Identification and characterization of HtsA, a second heme-binding protein made by Streptococcus pyogenes
Identification and characterization of HtsA, a second heme-binding protein made by Streptococcus pyogenes
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DOI：
10.1128/iai.71.10.5962-5969.2003
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发表时间：
2003-10-01
影响因子：
3.1
通讯作者：
Musser, JM
中科院分区：
文献类型：
--
作者：
Lei, BF;Liu, MY;Musser, JM
A 族链球菌 (GAS) 可以使用血红素和血红素蛋白作为铁源。然而，GAS 中获取血红素的机制尚未明确揭示。最近，我们鉴定了一种由 GAS 制备的新型血红素相关细胞表面蛋白 (Shp)。 shp 基因与八个下游基因共转录，包括编码假定的 ABC 转运蛋白（指定为 HtsABC）的间谍1795、间谍1794 和间谍1793。本研究从血清型M1菌株中克隆了spy1795（命名为htsA），重组HtsA在大肠杆菌中过表达并纯化至均质。 HtsA 结合每个蛋白质分子的 I 血红素分子。 HtsA 在体外产生并定位于细菌细胞表面。与补充有 0.2% 酵母提取物的 Todd-Hewitt 肉汤相比，GAS 上调了人血液中 htsA 的转录。与金属阳离子充足的条件下相比，在金属阳离子限制的条件下，htsA转录物的水平显着增加。 HtsA 的阳离子含量、细胞表面位置和基因转录也与 MtsA 和 Spy0385（GAS 的另外两种假定的铁获取 ABC 转运蛋白的脂蛋白成分）进行了比较。我们的结果表明 HtsABC 是一种 ABC 转运蛋白，可能参与 GAS 中血红素的获取。
Group A streptococci (GAS) can use heme and hemoproteins as sources of iron. However, the machinery for heme acquisition in GAS has not been firmly revealed. Recently, we identified a novel heme-associated cell surface protein (Shp) made by GAS. The shp gene is cotranscribed with eight downstream genes, including spy1795, spy1794, and spy1793 encoding a putative ABC transporter (designated HtsABC). In this study, spy1795 (designated htsA) was cloned from a serotype M1 strain, and recombinant HtsA was overexpressed in Escherichia coli and purified to homogeneity. HtsA binds I heme molecule per molecule of protein. HtsA was produced in vitro and localized to the bacterial cell surface. GAS up-regulated transcription of htsA in human blood compared with that in Todd-Hewitt broth supplemented with 0.2% yeast extract. The level of the htsA transcript dramatically increased under metal cation-restricted conditions compared with that under metal cation-replete conditions. The cation content, cell surface location, and gene transcription of HtsA were also compared with those of MtsA and Spy0385, the lipoprotein components of two other putative iron acquisition ABC transporters of GAS. Our results suggest that HtsABC is an ABC transporter that may participate in heme acquisition in GAS.