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首页> 外文期刊>Infection and immunity >Expression of the CopB outer membrane protein by Moraxella catarrhalis is regulated by iron and affects iron acquisition from transferrin and lactoferrin.
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Expression of the CopB outer membrane protein by Moraxella catarrhalis is regulated by iron and affects iron acquisition from transferrin and lactoferrin.

机译：卡他莫拉氏菌对CopB外膜蛋白的表达受铁的调节，并影响铁从转铁蛋白和乳铁蛋白的获取。

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摘要

The amino acid sequence of the cell-surface-exposed, 81-kDa CopB outer membrane protein of Moraxella catarrhalis was found to be similar to those of TonB-dependent outer membrane proteins of other gram-negative bacteria. Expression of CopB was affected by the availability of iron in the growth medium, and the extent of overexpression of CopB in response to iron limitation varied widely among the M. catarrhalis strains tested. Wild-type M. catarrhalis strains were found to be able to utilize ferric citrate, transferrin, lactoferrin, and heme as sources of iron for growth in vitro. However, an isogenic copB mutant was severely impaired in its ability to utilize transferrin and lactoferrin as sole sources of iron for growth, whereas this same mutant grew similarly to the wild-type parent strain when supplied with ferric citrate as the iron source. The copB mutant was not significantly different from its wild-type parent strain in its ability to bind transferrin and lactoferrin. In addition, the wild-type parent strain and the copB mutant exhibited equivalent rates of uptake of 55Fe from ferric citrate. However, the copB mutant was markedly less able than the wild-type strain to take up 55Fe from transferrin and lactoferrin. These results indicate that lack of expression of the CopB protein exerts a direct or indirect effect on the ability of M. catarrhalis to utilize iron bound to certain carrier proteins.
机译：发现粘膜莫拉氏菌的细胞表面暴露的81 kDa CopB外膜蛋白的氨基酸序列与其他革兰氏阴性细菌的TonB依赖性外膜蛋白的氨基酸序列相似。 CopB的表达受到生长培养基中铁的可用性的影响，并且在测试的粘膜炎莫拉氏菌菌株中，响应于铁限制的CopB过度表达的程度差异很大。发现野生型卡他莫拉氏菌菌株能够利用柠檬酸铁，转铁蛋白，乳铁蛋白和血红素作为铁源在体外生长。然而，同基因copB突变体利用运铁蛋白和乳铁蛋白作为唯一的铁源生长的能力严重受损，而当提供柠檬酸铁作为铁源时，该突变体的生长与野生型亲本菌株相似。 copB突变体在结合运铁蛋白和乳铁蛋白的能力上与野生型亲本菌株没有显着差异。另外，野生型亲本菌株和copB突变体表现出从柠檬酸铁吸收55Fe的相等速率。但是，copB突变体从转铁蛋白和乳铁蛋白中摄取55Fe的能力明显低于野生型菌株。这些结果表明，CopB蛋白表达的缺乏对粘膜炎莫拉氏菌利用结合至某些载体蛋白的铁的能力产生了直接或间接的影响。

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