Preliminary studies on the zinc-induced metallothionein protein with antibacterial activity in housefly larvae,Musca Domestica

Abstract

Three isoforms of metallothionein protein induced with Zinc were isolated and purified from housefly larvae, Musca domestica, by gel filtration on Sephadex G-75, G-25 and anion exchange on DEAE-52 chromatography. Among them, one was found to possess antibacterial activity, and was further characterized by SDS-polyacrylamide gel electrophoresis, sulphydryl group determination, enzyme hydrolysis, and spectra property. Our results showed that the novel protein has the characteristics of heat-stable, low-molecular weight (6 kDa), rich-cysteine (approximately 12 cysteine residues in one molecule), metal affinity, and antibacterial activity. This paper was the first to report that metallothionein had antibacterial activity. We expect that this characteristic would give some help to investigate definite physiological functions of metallothionein.

Evidence for a Potential Role of Metallothioneins in Inflammatory Bowel Diseases

“…Since Crohn's disease is characterized by defective T cell apoptosis, whereas T cells from ulcerative colitis patients show a strong activation induced apoptosis, the role of MTs might be different in these two diseases. MTs have also been accredited antimicrobial properties [73, 74], which might be another relevant feature given the defective interaction of the host with the mucosal flora in IBD. Macrophages isolated from MTnull mice showed a significantly lower bactericidal effect on Staphylococcus aureus than macrophages from control mice.…”

“…Furthermore, LPS- and TNF- α -stimulated MT-null macrophages produced less NO than those from control mice, which was due to reduced activity of inducible NO synthase [73]. One MT isoform that was isolated and purified from housefly larvae had direct antibacterial effects on Escherichia coli as assayed by the plate growth inhibition assay [74]. …”

“…This correlates with the reported antibacterial activity that was associated with MT function. This activity might be mediated directly by MTs themselves [74] or indirectly through nitric oxide production [73]. Endogenous MT protected against acute lung injury induced by LPS, especially against pulmonary oedema [56].…”

Antiviral, Immunomodulatory, and Free Radical Scavenging Activities of a Protein-Enriched Fraction from the Larvae of the Housefly,Musca domestica

“…Various biological and medicinal activities of extracts from M. domestica larvae have been reported, e.g., antibacterial, antiviral, anti-allergic, antiinflammatory, antitumor, and radical scavenging activity (Meylaers et al 2004; Jin et al 2005; Liu et al 2011; Ratcliffea et al 2011). Our previous experiments also suggested that the homogenate of the larvae of this fly possessed antiviral activity against HbsAg and influenza viruses and hydroxyl radical scavenging activity in vi tro (Wang et al 2006).…”

Novel Families of Toxin-like Peptides in Insects and Mammals: A Computational Approach

“…There is no evidence of metallothioneinlike toxins, and the high number of cysteine residues is used in the coordination of heavy metals rather than in the forming of disulfide bonds. However, antibacterial activity of a metallothionein protein expressed in housefly larvae has been reported recently, 17 possibly suggesting that the classification of metallothioneins as incorrect predictions may need to be reconsidered. The groups ICI, Toxin, Neurotoxin and Antibacterial are based on UniProt keywords.…”