识别的周质的cobalamin-binding蛋白质BtuF大肠杆菌。
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科斯特上磨蹭很久N, Bradbeer C, Reeger-Schneider E, W,莫汉蒂AK,维纳MC, Kadner RJ
识别的周质的cobalamin-binding蛋白质BtuF大肠杆菌。
J Bacteriol。2002年2月,184(3):706 - 17所示。
- PubMed ID
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11790740 (在PubMed]
- 文摘
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大肠杆菌细胞吸收维生素B (12) (cyano-cobalamin [CN-Cbl])和铁螯合物利用连续的主动运输过程。运输的CN-Cbl外膜及其在周质是由积累TonB-dependent运输车BtuB。运输穿过细胞质膜(CM)需要BtuC和BtuD蛋白质,这是最相关的跨膜和磷酸腺苷盒式蛋白质序列周质的通透酶iron-siderophore运输。不像大多数的基因组织周质的通透酶,一个候选基因周质的Cbl-binding蛋白质不是btuCED操纵子有关。开放阅读框称为yadT大肠杆菌基因组序列相关的序列为iron-siderophore周质的绑定蛋白复合物和以前涉及CN-Cbl吸收沙门氏菌。重命名BtuF大肠杆菌yadT产品,这里显示参与CN-Cbl吸收。BtuF蛋白表达与c端(6)标签,被证明是转移到周质伴随切除信号序列。CN-Cbl-binding化验使用放射性标记的底物或等温滴定量热法表明,纯化BtuF结合CN-Cbl大约15海里的结合常数。btuF零突变,但不是在侧翼基因pfs和雅,强烈CN-Cbl利用率和减少运输到细胞质中。CN-Cbl btuF突变体的生长反应强于btuC轻微损伤前所述,btuD或btuF突变体。 Hence, null mutations in btuC and btuD were constructed and revealed that the btuC mutant had a strong impairment similar to that of the btuF mutant, whereas the btuD defect was less pronounced. All mutants with defective transport across the CM gave rise to frequent suppressor variants which were able to respond at lower levels of CN-Cbl but were still defective in transport across the CM. These results finally establish the identity of the periplasmic binding protein for Cbl uptake, which is one of few cases where the components of a periplasmic permease are genetically separated.