Heme utilization in Campylobacter jejuni
Heme utilization in Campylobacter jejuni
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DOI：
10.1128/jb.00994-06
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发表时间：
2006-11-01
影响因子：
3.2
通讯作者：
Ketley, Julian M.
中科院分区：
文献类型：
--
作者：
Ridley, Kristian A.;Rock, Jonathan D.;Ketley, Julian M.
在空肠弯曲菌NCTC 11168中发现了一个由转运基因chuABCD和血红素加氧酶基因Cj1613c组成的铁和毛皮调控的氯化血红素摄取基因簇。chuA或Cj1613c的突变导致在氯化血红素或血红蛋白作为铁的唯一来源的存在下不能生长。chuB、-C或-D的突变仅部分减弱以氯化血红素为唯一铁源的生长，表明C中存在额外的血红素内膜（IM）ABC（ATP结合盒）转运系统。空肠。基因分型实验表明Cj1613c在32株临床分离株中高度保守。一个菌株不具有chuC，但它仍然能够使用氯化血红素/血红蛋白作为唯一的铁源，支持的假设，额外的IM运输基因存在。在另外两个菌株中，基因簇内的序列变异是明显的，可能是观察到的负血红素利用表型的原因。Cj1613c-chuA基因间间隔区内的启动子活性分析揭示chuABCD和Cj1613c从单独的铁抑制启动子表达，并且该区域在凝胶阻滞研究中也特异性结合纯化的重组Fur（Cj）。纯化的重组His（6）-Cj1613c的吸收光谱显示血红素：His（6）-Cj1613c的结合比为1：1。在抗坏血酸作为电子供体的存在下，该复合物被氧化降解，表明Cj1613c基因产物作为血红素加氧酶发挥作用。总之，我们证实了Cj1613c和ChuABCD参与了C.空肠。
A putative iron- and Fur-regulated hemin uptake gene cluster, composed of the transport genes chuABCD and a putative heme oxygenase gene (Cj1613c), has been identified in Campylobacter jejuni NCTC 11168. Mutation of chuA or Cj1613c leads to an inability to grow in the presence of hemin or hemoglobin as a sole source of iron. Mutation of chuB, -C, or -D only partially attenuates growth where hemin is the sole iron source, suggesting that an additional inner membrane (IM) ABC (ATP-binding cassette) transport system(s) for heme is present in C. jejuni. Genotyping experiments revealed that Cj1613c is highly conserved in 32 clinical isolates. One strain did not possess chuC, though it was still capable of using hemin/hemoglobin as a sole iron source, supporting the hypothesis that additional IM transport genes are present. In two other strains, sequence variations within the gene cluster were apparent and may account for an observed negative heme utilization phenotype. Analysis of promoter activity within the Cj1613c-chuA intergenic spacer region revealed chuABCD and Cj1613c are expressed from separate iron-repressed promoters and that this region also specifically binds purified recombinant Fur(Cj) in gel retardation studies. Absorbance spectroscopy of purified recombinant His(6)-Cj1613c revealed a 1:1 heme:His(6)-Cj1613c binding ratio. The complex was oxidatively degraded in the presence of ascorbic acid as the electron donor, indicating that the Cj1613c gene product functions as a heme oxygenase. In conclusion, we confirm the involvement of Cj1613c and ChuABCD in heme/hemoglobin utilization in C. jejuni.