A novel protein, TtpC, is a required component of the TonB2 complex for specific iron transport in the pathogens Vibrio anguillarum and Vibrio cholerae
A novel protein, TtpC, is a required component of the TonB2 complex for specific iron transport in the pathogens Vibrio anguillarum and Vibrio cholerae
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DOI：
10.1128/jb.00451-06
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发表时间：
2007-03-01
影响因子：
3.2
通讯作者：
Crosa, Jorge H.
中科院分区：
文献类型：
--
作者：
Stork, Michiel;Otto, Ben R.;Crosa, Jorge H.
在革兰氏阴性细菌中，主动运输穿过外膜需要由内膜中的质子动力产生的能量。这种能量通过与蛋白ExbB和ExbD复合的TonB蛋白转导到外膜。在病原体鳗弧菌中，我们已经确定了两个TonB系统，TonB 1和TonB 2，后者用于铁-鳗毒素运输，并转录为操纵子的一部分，该操纵子由orf 2，exbB 2，exbD 2和tonB 2组成。该簇通过在orf 2中插入极性转座子而鉴定，该转座子导致铁-anguibactin运输缺陷的菌株。只有整个簇（orf 2，exbB 2，exbD 2和tonB 2）可以补充铁-anguibactin运输，而只有exbB 2，exbD 2和tonB 2基因不能恢复运输。这表明该Orf 2（命名为TtpC）在鳗弧菌中TonB 2介导的运输中起重要作用。在霍乱弧菌中存在类似的基因簇，即，与ttpC-exbB 2-exbD 2-tonB 2的同源物进行比较，我们证明来自霍乱弧菌的TtpC也在这种人类病原体中TonB 2介导的肠杆菌素转运中发挥作用。此外，我们还表明，在鳗弧菌的TtpC蛋白被发现作为一个复杂的，也可能包含TonB 2，ExbB 2和ExbD 2蛋白的一部分。在鳗弧菌和霍乱弧菌中发现的TonB 2系统的这种新组分可能是携带弧菌样TonB 2系统的细菌的一般特征。
Active transport across the outer membrane in gram-negative bacteria requires the energy that is generated by the proton motive force in the inner membrane. This energy is transduced to the outer membrane by the TonB protein in complex with the proteins ExbB and ExbD. In the pathogen Vibrio anguillarum we have identified two TonB systems, TonB1 and TonB2, the latter is used for ferric-anguibactin transport and is transcribed as part of an operon that consists of orf2, exbB2, exbD2, and tonB2. This cluster was identified by a polar transposon insertion in orf2 that resulted in a strain deficient for ferric-anguibactin transport. Only the entire cluster (orf2, exbB2, exbD2 and tonB2) could complement for ferric-anguibactin transport, while just the exbB2, exbD2, and tonB2 genes were unable to restore transport. This suggests an essential role for this Orf2, designated TtpC, in TonB2-mediated transport in V. anguillarum. A similar gene cluster exists in V. cholerae, i.e., with the homologues of ttpC-exbB2-exbD2-tonB2, and we demonstrate that TtpC from V. cholerae also plays a role in the TonB2-mediated transport of enterobactin in this human pathogen. Furthermore, we also show that in V. anguillarum the TtpC protein is found as part of a complex that might also contain the TonB2, ExbB2, and ExbD2 proteins. This novel component of the TonB2 system found in V. anguillarum and V. cholerae is perhaps a general feature in bacteria harboring the Vibrio-like TonB2 system.