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首页> 外文期刊>Infection and immunity >Identification of a locus involved in the utilization of iron by Haemophilus influenzae.
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Identification of a locus involved in the utilization of iron by Haemophilus influenzae.

机译：鉴定涉及流感嗜血杆菌利用铁的场所。

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Haemophilus influenzae has an absolute requirement for heme for aerobic growth. This organism can satisfy this requirement by synthesizing heme from iron and protoporphyrin IX (PPIX). H. influenzae type b (Hib) strain DL42 was found to be unable to form single colonies when grown on a medium containing free iron and PPIX in place of heme. In contrast, the nontypeable H. influenzae (NTHI) strain TN106 grew readily on the same medium. A genomic library from NTHI strain TN106 was used to transform Hib strain DL42, and recombinants were selected on a medium containing iron and PPIX in place of heme. A recombinant plasmid with an 11.5-kb NTHI DNA insert was shown to confer on Hib strain DL42 the ability to grow on iron and PPIX. Nucleotide sequence analysis revealed that this NTHI DNA insert contained three genes, designated hitA, hitB, and hitC, which encoded products similar to the SfuABC proteins of Serratia marcescens, which have been shown to constitute a periplasmic binding protein-dependent iron transport system in this enteric organism. The NTHI HitA protein also was 69% identical to the ferric-binding protein of Neisseria gonorrhoeae. Inactivation of the cloned NTHI hitC gene by insertion of an antibiotic resistance cartridge eliminated the ability of the recombinant plasmid to complement the growth deficiency of Hib DL42. Construction of an isogenic NTHI TN106 mutant lacking a functional hitC gene revealed that this mutation prevented this strain from growing on a medium containing iron and PPIX in place of heme. This NTHI hitC mutant was also unable to utilize either iron bound to transferrin or iron chelates. These results suggest that the products encoded by the hitABC genes are essential for the utilization of iron by NTHI.
机译：流感嗜血杆菌对血红素有氧生长绝对有要求。这种生物可以通过从铁和原卟啉IX（PPIX）中合成血红素来满足这一要求。当在含有游离铁和PPIX代替血红素的培养基上生长时，发现b型流感嗜血杆菌（Hib）菌株DL42无法形成单个菌落。相反，不可分型的流感嗜血杆菌（NTHI）株TN106在同一培养基上容易生长。使用来自NTHI菌株TN106的基因组文库转化Hib菌株DL42，并在含有铁和PPIX的培养基中选择了重组体，以代替血红素。显示具有11.5kb NTHI DNA插入片段的重组质粒赋予Hib菌株DL42在铁和PPIX上生长的能力。核苷酸序列分析表明，该NTHI DNA插入片段包含三个基因，分别命名为hitA，hitB和hitC，其编码的产物类似于粘质沙雷氏菌的SfuABC蛋白，在该结构中已证明它们构成了周质结合蛋白依赖性铁转运系统。肠有机体。 NTHI HitA蛋白也与淋病奈瑟氏球菌的铁结合蛋白具有69％的同一性。通过插入抗生素抗性盒使克隆的NTHI hitC基因失活，消除了重组质粒补充Hib DL42生长缺陷的能力。缺少功能性hitC基因的等基因NTHI TN106突变体的构建表明，此突变阻止了此菌株在含铁和PPIX的培养基中代替血红素生长。该NTHI hitC突变体也无法利用与运铁蛋白结合的铁或螯合铁。这些结果表明，hitABC基因编码的产物对于NTHI利用铁至关重要。

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