Cryo-EM analysis of the organization of BclA and BxpB in the Bacillus anthracis exosporium.
Cryo-EM analysis of the organization of BclA and BxpB in the Bacillus anthracis exosporium.
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DOI：
10.1016/j.jsb.2014.02.018
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发表时间：
2014-04
影响因子：
3
通讯作者：
Dokland, Terje
中科院分区：
文献类型：
--
作者：
Rodenburg, Cynthia M.;McPherson, Sylvia A.;Turnbough, Charles L., Jr.;Dokland, Terje
关键词：
炭疽芽孢杆菌和其他致病性芽孢杆菌形成孢子，孢子被外孢子包围，外孢子是一个气球状的层，作为孢子的外部渗透性屏障，有助于孢子的存活和毒力。外孢子囊由毛状绒毛和准晶基底层组成。绒毛的细丝由胶原样糖蛋白BclA的三聚体组成，而基底层含有大约20种不同的蛋白质。其中一种蛋白质，BxpB，与BclA形成紧密的复合物，是基本所有BclA细丝附着到基底层所必需的。另一种基底层蛋白，ExsB，是外孢子与孢子稳定附着所必需的。为了确定BclA和BxpB在孢子内的组织结构，我们使用冷冻电镜、冷冻切片和晶体学分析了阴性染色的孢子外孢子片段，比较了野生型孢子和缺乏BclA、BxpB或ExsB的突变孢子（分别为ΔbclA、ΔbxpB和ΔexsB孢子）。三聚体BclA细丝附着在基底层表面突起上，这些突起似乎是BxpB的三聚体。这些突起与其他基底层蛋白质形成的六方亚基晶体层相互作用。虽然ΔbxpB孢子保留了六角形亚基，但基底层不按结晶顺序组织，缺乏基底层突起和大部分BclA细丝，表明BxpB在外孢子组织中起中心作用。
Bacillus anthracis and other pathogenic Bacillus species form spores that are surrounded by an exosporium, a balloon-like layer that acts as the outer permeability barrier of the spore and contributes to spore survival and virulence. The exosporium consists of a hair-like nap and a paracrystalline basal layer. The filaments of the nap are comprised of trimers of the collagen-like glycoprotein BclA, while the basal layer contains approximately 20 different proteins. One of these proteins, BxpB, forms tight complexes with BclA and is required for attachment of essentially all BclA filaments to the basal layer. Another basal layer protein, ExsB, is required for the stable attachment of the exosporium to the spore. To determine the organization of BclA and BxpB within the exosporium, we used cryo-electron microscopy, cryo-sectioning and crystallographic analysis of negatively stained exosporium fragments to compare wildtype spores and mutant spores lacking BclA, BxpB or ExsB (ΔbclA, ΔbxpB and ΔexsB spores, respectively). The trimeric BclA filaments are attached to basal layer surface protrusions that appear to be trimers of BxpB. The protrusions interact with a crystalline layer of hexagonal subunits formed by other basal layer proteins. Although ΔbxpB spores retain the hexagonal subunits, the basal layer is not organized with crystalline order and lacks basal layer protrusions and most BclA filaments, indicating a central role for BxpB in exosporium organization.
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影响因子：
3.1
作者：
Kang, TJ;Fenton, MJ;Cross, AS
通讯作者：
Cross, AS
影响因子：
3.2
作者：
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Daubenspeck, JM;Zeng, HD;Turnbough, CL
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2.7
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影响因子：
3.4
作者：
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