Restoration of Proper Trafficking to the Cell Surface for Membrane Proteins Harboring Cysteine Mutations

Abstract

A common phenotype for many genetic diseases is that the cell is unable to deliver full-length membrane proteins to the cell surface. For some forms of autism, hereditary spherocytosis and color blindness, the culprits are single point mutations to cysteine. We have studied two inheritable cysteine mutants of cyclic nucleotide-gated channels that produce achromatopsia, a common form of severe color blindness. By taking advantage of the reactivity of cysteine’s sulfhydryl group, we modified these mutants with chemical reagents that attach moieties with similar chemistries to the wild-type amino acids’ side chains. We show that these modifications restored proper delivery to the cell membrane. Once there, the channels exhibited normal functional properties. This strategy might provide a unique opportunity to assess the chemical nature of membrane protein traffic problems.

Identification ofCNGA3Mutations in 46 Families

“…Previously, CNGA3 mutations had been reported in 81 families, including 76 families with total color blindness (or achromatopsia), 13,15,16,[27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] three families with progressive COD, 13,16 a family with LCA, 17 and a family with oligocone trichromacy 44 according to information from an online database (HGMD Professional [https://portal.biobase-international .com/hgmd/pro/gene.php?gene=CNGA3]). One study 16 also indicated that CNGA3 mutations detected in achromatopsia were also present in patients with CORDs.…”

“…In summary, an online database (HGMD Professional) reports 81 CNGA3 mutations, including 69 missense, 13,[15][16][17][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] eight nonsense, 16,27,29 three small insertion, 16,27 and a small deletion. 16 In the present study, 39 CNGA3 variants were detected, including 26 novel and 13 known mutations.…”

Assistance for Folding of Disease-Causing Plasma Membrane Proteins

“…Glycosylation often starts while MP is translocated into the ER, and a preassembled polymannose oligosaccharide is transferred to the luminal N-aminoacidic residue of the classic motif including asparagine-X-serine/threonine(N-X-S/T) as a consensus sequence. Once in the Golgi, some enzymatic reactions can add sugar moieties or just modify the preexisting glycan tree complexity [121][122][123].…”

“…Glycerol [312]. MTSHB (Hydroxybenzyl-Methanethiosulfonate), MTSEA (Aminoethyl-Methanethiosulfonate) [123].…”

Grafting synthetic transmembrane units to the engineered low-toxicity α-hemolysin to restore its hemolytic activity

“…8,9 The introduction of such an artificial moiety at the appropriate site allows the acquisition by the target protein of activities and/or structures that are suitable for the desired purpose and that are not necessarily related to its original biological functions. 16 Here, we propose a rather different approach to protein engineering compared with the conventional molecular design. In this context, Lopez-Rodriguez et al have recently reported the replacement of amino acid side chains with synthetic moieties with chemical properties that were similar to those of the original side chain.…”