Evidence that two ATP-dependent (Lon) proteases in Borrelia burgdorferi serve different functions.
Evidence that two ATP-dependent (Lon) proteases in Borrelia burgdorferi serve different functions.
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DOI：
10.1371/journal.ppat.1000676
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发表时间：
2009-11
期刊：
影响因子：
6.7
通讯作者：
Benach JL
中科院分区：
文献类型：
--
作者：
Coleman JL;Katona LI;Kuhlow C;Toledo A;Okan NA;Tokarz R;Benach JL
典型的 ATP 依赖性蛋白酶 Lon 参与细菌中的各种生物过程，包括催化受损或衰老的蛋白质以及短命的调节蛋白。疏螺旋体螺旋体的不同寻常之处在于，它们编码两种假定的 ATP 依赖性 Lon 同源物：Lon-1 和 Lon-2。伯氏疏螺旋体是莱姆病的病原体，通过蜱虫的吸血传播。我们实验室之前的工作报告称，伯氏疏螺旋体 lon-1 通过在体外接触血液而转录上调，而 lon-2 则不然。由于 Lon-1 的血液诱导可能在螺旋体传播的毒力因子调节中发挥重要作用，因此阐明这两种蛋白酶在伯氏疏螺旋体中的功能作用是本研究的目的。在染色体上，lon-2 紧邻 ATP 依赖性蛋白酶 clpP 和 clpX 的下游，其排列与大肠杆菌的 lon 相同。系统发育分析表明，由于 NH2 末端底物结合域的差异，Lon-1 和 Lon-2 分别聚类，这可能反映了底物特异性的差异。重组 Lon-1 在体外表现出 ATP 依赖性伴侣蛋白酶的特性，但不补充大肠杆菌 Lon 突变体，而 Lon-2 纠正了两种特征性 Lon 突变体表型。我们得出结论，伯氏疏螺旋体 Lons -1 和 -2 具有不同的功能作用。 Lon-2 的功能与典型的 Lon 一致，参与细胞稳态。 Lon-1凭借其血液诱导作用，并且作为疏螺旋体的独特特征，可能在宿主从节肢动物到温血宿主的适应过程中发挥重要作用。莱姆病由伯氏疏螺旋体螺旋体引起，是北美最流行的节肢动物传播疾病。在自然界中，这种细菌在蜱虫媒介宿主（硬蜱属）和小型啮齿动物（白鼠属）之间摇摆。伯氏疏螺旋体能够通过响应宿主因素或环境线索（例如温度和 pH 值）调节表面脂蛋白或其他蛋白质的表达，在这两种截然不同的宿主环境中持续存在。我们对这一过程的兴趣导致了伯氏疏螺旋体中大肠杆菌 ATP 依赖性 lon 蛋白酶 (lon-1) 的同源物的鉴定，该酶在血液反应中上调。大肠杆菌的原型 Lon 是一种保守的蛋白酶，对于破坏异常和短寿命的蛋白质非常重要。伯氏疏螺旋体的不同寻常之处在于，它还编码第二个 lon 同源物 lon-2，该蛋白在血液反应中不会上调。在本研究中，我们试图阐明 Lon-1 和 Lon-2 在伯氏疏螺旋体中的作用。我们提供的证据表明，Lon-1 是一种 ATP 和 Mg2+ 依赖性蛋白酶，但其功能与原型 Lon 不同。然而，Lon-2 在功能上与大肠杆菌中的 Lon 互补。因此，Lon-1 和 Lon-2 似乎在伯氏疏螺旋体中具有不同的作用。 Lon-1 凭借其血液诱导作用可能对宿主适应很重要，而 Lon-2 是大肠杆菌 Lon 的功能同源物。
The canonical ATP-dependent protease Lon participates in an assortment of biological processes in bacteria, including the catalysis of damaged or senescent proteins and short-lived regulatory proteins. Borrelia spirochetes are unusual in that they code for two putative ATP-dependent Lon homologs, Lon-1 and Lon-2. Borrelia burgdorferi, the etiologic agent of Lyme disease, is transmitted through the blood feeding of Ixodes ticks. Previous work in our laboratory reported that B. burgdorferi lon-1 is upregulated transcriptionally by exposure to blood in vitro, while lon-2 is not. Because blood induction of Lon-1 may be of importance in the regulation of virulence factors critical for spirochete transmission, the clarification of functional roles for these two proteases in B. burgdorferi was the object of this study. On the chromosome, lon-2 is immediately downstream of ATP-dependent proteases clpP and clpX, an arrangement identical to that of lon of Escherichia coli. Phylogenetic analysis revealed that Lon-1 and Lon-2 cluster separately due to differences in the NH2-terminal substrate binding domains that may reflect differences in substrate specificity. Recombinant Lon-1 manifested properties of an ATP-dependent chaperone-protease in vitro but did not complement an E. coli Lon mutant, while Lon-2 corrected two characteristic Lon-mutant phenotypes. We conclude that B. burgdorferi Lons -1 and -2 have distinct functional roles. Lon-2 functions in a manner consistent with canonical Lon, engaged in cellular homeostasis. Lon-1, by virtue of its blood induction, and as a unique feature of the Borreliae, may be important in host adaptation from the arthropod to a warm-blooded host. Lyme disease, caused by the spirochete Borrelia burgdorferi, is the most prevalent arthropod-borne disease in North America. In nature, the bacterium oscillates between its tick vector host (Ixodes spp.) and small rodents (Peromyscus spp.). B. burgdorferi is able to persist in these two very different host environments by modulating the expression of surface lipoproteins proteins, or other proteins, in response to host factors or environmental cues such as temperature and pH. Our interest in this process led to the identification of a homolog of the E. coli ATP-dependent lon protease (lon-1) in B. burgdorferi that was upregulated in response to blood. The prototypical Lon of E. coli is a conserved protease important for the destruction of abnormal and short-lived proteins. B. burgdorferi is unusual in that it also codes for a second lon homolog, lon-2, that was not upregulated in response to blood. In this study, we sought to clarify the roles for Lon-1 and Lon-2 in B. burgdorferi. We present evidence that Lon-1 is an ATP- and Mg2+-dependent protease but does not function in a manner consistent with a prototypical Lon. Lon-2, however, functionally complemented Lon in E. coli. Thus, Lon-1 and Lon-2 appear to have distinct roles in B. burgdorferi; Lon-1 by virtue of its blood induction may be important in host adaptation, while Lon-2 is the functional homolog of E. coli Lon.
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影响因子：
3.1
作者：
de Silva, AM;Zeidner, NS;Fikrig, E
通讯作者：
Fikrig, E
影响因子：
3.1
作者：
COLEMAN, JL;ROGERS, RC;BENACH, JL
通讯作者：
BENACH, JL
影响因子：
64.5
作者：
Coleman, JL;Gebbia, JA;Benach, JL
通讯作者：
Benach, JL
影响因子：
158.5
作者：
BENACH, JL;BOSLER, EM;KASLOW, RA
通讯作者：
KASLOW, RA
影响因子：
3.2
作者：
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通讯作者：
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