...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of bacteriology >Use of heme reporters for studies of cytochrome biosynthesis and heme transport.
【24h】

Use of heme reporters for studies of cytochrome biosynthesis and heme transport.

机译：使用血红素报告基因研究细胞色素的生物合成和血红素转运。

获取原文
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Strains of Escherichia coli containing mutations in the cydDC genes are defective for synthesis of the heme proteins cytochrome bd and c-type cytochromes. The cydDC genes encode a putative heterodimeric ATP-binding cassette transporter that has been proposed to act as an exporter of heme to the periplasm. To more fully understand the role of this transporter (and other factors) in heme protein biosynthesis, we developed plasmids that produce various heme proteins (e.g., cytochrome b5, cytochrome b562, and hemoglobin) in the periplasm of E. coli. By using these reporters, it was shown that the steady-state levels of polypeptides of heme proteins known to be stable without heme (e.g., cytochrome b5 and hemoglobin apoprotein) are significantly reduced in a cydC mutant. Exogenous addition of hemin to the cydC mutant still resulted in < 10% of wild-type steady-state levels of apohemoglobin in the periplasm. Since the results of heme reporter studies are not consistent with lower heme availability (i.e., heme export) in a cydC mutant, we analyzed other properties of the periplasm in cydC mutants and compared them with those of the periplasm in cydAB (encoding cytochrome bd) mutants and wild-type cells. Our results led us to favor a hypothesis whereby cydDC mutants are defective in the reduction environment within the periplasmic space. Such an imbalance could lead to defects in the synthesis of heme-liganded proteins. The heme reporters were also used to analyze strains of E. coli with a defect in genes encoding homologs of a different ABC transporter (helABC). The helABC genes have previously been shown to be required for the assembly of c-type cytochromes in Rhodobacter capsulatus (R. G. Kranz, J. Bacteriol. 171:456-464, 1989; D. L. Beckman, D. R. Trawick, and R. G. Kranz, Genes Dev. 6:268-283, 1992). This locus was shown to be essential in E. coli for endogenous cytochrome c biogenesis but not cytochrome b562 synthesis. Consistent with these and previous results, it is proposed that the HelABC transporter is specifically involved in heme export for ligation (hel). This class of periplasmic cytochromes is proposed to require heme liganding before undergoing correct folding.
机译：在cydDC基因中含有突变的大肠杆菌菌株对于血红素蛋白细胞色素bd和c型细胞色素的合成是有缺陷的。 cydDC基因编码一个假定的异二聚体ATP结合盒转运蛋白，该转运蛋白已被提议充当血红素向周质的输出。为了更充分地了解这种转运蛋白（和其他因素）在血红素蛋白生物合成中的作用，我们开发了在大肠杆菌的周质中产生各种血红素蛋白（例如细胞色素b5，细胞色素b562和血红蛋白）的质粒。通过使用这些报道基因，表明在cydC突变体中，已知在没有血红素的情况下稳定的血红素蛋白（例如，细胞色素b5和血红蛋白载脂蛋白）的多肽的稳态水平显着降低。向cydC突变体中外源添加血红素仍导致周质中载脂蛋白血红蛋白的野生型稳态水平<10％。由于血红素报告基因的研究结果与cydC突变体中较低的血红素利用率（即血红素输出）不一致，因此我们分析了cydC突变体中周质的其他特性，并将其与cydAB（编码细胞色素bd）中周质的特性进行比较。突变体和野生型细胞。我们的结果使我们支持一个假设，即cydDC突变体在周质空间内的还原环境中存在缺陷。这种不平衡可能导致血红素配体蛋白合成的缺陷。血红素报告基因还被用于分析在编码不同ABC转运蛋白（helABC）的同源物的基因中有缺陷的大肠杆菌菌株。先前已经证明helABC基因是在荚膜红细菌中组装c型细胞色素所必需的（RG Kranz，J.Bacteriol.171：456-464，1989; DL Beckman，DR Trawick和RG Kranz，Genes Dev。 6：268-283，1992）。已显示此基因座在大肠杆菌中对于内源性细胞色素C的生物合成是必不可少的，但对于细胞色素b562的合成则不是。与这些结果和先前的结果一致，提议HelABC转运蛋白专门参与血红素输出以结扎（hel）。提出这类周质细胞色素在进行正确折叠之前需要血红素配体。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号