Cloning, yeast expression, purification and biological activity of a truncated form of the soybean 7S globulin α′ subunit involved in Hep G2 cell cholesterol homeostasis

Abstract

A truncated form of alpha' chain (talpha'), the soybean 7S globulin subunit previously demonstrated to be active in controlling the cholesterol and triglyceride homeostasis in in vitro and in vivo models, was cloned and expressed in the yeast Pichia pastoris. The recombinant polypeptide spanned 216 amino acid residues from the N-terminal side and included the N-terminal extension region of the soybean subunit. The talpha' polypeptide was purified by conventional biochemical techniques, and its potential to modulate the activity of low-density lipoprotein (LDL) receptor was evaluated in a human hepatoma cell line (Hep G2) by monitoring the uptake and degradation of labeled LDL. The LDL uptake (+192%) and degradation (+143%) by cells tested at the highest talpha' dose (8 microM) were similar to those found in cells incubated with 1 microM simvastatin, a potent inhibitor of cholesterol biosynthesis. The cell response to talpha' was found to be dose dependent. The use of a recombinant polypeptide ruled out the involvement of any other soybean component. These findings open new prospects in the studies aimed at identifying soybean regulatory (poly)peptide(s) and the mechanism involved in this biological response, as a gateway to their utilization for the management of human health.

IAVPGEVA, IAVPTGVA, and LPYP, three peptides from soy glycinin, modulate cholesterol metabolism in HepG2 cells through the activation of the LDLR-SREBP2 pathway

“…Some investigations have shown that its α′ subunit may have a major role in the cholesterol-lowering properties of soybean (Consonni et al, 2010(Consonni et al, , 2011Duranti et al, 2004). Other authors have focused attention on the isolation and characterization of hypocholesterolaemic peptides from soy protein hydrolyzates.…”

Making the case for edible microorganisms as an integral part of a more sustainable and resilient food production system

“…However, many microorganisms can easily be genetically engineered to produce well-characterized feed proteins from non-microbial sourcesor even produce entirely novel, customized proteins with superior digestibility, tailor-made amino acid profiles and reduced allergenic potential. A number of genes encoding seed storage proteins from plants have successfully been inserted into the genomes of yeast for recombinant protein production at laboratory scale (Consonni et al 2010;Lin et al 2004;Medina-Godoy et al 2006). Such recombinant (and potentially customized) feed protein could allow for a higher inclusion threshold than endogenous microbial protein, potentially to a degree where it could completely replace conventional sources of protein feed.…”

The Role of Grain Legumes in the Prevention of Hypercholesterolemia and Hypertension

“…Recently, two studies demonstrated the ability of a truncated form of the vicilin α subunit (tα ) (Consonni et al, 2010) and a recombinant polypeptide α E polypeptide (α E) (Consonni et al, 2011), in modulating cholesterol homeostasis and the activity of the LDL receptor in HepG2 cells. By monitoring the uptake and degradation of 125 I-LDL, it was demonstrated that the treatments with tα or α E produced significant increases in LDL uptake and degradation, similar to those found in cells incubated with simvastatin (a potent inhibitor of cholesterol biosynthesis).…”