Insights into the mechanism of streptonigrin-induced protein arginine deiminase inactivation

Abstract

Protein citrullination is just one of more than 200 known PTMs. This modification, catalyzed by the Protein Arginine Deiminases (PADs 1–4 and PAD6 in humans), converts the positively charged guanidinium group of an arginine residue into a neutral ureido-group. Given the strong links between dysregulated PAD activity and human disease, we initiated a program to develop PAD inhibitors as potential therapeutics for these and other diseases in which the PADs are thought to play a role. Streptonigrin which possesses both anti-tumor and anti-bacterial activity was later identified as a highly potent PAD4 inhibitor. In an effort to understand why streptonigrin is such a potent and selective PAD4 inhibitor, we explored its structure-activity relationships by examining the inhibitory effects of several analogues that mimic the A, B, C, and/or D rings of streptonigrin. We report the identification of the 7-amino-quinoline-5,8-dione core of streptonigrin as a highly potent pharmacophore that acts as a pan-PAD inhibitor.

Peptidyl arginine deiminase-4 activation exacerbates kidney ischemia-reperfusion injury

“…After demonstrating selective induction of PAD4 expression and increased PAD4 activity after renal I/R, we tested whether PAD4 inhibition would protect against ischemic AKI in mice. We used two distinct inhibitors of PAD: 2-chloroamidine and streptonigrin (6,7). Plasma creatinine values were similar between vehicle-treated and 2-chloroamidine-treated shamoperated mice (anesthesia, laparotomy, right nephrectomy, and recovery; Fig.…”

“…The body temperature was maintained between 36 and 38°C using a surgical heating pad during and after surgery. To test whether PAD4 inhibition protects against renal I/R injury, some mice were pretreated with 2-chloroamidine (100 mg/kg, a specific PAD inhibitor, EMD Millipore, Darmstadt, Germany) or with streptonigrin (0.4 mg/kg, a selective PAD4 inhibitor, Sigma Chemicals, St. Louis, MO) 15 min before the induction of 30 min of renal ischemia (6,7). To test whether PAD4 supplementation exacerbates renal I/R injury, separate cohorts of mice were pretreated with 10 g iv recombinant human PAD4 (rPAD4, Cayman Chemical, Ann Arbor, MI) 15 min before the induction of 20 min of renal ischemia.…”

Development of Activity-Based Proteomic Probes for Protein Citrullination

“…Interaction with R639 was looked upon as key for selectivity against PAD4 as this residue is unique to this isozyme. From a fluorescence polarization activity-based high-throughput screen (HTS), assay streptonigrin ( 3 ) was also found to be a selective inhibitor of PAD4 (Dreyton et al 2014a; Knuckley et al 2010c). …”

A Direct Interaction Between Mitochondrial Proteins and Amyloid-β Peptide and its Significance for the Progression and Treatment of Alzheimer’s Disease

“…TDFA, streptonigrin; Fig. 12; Table 8) [143,144] have been discovered, however, a specific inhibitor of PAD2 has not yet been identified. …”