Cleavage of preflagellins by an aspartic acid signal peptidase is essential for flagellation in the archaeon Methanococcus voltae
Cleavage of preflagellins by an aspartic acid signal peptidase is essential for flagellation in the archaeon Methanococcus voltae
复制标题
DOI：
10.1046/j.1365-2958.2003.03758.x
复制
发表时间：
2003-11-01
影响因子：
3.6
通讯作者：
Jarrell, KF
中科院分区：
文献类型：
--
作者：
Bardy, SL;Jarrell, KF
随着对古细菌结构研究的深入，古细菌和细菌鞭毛之间的差异越来越明显。一个关键的区别是古细菌前鞭毛蛋白的前导肽的存在，这是从鞭毛蛋白之前，其纳入鞭毛丝。负责去除鞭毛蛋白前导肽的酶被鉴定为FlaK。当在大肠杆菌中表达并用于体外测定时，甲烷球菌的FlaK保留了其前鞭毛蛋白肽酶活性。将整合载体同源重组到flaK的染色体拷贝中导致非运动的、非鞭毛化的表型。突变体的鞭毛蛋白具有较大的分子量比野生型对应物，如预期的，如果他们保留其11- 12-氨基酸的前导肽。在体外试验中，flaK突变体的膜不能处理前鞭毛蛋白。定点突变表明，两个天冬氨酸残基保守的IV型prepilin肽酶是必要的正确识别或加工的preflagellin。由于细菌鞭毛蛋白缺乏前导肽，并且输出和组装不需要肽酶，因此对FlaK的需要进一步强调了古细菌鞭毛与IV型皮利而不是细菌鞭毛的相似性。
The differences between archaeal and bacterial flagella are becoming more apparent as research on the archaeal structure progresses. One crucial difference is the presence of a leader peptide on archaeal preflagellins, which is removed from the flagellin prior to its incorporation into the flagellar filament. The enzyme responsible for the removal of the flagellin leader peptide was identified as FlaK. FlaK of Methanococcus voltae retains its preflagellin peptidase activity when expressed in Escherichia coli and used in an in vitro assay. Homologous recombination of an integration vector into the chromosomal copy of flaK resulted in a non-motile, non-flagellated phenotype. The flagellins of the mutant had larger molecular weights than their wild-type counterparts, as expected if they retained their 11- to 12-amino-acid leader peptide. Membranes of the flaK mutant were unable to process preflagellin in the in vitro assay. Site-directed mutagenesis demonstrated that two aspartic acid residues conserved with ones in type IV prepilin peptidases were necessary for proper recognition or processing of the preflagellin. As bacterial flagellins lack a leader peptide and a peptidase is not required for export and assembly, the requirement for FlaK further emphasizes the similarity archaeal flagella have with type IV pili, rather than with bacterial flagella.