Tautomycetin Synthetic Analogues: Selective Inhibitors of Protein Phosphatase I

Abstract

Ser/Thr protein phosphatases (PPs) regulate a substantial range of cellular processes with protein phosphatases 1 (PP1) and 2 A (PP2A) accounting for over 90 % of the activity within cells. Nevertheless, tools to study PPs are limited as PPs inhibitors, particularly those selective for PP1 inhibition, are relatively scarce. Two examples of PP1‐selective inhibitors, which share structural similarities, are tautomycin (TTM) and tautomycetin (TTN). This work describes the development of PP1/PP2A inhibitors that incorporate key structural features of TTM and TTN and are designed to conserve regions known to bind the active site of PP1/PP2A but vary regions that differentially contact the hydrophobic groove of PP1/PP2A. In all 28 TTN analogues were synthetically generated that inhibit PP1/PP2A activity at <250 mM; seven possessed inhibition activity at 100 nM. The IC50 values were determined for the seven most active analogues, which ranged from 34 to 1500 nM (PP1) and 70 to 6800 nM (PP2A). Four of the seven analogues possessed PP1 selectivity, and one demonstrated eightfold selectivity in the nanomolar range (PP1 IC50=34 nM, PP2A IC50=270 nM). A rationale is given for the observed differences in selectivity.

PP2Acα-B′/PR61 Holoenzyme of Toxoplasma gondii Is Required for the Amylopectin Metabolism and Proliferation of Tachyzoites

“…3G ). These results clearly showed that PP2Acα plays an essential role in the virulence of T. gondii in mice, which may be related to the inhibition of extensive dephosphorylation ( 4 ), resulting in decreases in the abilities of invasion and proliferation.…”

“…For instance, in contrast to them being only about 30% of the protein phosphatases in humans, serine/threonine (Ser/Thr) phosphatases account for approximately 80% of the protein phosphatome of Toxoplasma gondii , which is the most successful intracellular protozoan parasite, affecting almost all warm blooded animals and one-third world population ( 2 , 3 ). Ser/Thr phosphatase activities are mostly accomplished by protein phosphatase 1 (PP1) and protein phosphatase 2A (PP2A) in many eukaryotes, and these enzymes catalyze more than 90% of Ser/Thr phosphorylated protein reactions ( 4 ). However, although great efforts have been made toward elucidating the roles of Ser/Thr phosphatases in T. gondii and in other apicomplexan parasites ( 5 , 6 ), there is still a lack of comprehensive functional information on PP1 and PP2A in these important pathogens.…”

PP1, PP2A and PP2B Interplay in the Regulation of Sperm Motility: Lessons from Protein Phosphatase Inhibitors

“…The identification of naturally occurring small toxins capable of specifically inhibit PPs, largely contributed to the comprehension of Ser/Thr PPs role in various cellular events and other phosphorylation-dependent processes [ 12 , 13 , 14 ]. In fact, PPs are some of the most catalytically efficient enzymes, as they contain highly conserved active sites and do not possess high substrate specificity, which makes them very susceptible to inhibition by natural toxins [ 72 , 73 ]. Although most PP inhibitors present distinct chemical identities, they usually interact with a similar set of amino acids, along with the two metal ions they coordinate, that collectively compose the PP’s active site [ 12 , 74 ].…”

Deciphering the Role of Protein Phosphatases in Apicomplexa: The Future of Innovative Therapeutics?

“…Over the last decade, there has been a particular interest and rebound in targeting the catalytic subunit of PP1 alone or as a holoenzyme. Given the low probability to develop a selective lead or drug acting against PP1 because of the high conservation of its active site within its family and across species, we and others examined strategies aiming to target PP1 regulatory sub-units to interrupt the formation of PP1 holoenzymes [ 56 , 58 , 61 , 121 , 131 , 132 , 133 ]. The feasibility of those strategies was supported by several studies carried out on viruses showing that the use of small molecules designed to bind to the non-catalytic RVxF binding site of PP1 [ 134 ] was able to prevent viral replication in vitro of viruses such as HIV1 and Ebola [ 135 , 136 , 137 ].…”