Protein Unfolding by Peptidylarginine Deiminase

作者：Edit Tarcsa, Lyuben N. Marekov, Giampiero Mei, Gerry Melino, Seung‐Chul Lee, Peter M. Steinert · 发表于：Journal of Biological Chemistry · 年份：1996 · DOI：10.1074/jbc.271.48.30709 · 被引用次数：352 · 研究领域：Signaling Pathways in Disease、Antimicrobial Resistance in Staphylococcus、Peptidase Inhibition and Analysis

Peptidylarginine deiminases, which are commonly found in mammalian cells, catalyze the deimination of protein-bound arginine residues to citrullines. However, very little is known about their substrate requirements and the significance or consequences of this postsynthetic modification. We have explored this reaction in vitro with two known substrates filaggrin and trichohyalin. First, the degree and rate of modification of arginines to citrullines directly correlates with the structural order of the substrate. In filaggrin, which has little structural order, the reaction proceeded rapidly to >95% completion. However, in the highly alpha-helical protein trichohyalin, the reaction proceeded slowly to about 25% and could be forced to a maximum of about 65%. Second, the rate and degree of modification depends on the sequence location of the target arginines. Third, we show by gel electrophoresis, circular dichroism, and fluorescence spectroscopy that the reaction interferes with organized protein structure: the net formation of >/=10% citrulline results in protein denaturation. Cyanate modification of the lysines in model alpha-helix-rich proteins to homocitrullines also results in loss of organized structure. These data suggest that the ureido group on the citrulline formed by the peptidylarginine deiminase enzyme modification functions to unfold proteins due to decrease in net charge, loss of potential ionic bonds, and interference with H bonds.