MOLECULAR AND FUNCTIONAL-CHARACTERIZATION OF THE SALMONELLA-TYPHIMURIUM INVASION GENES INVB AND INVC - HOMOLOGY OF INVC TO THE F0F1 ATPASE FAMILY OF PROTEINS
MOLECULAR AND FUNCTIONAL-CHARACTERIZATION OF THE SALMONELLA-TYPHIMURIUM INVASION GENES INVB AND INVC - HOMOLOGY OF INVC TO THE F0F1 ATPASE FAMILY OF PROTEINS
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DOI：
10.1128/jb.176.15.4501-4510.1994
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发表时间：
1994-08-01
影响因子：
3.2
通讯作者：
GALAN, JE
中科院分区：
文献类型：
--
作者：
EICHELBERG, K;GINOCCHIO, CC;GALAN, JE
进入肠上皮细胞是沙门氏菌感染发病机制中的重要步骤。我们的实验室以前已经确定了一个遗传位点，inv，这是必要的有效进入培养的上皮细胞的鼠伤寒沙门氏菌。我们已经进行了分子和功能分析的invB和invC，两个成员的这个位点。这些基因的核苷酸序列表明，invB和invC编码的多肽分子量为15个氨基酸47 kDa，分别。当这些基因在T7启动子的控制下表达时，观察到具有预测大小的多肽。构建了在这些基因中携带非极性突变的菌株，并在各种测定中检查了它们的表型。invC中的突变使S。鼠伤寒沙门氏菌缺陷的能力，进入培养的上皮细胞，而invB的突变没有。将InvB和InvC的预测序列与GenBank中的翻译序列进行比较，发现它们与志贺氏菌的InvB和InvC多肽序列相似。蛋白Spa15和Spa47，它们参与这些生物体的入侵蛋白抗原（Ipa）的表面呈递。此外，InvC显示出与来自许多微生物的F0F1 ATP酶的催化β亚基共享序列同源性的蛋白质家族的显著相似性。与这一发现相一致，纯化的InvC制剂显示出显着的ATP酶活性。定点突变该家族蛋白质催化功能所必需的残基，导致蛋白质缺乏ATP酶活性并且不能补充S的invC突变体。鼠伤寒。这些结果表明，InvC可以激励蛋白质输出装置编码的inv基因座所需的表面呈现的决定因素，需要沙门氏菌进入哺乳动物细胞。InvB在这一过程中的作用仍然不确定。
Entry into intestinal epithelial cells is an essential step in the pathogenesis of Salmonella infections. Our laboratory has previously identified a genetic locus, inv, that is necessary for efficient entry of Salmonella typhimurium into cultured epithelial cells. We have carried out a molecular and functional analysis of invB and invC, two members of this locus. The nucleotide sequence of these genes indicated that invB and invC encode polypeptides with molecular masses of 15 acid 47 kDa, respectively. Polypeptides with the predicted sizes were observed when these genes were expressed under the control of a T7 promoter. Strains carrying nonpolar mutations in these genes were constructed, and their phenotypes were examined in a variety of assays. A mutation in invC rendered S. typhimurium defective in their ability to enter cultured epithelial cells, while mutations in invB did not. Comparison of the predicted sequences of InvB and InvC with translated sequences in GenBank revealed that these polypeptides are similar to the Shigella spp. proteins Spa15 and Spa47, which are involved in the surface presentation of the invasion protein antigens (Ipa) of these organisms. In addition, InvC showed significant similarity to a protein family which shares sequence homology with the catalytic beta subunit of the F0F1 ATPase from a number of microorganisms. Consistent with this finding, purified preparations of InvC showed significant ATPase activity. Site-directed mutagenesis of a residue essential for the catalytical function of this family of proteins resulted in a protein devoid of ATPase activity and unable to complement an invC mutant of S. typhimurium. These results suggest that InvC may energize the protein export apparatus encoded in the inv locus which is required for the surface presentation of determinants needed for the entry of Salmonella species into mammalian cells. The role of InvB in this process remains uncertain.