Conjugative pili of IncP plasmids, and the Ti plasmid T pilus are composed of cyclic subunits
Conjugative pili of IncP plasmids, and the Ti plasmid T pilus are composed of cyclic subunits
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DOI：
10.1074/jbc.274.32.22548
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发表时间：
1999-08-06
影响因子：
4.8
通讯作者：
Lanka, E
中科院分区：
文献类型：
--
作者：
Eisenbrandt, R;Kalkum, M;Lanka, E
TrbC proproin是大肠杆菌中IncP结合丸中匹林亚基TrbC的前体。同样，它的同源物VirB2 propilin在农杆菌中被加工成Ti质粒T pilus的T pilin。TrbC和VirB2 propilin分别在翻译后的N端通过去除一个36/47残基前导肽而被截断。TrbC proproin通过宿主编码功能去除C端27个残基，然后通过质粒携带的丝氨酸蛋白酶去除另外4个C端残基，从而经历第二加工步骤。78个残基的最终产物TrbC通过分子内共价首尾肽键环化。T柱不经历额外的截断，但同样是环化的。这些柱状结构的圆形结构，经质谱验证，代表了新的基本结构，符合并组装成共轭装置。
TrbC propilin is the precursor of the pilin subunit TrbC of IncP conjugative pill in Escherichia coli. Likewise, its homologue, VirB2 propilin, is processed into T pilin of the Ti plasmid T pilus in Agrobacterium tumefaciens. TrbC and VirB2 propilin are truncated post-translationally at the N terminus by the removal of a 36/47-residue leader peptide, respectively. TrbC propilin undergoes a second processing step by the removal of 27 residues at the C terminus by host-encoded functions followed by the excision of four additional C-terminal residues by a plasmid-borne serine protease. The final product TrbC of 78 residues is cyclized via an intramolecular covalent head-to-tail peptide bond. The T pilin does not undergo additional truncation but is likewise cyclized. The circular structures of these pilins, as verified by mass spectrometry, represent novel primary configurations that conform and assemble into the conjugative apparatus.