The N‐terminal prepeptide is required for the production of spore cortex‐lytic enzyme from its inactive precursor during germination of Clostridium perfringens S40 spores
The N‐terminal prepeptide is required for the production of spore cortex‐lytic enzyme from its inactive precursor during germination of Clostridium perfringens S40 spores
复制标题
在产气荚膜梭菌 S40 孢子萌发过程中，N 端前肽是从其无活性前体产生孢子皮质裂解酶所必需的
作者：
S. Okamura;K. Urakami;M. Kimata;T. Aoshima;S. Shimamoto;R. Moriyama;S. Makino
产气荚膜梭菌S40的孢子皮质裂解酶在产孢期合成了一个由四个结构域组成的前体。在萌发过程中，经过N-末端前区和C-末端前区的切割，无活性的酶原(称为C35)在萌发过程中通过处理N-末端的前序列而被转化为活性酶。目前的结果表明，裂解的N-末端前肽仍然与C35有关。分离的复合体在6 M尿素溶液中变性和解离后，去除尿素后重新生成前肽-C35复合体，该复合体与GSP孵育时产生活性酶。然而，单独的C35不能被GSP激活。前肽-C35复合体的热稳定性高于活性酶。因此，需要将前肽以非共价方式连接到C35上，以帮助C35正确折叠并稳定其构象，这表明前肽作为分子内伴侣发挥作用。具有共价结合的前肽的重组蛋白被GSP和体内的前肽-C35复合体处理，需要全长的N末端预测序才能发挥其作用。虽然C-末端前序列是作为一个独立的结构域存在的，它不参与酶的激活过程，但似乎N-末端前序列作为酶的抑制物参与了酶活性的调节。
A spore cortex‐lytic enzyme of Clostridium perfringens S40 is synthesized during sporulation as a precursor consisting of four domains. After cleavage of an N‐terminal preregion and a C‐terminal proregion, inactive proenzyme (termed C35) is converted to active enzyme by processing of an N‐terminal prosequence with germination‐specific protease (GSP) during germination. The present results demonstrated that the cleaved N‐terminal prepeptide remained associated with C35. After the isolated complex was denatured and dissociated in 6 M urea solution, removal of urea regenerated a prepeptide–C35 complex which produces active enzyme when incubated with GSP. However, isolated C35 alone could not be activated by GSP. The prepeptide–C35 complex was more heat stable than active enzyme. Thus, non‐covalent attachment of the prepeptide to C35 is required to assist correct folding of C35 and to stabilize its conformation, suggesting that the prepeptide functions as an intramolecular chaperone. Recombinant proteins, which have prepeptide covalently bonded to C35, were processed by GSP as well as the in vivo prepeptide–C35 complex, and the full length of the N‐terminal presequence was needed to fulfil its role. Although the C‐terminal prosequence is present as an independent domain which is not involved in the activation process of the enzyme, it appears that the N‐terminal prosequence contributes to the regulation of enzyme activity as an inhibitor of the enzyme.
DOI：
10.1016/s0021-9258(18)61070-1
发表时间：
1987-07
期刊：
The Journal of biological chemistry
影响因子：
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作者：
P. Matsudaira
通讯作者：
P. Matsudaira