Pilus backbone protein PitB of Streptococcus pneumoniae contains stabilizing intramolecular isopeptide bonds.
Pilus backbone protein PitB of Streptococcus pneumoniae contains stabilizing intramolecular isopeptide bonds.
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肺炎链球菌的菌毛骨架蛋白 PitB 含有稳定的分子内异肽键。
DOI：
10.1016/j.bbrc.2011.05.038
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发表时间：
2011
影响因子：
3.1
通讯作者：
Stephens,DavidS
中科院分区：
文献类型：
--
作者：
Zahner,Dorothea;Gandhi,AshishR;Stuchlik,Olga;Reed,Matthew;Pohl,Jan;Stephens,DavidS
肺炎链球菌2型皮利是最近鉴定的从细菌表面延伸并由结构蛋白PitB的聚合物形成的菌毛结构。分子内异肽键是A组链球菌相关菌毛骨架蛋白Spy 0128的特征。在此基础上，我们预测了PitB中的两个分子内异肽键。采用串联质谱和Edman测序相结合的方法，我们发现这些键形成于PitB中的Lys 63-Asn 214和Lys 243-Asn 372之间。缺乏分子内异肽键的突变蛋白保留了野生型蛋白所观察到的蛋白水解稳定性。然而，这些债券的情况下，大大降低了PitB衍生物的熔融温度，表明这些债券的稳定功能的PitB的肺炎球菌2型菌毛。
Streptococcus pneumoniae type 2 pili are recently identified fimbrial structures extending from the bacterial surface and formed by polymers of the structural protein PitB. Intramolecular isopeptide bonds are a characteristic of the related pilus backbone protein Spy0128 of group A streptococci. Based on the identification of conserved residues in PitB, we predicted two intramolecular isopeptide bonds in PitB. Using a combination of tandem mass spectrometry and Edman sequencing, we show that these bonds were formed between Lys63-Asn214and Lys243-Asn372in PitB. Mutant proteins lacking the intramolecular isopeptide bonds retained the proteolytic stability observed with the wild type protein. However, absence of these bonds substantially decreased the melting temperature of the PitB-derivatives, indicating a stabilizing function of these bonds in PitB of the pneumococcal type 2 pilus.