CAJ | 학술논문

具有分子伴侣和蛋白酶双重活性的大肠杆菌DegP蛋白,在热休克和其他应激条件下,对于降解和清除膜间质中变性或损伤的蛋白质起着十分重要的作用.到目前为止,已有几种蛋白质被鉴定出是DegP的天然底物.以前的研究表明,DegP的体内底物之一,PapG菌毛蛋白的羧基端多肽能够激活DegP的蛋白酶活性.然而这种激活的机制及生理意义均未见报道.用合成的PapG菌毛蛋白的羧基端多肽对这种激活的机制进行了初步研究.结果表明,DegP与多肽结合后发生了可检测的构象变化.圆二色性光谱结果显示,结合多肽后DegP的二级结构和三级结构均发生了一定的变化.凝胶排阻层析和动态光散射实验也揭示出DegP分子在一定程度上变小.进一步实验表明,DegP在多肽存在下,其疏水表面和催化位点均有所暴露.荧光各向异性结果显示出DegP在结合多肽后其构象柔性降低.对上述结果的意义进行了探讨.
구유분자반려화단백매쌍중활성적대장간균DegP단백,재열휴극화기타응격조건하,대우강해화청제막간질중변성혹손상적단백질기착십분중요적작용.도목전위지,이유궤충단백질피감정출시DegP적천연저물.이전적연구표명,DegP적체내저물지일,PapG균모단백적최기단다태능구격활DegP적단백매활성.연이저충격활적궤제급생리의의균미견보도.용합성적PapG균모단백적최기단다태대저충격활적궤제진행료초보연구.결과표명,DegP여다태결합후발생료가검측적구상변화.원이색성광보결과현시,결합다태후DegP적이급결구화삼급결구균발생료일정적변화.응효배조층석화동태광산사실험야게시출DegP분자재일정정도상변소.진일보실험표명,DegP재다태존재하,기소수표면화최화위점균유소폭로.형광각향이성결과현시출DegP재결합다태후기구상유성강저.대상술결과적의의진행료탐토.
The DegP protein, functioning as both chaperone and protease, plays a critical role in degrading and removing denatured or damaged proteins in the cellular envelope during heat shock and other stresses. So far, several proteins have been identified as its natural targets. A carboxyle-terminal peptide derived from the PapG pilus, one of the in vivo substrates for DegP, has been shown to activate the protease. Nevertheless, neither the details nor the physiological implications of such activation have been studied. The evidence that DegP undergoes conformational changes upon binding the peptide derived from C-terminal sequence of pilus subunit PapG has been presented. It demonstrated that upon binding this peptide, detectable changes can be observed for both secondary and tertiary structures of DegP, as examined by CD spectroscopy. Gel filtration and dynamic light scattering analysis also revealed that the size of DegP becomes smaller to a minor extent. Moreover, both the hydrophobic surfaces and catalytic sites of DegP were found to expose slightly in the presence of the peptide. Upon peptide binding, a less flexible and more rigid conformation of DegP was obtained as analyzed by fluorescence anisotropy. The physiological implications of these observations for DegP are discussed.