Determinants of organelle-specific activation of Proprotein Convertase 1

描述（由申请人提供）：前蛋白转化酶（PC），如PC 1和弗林蛋白酶，是进化上保守的丝氨酸蛋白酶的普遍存在的超家族，负责介导多种加工步骤以在细胞内产生活性蛋白和肽。由于过早的蛋白酶活性可导致不适当的蛋白质活化、分选或降解，因此PC活性受到N-末端前肽的严格调节，所述N-末端前肽作为分子内伴侣（IMC）起作用以最初折叠蛋白酶结构域，并作为催化抑制剂。尽管它们具有重叠的特异性，但IMC能够作为其同源催化结构域的抑制剂，指导细胞器特异性和pH特异性激活 PC 1和弗林蛋白酶，使他们能够选择性地切割其底物在特定的方式在体内隔室。PC 1和弗林蛋白酶的IMC突变是一系列内分泌疾病中观察到的异常活动的基础，包括极度肥胖、葡萄糖稳态异常以及癌症和心脏病。尽管破坏性的后果细胞内稳态，调节PC的激活的分子和细胞的决定因素知之甚少。利用一系列生物化学、生物物理学、计算和分子技术，本提案的目标是1）确定PC 1的IMC如何作为pH传感器，以及2）开发PC 1活性的特异性抑制剂。

DESCRIPTION (provided by applicant): Proprotein convertases (PCs), such as PC1 and furin, are a ubiquitous super-family of evolutionarily conserved serine proteases responsible for mediating a diverse range of processing steps to generate active proteins and peptides within the cell. As premature protease activity can lead to inappropriate protein activation, sorting, or degradation, PC activity is stringently modulated by N-terminal propeptides that function as Intramolecular Chaperones (IMCs) to initially fold protease domains, and act as catalytic inhibitors. Although they share overlapping specificity, it is the ability of the IMC to act as an inhibitor of its cognate catalytic domain that directs the organelle- and pH-specific activation of PC1 and furin, allowing them to selectively cleave their substrates in compartment-specific manner in vivo. Mutations in IMCs of PC1 and furin underlie the aberrant activities seen in a range of endocrinopathies, including extreme obesity, abnormal glucose homeostasis, as well as cancer and heart disease. Despite devastating consequences on cellular homeostasis, the molecular and cellular determinants that modulate activation of PCs are poorly understood. Using an array of biochemical, biophysical, computational and molecular techniques, the goals of this proposal are to 1) determine how the IMC of PC1 acts as a pH sensor, and 2) develop specific inhibitors of PC1 activity.