Subjects: Biology >> Biophysics >> Biochemistry & Molecular Biology submitted time 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.
Abstract： 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.
Peer Review Status:
Awaiting Review
Subjects: Biology >> Biophysics submitted time 2016-05-12
Wang, Xu-Ying
Wang, Dian-Bing
Bi, Li-Jun
Zhang, Xian-En
Wang, Xu-Ying
Zhang, Ji-Bin
Zhang, Zhi-Ping
Ding, Wei
Abstract： S-layer proteins create a cell-surface layer architecture in both bacteria and archaea. Because S-layer proteins self-assemble into a native-like S-layer crystalline structure in vitro, they are attractive building blocks in nanotechnology. Here, the potential use of the S-layer protein EA1 from Bacillus anthracis in constructing a functional nanostructure is investigated, and apply this nanostructure in a proof-of-principle study for serological diagnosis of anthrax. EA1 is genetically fused with methyl parathion hydrolase (MPH), to degrade methyl parathion and provide a label for signal amplifi cation. EA1 not only serves as a nanocarrier, but also as a specific antigen to capture anthrax-specific antibodies. As results, purified EA1-MPH forms a single layer of crystalline nanostructure through self-assembly. Our chimeric nanocatalyst greatly improves enzymatic stability of MPH. When applied to the detection of anthrax-specific antibodies in serum samples, the detection of our EA1-MPH nanostructure is nearly 300 times more sensitive than that of the unassembled complex. Together, it is shown that it is possible to build a functional and highly sensitive nanosensor based on S-layer protein. In conclusion, our present study should serve as a model for the development of other multifunctional nanomaterials using S-layer proteins.
Peer Review Status:Awaiting Review
Subjects: Biology >> Biophysics submitted time 2016-05-12
Abstract： Rv0880 from the pathogen Mycobacterium tuberculosis is classified as a MarR family protein in the Pfam database. It consists of 143 amino acids and has an isoelectric point of 10.9. Crystals of Rv0880 belonged to space group P1, with unit-cell parameters a = 54.97, b = 69.60, c = 70.32 angstrom, alpha = 103.71, beta = 111.06, gamma = 105.83 degrees. The structure of the MarR family transcription regulator Rv0880 was solved at a resolution of 2.0 angstrom with an R-cryst and R-free of 21.2 and 24.9%, respectively. The dimeric structure resembles that of other MarR proteins, with each subunit comprising a winged helix-turn-helix domain connected to an alpha-helical dimerization domain.
Peer Review Status:Awaiting Review
Subjects: Biology >> Biophysics >> Biochemistry & Molecular Biology submitted time 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
Abstract： 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.
Peer Review Status:Awaiting Review
Subjects: Biology >> Biophysics submitted time 2016-05-11
Wang, Dian-Bing
Fleming, Joy
Bi, Li-Jun
Zhang, Xian-En
Tian, Bo
Zhang, Zhi-Ping
Wang, Xu-Ying
Tian, Bo
Yang, Rui-Fu
Abstract： Detection of Bacillus anthracis in the field, whether as a natural infection or as a biothreat remains challenging. Here we have developed a new lateral-flow immunochromatographic assay (LFIA) for B. anthracis spore detection based on the fact that conjugates of B. anthracis spores and super-paramagnetic particles labeled with antibodies will block the pores of chromatographic strips and form retention lines on the strips, instead of the conventionally reported test lines and control lines in classic LFIA. As a result, this new LFIA can simultaneously realize optical, magnetic and naked-eye detection by analyzing signals from the retention lines. As few as 500-700 pure B. anthracis spores can be recognized with CV values less than 8.31% within 5 min of chromatography and a total time of 20 min. For powdery sample tests, this LFIA can endure interference from 25% (w/v) milk, 10% (w/v) baking soda and 10% (w/v) starch without any sample pre-treatment, and has a corresponding detection limit of 6 x 10(4) spores/g milk powder, 2 x 10(5) spores/g starch and 5 x 10(5) spores/g baking soda. Compared with existing methods, this new approach is very competitive in terms of sensitivity, specificity, cost and ease of operation. This proof-of-concept study can also be extended for detection of many other large-sized analytes. (C) 2014 The Authors. Published by Elsevier B.V.
Peer Review Status:Awaiting Review
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