title: Modulation of the inhibitor properties of dipeptidyl (acyloxy)methyl ketones toward the CaaX proteases.
abstract: Dipeptidyl (acyloxy)methyl ketones (AOMKs) have been identified as mechanism-based inhibitors of certain cysteine proteases. These compounds are also inhibitors of the integral membrane proteins Rce1p and Ste24p, which are proteases that independently mediate a cleavage step associated with the maturation of certain isoprenylated proteins. The enzymatic mechanism of Rce1p is ill-defined, whereas Ste24p is a zinc metalloprotease. Rce1p is required for the proper processing of the oncoprotein Ras and is viewed as a potential target for cancer therapy. In this study, we synthesized a small library of dipeptidyl AOMKs to investigate the structural elements that contribute to the inhibitor properties of this class of molecules toward Rce1p and Ste24p. The compounds were evaluated using a fluorescence-based in vitro proteolysis assay. The most potent dipeptidyl AOMKs contained an arginine residue and the identity of the benzoate group strongly influenced potency. A 'warhead' free AOMK inhibited Rce1p and Ste24p. The data suggest that the dipeptidyl AOMKs are not mechanism-based inhibitors of Rce1p and Ste24p and corroborate the hypothesis that Rce1p is not a cysteine protease.
authors.affiliation: Department of Chemistry, University of Georgia, Athens, GA 30602-2556, USA.
authors.forename: Anne-Marie R
authors.initials: AM
authors.lastname: Dechert
authors.forename: James P
authors.initials: JP
authors.lastname: MacNamara
authors.forename: Sarah R
authors.initials: SR
authors.lastname: Breevoort
authors.forename: Emily R
authors.initials: ER
authors.lastname: Hildebrandt
authors.forename: Ned W
authors.initials: NW
authors.lastname: Hembree
authors.forename: Adam C
authors.initials: AC
authors.lastname: Rea
authors.forename: Duncan E
authors.initials: DE
authors.lastname: McLain
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Porter
authors.forename: Walter K
authors.initials: WK
authors.lastname: Schmidt
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Dore
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology; D057056:Cysteine Proteases / Q000235:genetics / Q000378:metabolism*; D004151:Dipeptides / Q000737:chemistry / Q000494:pharmacology*; D004354:Drug Screening Assays, Antitumor; D007659:Ketones / Q000737:chemistry / Q000494:pharmacology*; D008565:Membrane Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D008666:Metalloendopeptidases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D043484:Proprotein Convertases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D011480:Protease Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D000970:Antineoplastic Agents; D004151:Dipeptides; D007659:Ketones; D008565:Membrane Proteins; D011480:Protease Inhibitors; D029701:Saccharomyces cerevisiae Proteins; D057056:Cysteine Proteases; D043484:Proprotein Convertases; C105193:RCE1 protein, S cerevisiae; D008666:Metalloendopeptidases; C491251:STE24 protein, S cerevisiae