplasmic membrane. Accessory Sec proteins Asp4 and Asp5 have been suggested to work alongside SecY2 to form the translocon, similar to the associated SecY, SecE, and SecG of the canonical system (SecYEG). To test this theory, S. gordonii secY2, asp4, and asp5 were co-expressed in Escherichia coli. The resultant complex was subsequently purified, and its composition was confirmed by mass spectrometry to be SecY2-Asp4-Asp5. Like SecYEG, the non-canonical complex activates the ATPase activity of the SecA motor (SecA2). This study also shows that Asp4 and Asp5 are necessary for optimal adhesion of S. gordonii to glycoproteins gp340 and fibronectin, known Hsa binding partners, as well as for early stage biofilm formation. This work opens new avenues for understanding the structure and function of the accessory Sec system.