Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2018 Apr;53(2):157-174.
doi: 10.1080/10409238.2018.1431606. Epub 2018 Feb 9.

Rce1: mechanism and inhibition

Shahienaz E Hampton  1 , Timothy M Dore  1   2 , Walter K Schmidt  3
Affiliations
Review

Rce1: mechanism and inhibition

Shahienaz E Hampton et al. Crit Rev Biochem Mol Biol. 2018 Apr.

Abstract

Ras converting enzyme 1 (Rce1) is an integral membrane endoprotease localized to the endoplasmic reticulum that mediates the cleavage of the carboxyl-terminal three amino acids from CaaX proteins, whose members play important roles in cell signaling processes. Examples include the Ras family of small GTPases, the γ-subunit of heterotrimeric GTPases, nuclear lamins, and protein kinases and phosphatases. CaaX proteins, especially Ras, have been implicated in cancer, and understanding the post-translational modifications of CaaX proteins would provide insight into their biological function and regulation. Many proteolytic mechanisms have been proposed for Rce1, but sequence alignment, mutational studies, topology, and recent crystallographic data point to a novel mechanism involving a glutamate-activated water and an oxyanion hole. Studies using in vivo and in vitro reporters of Rce1 activity have revealed that the enzyme cleaves only prenylated substrates and the identity of the a2 amino residue in the Ca1a2X sequence is most critical for recognition, preferring Ile, Leu, or Val. Substrate mimetics can be somewhat effective inhibitors of Rce1 in vitro. Small-molecule inhibitor discovery is currently limited by the lack of structural information on a eukaryotic enzyme, but a set of 8-hydroxyquinoline derivatives has demonstrated an ability to mislocalize all three mammalian Ras isoforms, giving optimism that potent, selective inhibitors might be developed. Much remains to be discovered regarding cleavage specificity, the impact of chemical inhibition, and the potential of Rce1 as a therapeutic target, not only for cancer, but also for other diseases.

Keywords: CaaX proteins; Ras; Ras converting enzyme; cancer; proteases.

PubMed Disclaimer

Conflict of interest statement

Disclosure statement

The authors report no conflicts of interest.

Figures

Figure 1
Figure 1
Overview of post-translational modifications associated with CaaX proteins. Both farnesyl (C15) and geranylgeranyl (C20) can be added to CaaX proteins. There are multiple classes of isoprenylated CaaX proteins: those with motifs that resist cleavage (shunt), those with motifs that are cleaved (canonical), and those additionally modified by cleavage (a-factor) or S-acylation. Motifs shown are for indicated yeast (Ydj1p, Ste18p, a-factor) or human proteins (all others).
Figure 2
Figure 2
Postulated topology models of Rce1. (A) Topology with 8 transmembrane helices found in MmRce1 crystal structure and predicted for HsRce1; (B) 7 transmembrane helices predicted for ScRce1; and (C) Proposed alternative topology for ScRce1 based on substituted cysteine accessibility experiments. Conserved catalytic glutamate and histidine residues are located on blue-colored helices. (see color version of this figure at www.tandfonline.com/ibmg).
Figure 3
Figure 3
Crystal structure of MmRce1 (PDB: 4CAD). The protein structure is oriented with the cytosolic face at the top and that of the ER lumen on the bottom of the image. (see color version of this figure at www.tandfonline.com/ibmg).
Figure 4
Figure 4
Crystal structure of the MmRce1 catalytic site (PDB: 4CAD), showing the locations of the critical residues E140, E141, R145, H173, H227, and N231. Selected N–O distances between residues are given in Ångströms and marked by black dashed lines. The hydrogen bond between H227 and N231 reported by Manolaridis et al. is shown as a yellow line. (see color version of this figure at www.tandfonline.com/ibmg).
Figure 5
Figure 5
Proposed basic catalytic mechanism of MmRce1 proteolysis.
Figure 6
Figure 6
Weblogo amino acid frequency analysis of sequences identified by a Ras-based strategy (Stein et al. 2015). The sequences analyzed were part of a set of sequences (n = 496) having an enrichment score greater than 3, which is suggestive of prenylation. The average enrichment score of the full 8,000 sequence set was 0.80, whereas the average score of the sequences analyzed for frequency analysis was 9.42. Color scheme: Cys is blue; polar charged amino acids are green (Asp, Arg, Glu, His, and Lys); polar uncharged residues are black (Asn, Gln, Ser, Thr, and Tyr); branched chain amino acids are red (Ile, Leu, and Val); and all other residues are purple (Ala, Gly, Met, Phe, Pro, and Trp). (see color version of this figure at www.tandfonline.com/ibmg).
Figure 7
Figure 7
Structures of general protease inhibitors of Rce1.
Figure 8
Figure 8
Structures of selected halo and acyloxymethyl ketone inhibitors of Rce1.
Figure 9
Figure 9
Structures of RPI, SA, and selected RPI analogs.
Figure 10
Figure 10
Structures of peptidomimetic inhibitors.
Figure 11
Figure 11
Structures of natural product inhibitors of Rce1.
Figure 12
Figure 12
Selected examples of Rce1 inhibitors identified in a medium throughput screen.
Figure 13
Figure 13
Examples of NSC1011 derivatives that remained active against HsRce1. Numbers in parentheses are IC50 values or the percent activity of Rce1 after 10 µM treatment as judged using the Rce1 IQF in vitro proteolysis assay (Mohammed et al. 2016). (see color version of this figure at www.tandfonline.com/ibmg).
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Baell JB. Feeling nature’s PAINS: natural products, natural product drugs, and pan assay interference compounds (PAINS) J Nat Prod. 2016;79:616–628. - PubMed
    1. Baell JB, Ferrins L, Falk H, Nikolakopoulos G. PAINS: relevance to tool compound discovery and fragment-based screening. Aust J Chem. 2013;66:1483–1494.
    1. Baell JB, Holloway GA. New substructure filters for removal of pan assay interference compounds (PAINS) from screening libraries and for their exclusion in bioassays. J Med Chem. 2010;53:2719–2740. - PubMed
    1. Baell JB, Walters MA. Chemistry: chemical con artists foil drug discovery. Nature. 2014;513:481–483. - PubMed
    1. Baker RP, Young K, Feng L, Shi Y, Urban S. Enzymatic analysis of a rhomboid intramembrane protease implicates transmembrane helix 5 as the lateral substrate gate. Proc Natl Acad Sci USA. 2007;104:8257–8262. - PMC - PubMed

Publication types

MeSH terms

LinkOut - more resources