Crystal structure of the type VI immunity protein Tdi1 (Atu4351) from Agrobacterium tumefaciens
Crystal structure of the type VI immunity protein Tdi1 (Atu4351) from Agrobacterium tumefaciens
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根癌农杆菌 VI 型免疫蛋白 Tdi1 (Atu4351) 的晶体结构
DOI：
10.1107/s2053230x19000815
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发表时间：
2019
影响因子：
0.9
通讯作者：
Dong Yuhui
中科院分区：
文献类型：
--
作者：
Shi Lingling;Gao Zengqiang;Zhang Tianyi;Zhang Heng;Dong Yuhui
VI型分泌系统（T6 SS）是一种广泛存在于革兰氏阴性菌中的新型多蛋白针状结构。携带T6 SSs的细菌将各种效应物注入真核和原核细胞，用于种间竞争或毒力相关过程。效应物的毒性可被其同源免疫蛋白中和。Tde 1（Atu 4350）-Tdi 1（Atu 4351）最近被表征为土壤细菌根癌农杆菌中的T6 SS效应免疫对，并且中和机制仍然未知。在此，通过单波长反常色散法以2.40 nm的分辨率测定免疫蛋白质Tdi 1的晶体结构。 结构分析表明，它是由一个GAD样结构域和一个插入DUF 1851结构域，这两个结构域显示低的结构相似性，以已知的结构。有一个主要位于GAD样结构域的正沟，可能与核苷酸结合有关。该结构为进一步研究正沟作为潜在活性位点提供了基础。
The type VI secretion system (T6SS) is a novel multiprotein needle-like apparatus that is distributed widely in Gram-negative bacteria. Bacteria harboring T6SSs inject various effectors into both eukaryotic and prokaryotic cells for interspecies competition or virulence-related processes. The toxicities of the effectors can be neutralized by their cognate immunity proteins. Tde1 (Atu4350)–Tdi1 (Atu4351) has recently been characterized as a T6SS effector–immunity pair in the soil bacterium Agrobacterium tumefaciens and the neutralization mechanism remains unknown. Here, the crystal structure of the immunity protein Tdi1 was determined at 2.40 Å resolution by the single-wavelength anomalous dispersion method. Structural analysis suggested that it is composed of a GAD-like domain and an inserted DUF1851 domain, and both domains show low structural similarities to known structures. There is a positive groove mainly located in the GAD-like domain that may be associated with nucleotide binding. The structure provides a basis for further study of the positive groove as a potential active site.