BB0562 is a nutritional virulence determinant with lipase activity important for Borrelia burgdorferi infection and survival in fatty acid deficient environments.
BB0562 is a nutritional virulence determinant with lipase activity important for Borrelia burgdorferi infection and survival in fatty acid deficient environments.
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DOI：
10.1371/journal.ppat.1009869
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发表时间：
2021-08
期刊：
影响因子：
6.7
通讯作者：
Jewett MW
中科院分区：
文献类型：
--
作者：
Kuhn HW;Lasseter AG;Adams PP;Avile CF;Stone BL;Akins DR;Jewett TJ;Jewett MW
莱姆病螺旋体伯氏疏螺旋体依靠从宿主环境中摄取必需营养素来生存和感染。因此，营养获取机制构成了病原体的关键毒力特性，但这些机制在很大程度上仍然未知。在哺乳动物感染B. burgdorferi （BbIVET）的体内表达技术中鉴定出基因bb0562，该基因编码一个由未知功能保守结构域DUF3996组成的假设蛋白。DUF3996也在相邻编码的假设蛋白BB0563和BB0564中被发现，这表明这三种蛋白可能在功能上相关。bb0562、bb0563和bb0564的缺失表明，单独的bb0562对免疫正常和免疫低下小鼠通过针接种和蜱叮咬传播的最佳播散性感染很重要。此外，bb0562在感染的血液传播阶段促进了螺旋体的存活。bb0562基因也被发现对螺旋体在低血清培养基中的生长很重要，并且通过添加各种长链脂肪酸，特别是油酸，可以挽救Δbb0562伯氏疏螺旋体的生长缺陷。在哺乳动物中，脂肪酸主要以甘油三酯的形式储存在脂肪滴中。引人注目的是，在低血清培养基中添加三油酸甘油酯（油酸的甘油三酯形式）并没有挽救突变体的生长缺陷，这表明bb0562可能对甘油三酯中脂肪酸的释放很重要。因此，我们在BB0562中寻找并鉴定了两个典型的GXSXG脂肪酶基序，尽管与已知的细菌脂肪酶缺乏同源性。纯化的BB0562显示出脂肪分解活性依赖于两个基序内的催化丝氨酸残基。总之，我们已经确定bb0562是一种新的营养毒力决定因素，它编码一种脂肪酶，有助于螺旋体在缺乏游离脂肪酸的环境中存活，包括哺乳动物宿主。伯氏疏螺旋体是莱姆病的病原体，它的基因组很小，缺乏自身合成必需营养物质的能力，也缺乏导致疾病的细菌病原体的许多典型毒力特性。莱姆病的临床表现主要是由于伯氏疏螺旋体感染引起的炎症反应。因此，营养获取功能是病原菌的关键毒力因子。脂肪酸是伯氏疏螺旋体膜和脂蛋白的关键成分，螺旋体必须从宿主环境中清除。此前，通过对哺乳动物感染过程中表达的伯氏疏螺旋体基因的遗传筛选，我们确定了功能未知的基因bb0562。在此，我们证明bb0562编码一种脂肪酶，该酶在甘油三酯释放游离脂肪酸中发挥作用。此外，bb0562有助于伯氏疏螺旋体在哺乳动物宿主中的存活和传播。BB0562对螺旋体在游离脂肪酸含量低的环境中存活很重要，从而增加了伯氏疏螺旋体的营养毒力决定因素库，这些决定因素是维持蜱-小鼠地方性动物循环和引起弥散性疾病所必需的。
The Lyme disease spirochete Borrelia burgdorferi relies on uptake of essential nutrients from its host environments for survival and infection. Therefore, nutrient acquisition mechanisms constitute key virulence properties of the pathogen, yet these mechanisms remain largely unknown. In vivo expression technology applied to B. burgdorferi (BbIVET) during mammalian infection identified gene bb0562, which encodes a hypothetical protein comprised of a conserved domain of unknown function, DUF3996. DUF3996 is also found across adjacent encoded hypothetical proteins BB0563 and BB0564, suggesting the possibility that the three proteins could be functionally related. Deletion of bb0562, bb0563 and bb0564 individually and together demonstrated that bb0562 alone was important for optimal disseminated infection in immunocompetent and immunocompromised mice by needle inoculation and tick bite transmission. Moreover, bb0562 promoted spirochete survival during the blood dissemination phase of infection. Gene bb0562 was also found to be important for spirochete growth in low serum media and the growth defect of Δbb0562 B. burgdorferi was rescued with the addition of various long chain fatty acids, particularly oleic acid. In mammals, fatty acids are primarily stored in fat droplets in the form of triglycerides. Strikingly, addition of glyceryl trioleate, the triglyceride form of oleic acid, to the low serum media did not rescue the growth defect of the mutant, suggesting bb0562 may be important for the release of fatty acids from triglycerides. Therefore, we searched for and identified two canonical GXSXG lipase motifs within BB0562, despite the lack of homology to known bacterial lipases. Purified BB0562 demonstrated lipolytic activity dependent on the catalytic serine residues within the two motifs. In sum, we have established that bb0562 is a novel nutritional virulence determinant, encoding a lipase that contributes to fatty acid scavenge for spirochete survival in environments deficient in free fatty acids including the mammalian host. Borrelia burgdorferi, the causative agent of Lyme disease, has a small genome and lacks the ability to synthesize essential nutrients on its own as well as many of the virulence properties typical of bacterial pathogens that contribute to disease. The clinical manifestations of Lyme disease predominantly result from inflammation in response to the B. burgdorferi infection. Therefore, nutrient acquisition functions constitute key virulence factors for the pathogen. Fatty acids are critical components of B. burgdorferi membranes and lipoproteins, which the spirochete must scavenge from the host environment. Previously, through a genetic screen for B. burgdorferi genes that are expressed during mammalian infection we identified gene of unknown function, bb0562. Herein, we demonstrate that bb0562 encodes a lipase that plays a role in the release of free fatty acids from triglycerides. Furthermore, bb0562 contributes to B. burgdorferi survival and dissemination in the mammalian host. BB0562 is important for spirochete survival in environments low in free fatty acids thereby adding to B. burgdorferi’s arsenal of nutritional virulence determinants necessary for the pathogen to be maintained in the tick-mouse enzootic cycle and to cause disseminated disease.
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影响因子：
6.7
作者：
Crowley JT;Toledo AM;LaRocca TJ;Coleman JL;London E;Benach JL
通讯作者：
Benach JL
影响因子：
5.7
作者：
Adams PP;Flores Avile C;Jewett MW
通讯作者：
Jewett MW
影响因子：
3.2
作者：
BELISLE, JT;BRANDT, ME;NORGARD, MV
通讯作者：
NORGARD, MV
DOI：
10.1007/978-1-4939-7383-5_12
发表时间：
2018-01-01
期刊：
BORRELIA BURGDORFERI: METHODS AND PROTOCOLS
影响因子：
--
作者：
Adams, Philip P.;Jewett, Mollie W.
通讯作者：
Jewett, Mollie W.
影响因子：
14.9
作者：
Adams PP;Flores Avile C;Popitsch N;Bilusic I;Schroeder R;Lybecker M;Jewett MW
通讯作者：
Jewett MW