Determinants of organelle-specific activation of Proprotein Convertase 1

描述(申请人提供)：原蛋白转换酶(PC)，如PC1和Furin，是普遍存在的进化保守的丝氨酸蛋白酶超家族，负责调节一系列不同的加工步骤，在细胞内产生活性蛋白质和多肽。由于过早的蛋白酶活性可能导致蛋白质的不适当激活、分类或降解，PC的活性受到N-末端前肽的严格调节，这些前肽作为分子内伴侣(IMCs)最初折叠蛋白酶域，并作为催化抑制物。尽管它们有重叠的特异性，但它是IMC作为其同源催化结构域的抑制物的能力，指导细胞器和pH特异性的激活 PC1和呋喃，允许它们在体内以隔室特有的方式选择性地切割其底物。PC1和Furin IMCs的突变是一系列内分泌疾病异常活动的基础，包括极端肥胖、葡萄糖稳态异常以及癌症和心脏病。尽管对细胞动态平衡造成了毁灭性的后果，但调节PC激活的分子和细胞决定因素却知之甚少。利用一系列生化、生物物理、计算和分子技术，这项建议的目标是1)确定PC1的IMC如何作为pH传感器，以及2)开发PC1活性的特定抑制剂。

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.