分类： 生物学 >> 生物物理学 >> 生物物理、生物化学与分子生物学 提交时间： 2016-05-12
Xu, Chengchen
Meng, Ying
Yu, Ziniu
Sun, Ming
Xu, Chengchen
Chinte, Unmesh
Chen, Lirong
Zhou, Dayong
Rose, John
Adang, Michael J.
Wang, Bi-Cheng
Chinte, Unmesh
Rose, John
Wang, Bi-Cheng
Chinte, Unmesh
Rose, John
Wang, Bi-Cheng
Yao, Qingqing
Bi, Li-Jun
Adang, Michael J.
摘要： The structures of several Bacillus thuringiensis (Bt) insecticidal crystal proteins have been determined by crystallographic methods and a close relationship has been explicated between specific toxicities and conserved three-dimensional architectures. In this study, as a representative of the coleopteran- and hemipteran-specific Cry51A group, the complete structure of Cry51Aa1 protoxin has been determined by X-ray crystallography at 1.65 angstrom resolution. This is the first report of a coleopteran-active Bt insecticidal toxin with high structural similarity to the aerolysin-type beta-pore forming toxins (beta-FFTs). Moreover, study of featured residues and structural elements reveal their possible roles in receptor binding and pore formation events. This study provides new insights into the action of aerolysin-type (beta-PFTs from a structural perspective, and could be useful for the control of coleopteran and hemipteran insect pests in agricultures. (C) 2015 Elsevier Inc. All rights reserved.
分类： 生物学 >> 生物物理学 >> 生物物理、生物化学与分子生物学 提交时间： 2016-05-12
Zhang, Xiao-Li
Zhang, Xian-En
Zhang, Xiao-Li
Li, De-Feng
Fleming, Joy
Wang, Li-Wei
Zhou, Ying
Wang, Da-Cheng
Zhang, Xian-En
Bi, Li-Jun
Zhang, Xiao-Li
Li, De-Feng
Fleming, Joy
Wang, Li-Wei
Zhou, Ying
Wang, Da-Cheng
Zhang, Xian-En
Bi, Li-Jun
Zhang, Xiao-Li
摘要： Pathogenic mycobacteria transport virulence factors across their complex cell wall via a type VII secretion system (T7SS)/early secreted antigenic target-6 of kDa secretion system (ESX). ESX conserved component (Ecc) B, a core component of the T7SS architecture, is predicted to be a membrane bound protein, but little is known about its structure and function. Here, we characterize EccB1, showing that it is an ATPase with no sequence or structural homology to other ATPases located in the cell envelope of Mycobacterium tuberculosis H37Rv. We obtained the crystal structure of an EccB1-DN72 truncated transmembrane helix and performed modeling and ATP docking studies, showing that EccB1 likely exists as a hexamer. Sequence alignment and ATPase activity determination of EccB1 homologues indicated the presence of 3 conserved motifs in the N- and C-terminals of EccB1-DN72 that assemble together between 2 membrane proximal domains of the EccB1-DN72 monomer. Models of the EccB1 hexamer show that 2 of the conserved motifs are involved in ATPase activity and form an ATP binding pocket located on the surface of 2 adjacent molecules. Our results suggest that EccB may act as the energy provider in the transport of T7SS virulence factors and may be involved in the formation of a channel across the mycomembrane.
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