The Multi-Leu peptide inhibitor discriminates between PACE4 and furin and exhibits antiproliferative effects on prostate cancer cells.

The proprotein convertases (PCs) play an important role in protein precursor activation through processing at paired basic residues. However, significant substrate cleavage redundancy has been reported between PCs. The question remains whether specific PC inhibitors can be designed.

Targeting host cell furin proprotein convertases as a therapeutic strategy against bacterial toxins and viral pathogens.

Pathogens or their toxins, including influenza virus, Pseudomonas, and anthrax toxins, require processing by host proprotein convertases (PCs) to enter host cells and to cause disease. Conversely, inhibiting PCs is likely to protect host cells from multiple furin-dependent, but otherwise unrelated, pathogens. To determine if this concept is correct, we designed specific nanomolar inhibitors of PCs modeled from the extended cleavage motif TPQRERRRKKR downward arrowGL of the avian influenza H5N1 hemagglutinin.

Short polybasic peptide sequences are potent inhibitors of PC5/6 and PC7: Use of positional scanning-synthetic peptide combinatorial libraries as a tool for the optimization of inhibitory sequences.

Positional scanning-synthetic peptide combinatorial libraries (PS-SPCLs) are powerful molecular tools to identify enzyme substrate and potent inhibitory sequences and also to provide crucial information about active site determinants. PS-SPCLs have been surveyed for furin, proprotein convertase (PC)2, PC1/3, and PACE4 and proven efficient to identify potent peptidyl inhibitors in the low nanomolar range for furin and PC1/3. We report herein the screenings of nonamidated and acetylated hexapeptide PS-SPCLs for PC5/6A and PC7.

Both PA63 and PA83 are endocytosed within an anthrax protective antigen mixed heptamer: a putative mechanism to overcome a furin deficiency.

Anthrax toxin consists of protective antigen (PA), and lethal (LF) and edema (EF) factors. A 83 kDa PA monomer (PA83) precursor binds to the cell receptor. Furin-like proprotein convertases (PCs) cleave PA83 to generate cell-bound 63 kDa protein (PA63).

Cutting back on pro-protein convertases: the latest approaches to pharmacological inhibition.

The secretory pathway in cells possesses an elaborate set of endoproteolytic enzymes that carry out a crucial step in protein precursor maturation. This step is proteolytic activation by cleavage at specific pairs of basic residues. These enzymes, named pro-protein convertases (PCs), are responsible for generating bioactive peptides and activating several enzymes and growth factors that are implicated in many important physiological events.

TACE/ADAM-17 maturation and activation of sheddase activity require proprotein convertase activity.

Proprotein convertases (PCs) have been proposed to play a role in tumor necrosis factor-alpha converting enzyme (TACE) processing/activation. Using the furin-deficient LoVo cells, as well as the furin-proficient synoviocytes and HT1080 cells expressing the furin inhibitor alpha(1)-PDX, we demonstrate that furin activity alone is not sufficient for effective maturation and activation of the TACE enzyme. Data from in vitro and in vivo cleavage assays indicate that PACE-4, PC5/PC6, PC1 and PC2 can directly cleave the TACE protein and/or peptide.

Optimization of protease-inhibitor interactions by randomizing adventitious contacts.

Polypeptide protease inhibitors are often found to inhibit targets with which they did not coevolve, as in the case of high-affinity inhibition of bacterial subtilisin by the leech inhibitor eglin c. Two kinds of contacts exist in such complexes: (i) reactive site loop-active site contacts and (ii) interactions outside of these that form the broader enzyme-inhibitor interface. We hypothesized that the second class of "adventitious" contacts could be optimized to generate significant increases in affinity for a target enzyme or discrimination of an inhibitor for closely related target proteases.

Furin processing and proteolytic activation of Semliki Forest virus.

The alphavirus Semliki Forest virus (SFV) infects cells via a low-pH-dependent membrane fusion reaction mediated by the E1 envelope protein. Fusion is regulated by the interaction of E1 with the receptor-binding protein E2. E2 is synthesized as a precursor termed "p62," which forms a stable heterodimer with E1 and is processed late in the secretory pathway by a cellular furin-like protease.

Processing of proendothelin-1 by members of the subtilisin-like pro-protein convertase family.

Endothelial cells (ECs) secrete numerous bioactive peptides that are initially synthesized as inactive precursor proteins. One of these, proendothelin-1 (proET-1), undergoes proteolysis at specific pairs of basic amino acids. Here, we wished to examine the role of mammalian convertases in this event.

Inhibitors of the subtilase-like pro-protein convertases (SPCs).

Following protein biosynthesis, some of the most important cellular mechanisms that generate biological diversity are the enzymatically driven post-translational modifications that ultimately lead to the formation of bioactive molecules. Within the secretory pathway, a multitude of precursor proteins are thus modified resulting in hormones, neuropeptides, growth factors, receptors and even enzymes. These modifications include cleavage at specific sites through endo- or exo-peptidase action, amidation, glycosylation and sulfation.

Inhibitory potency and specificity of subtilase-like pro-protein convertase (SPC) prodomains.

The SPCs (subtilisin-like pro-protein convertases) are a family of enzymes responsible for the proteolytic processing of numerous precursor proteins of the constitutive and regulated secretory pathways. SPCs are themselves synthesized as inactive zymogens. Activation of SPCs occurs via the intramolecular autocatalytic removal of the prodomain.