Protamine-like proteins have bactericidal activity. The first evidence in Mytilus galloprovincialis

Abstract

The major acid-soluble protein components of the mussel Mytilus galloprovincialis sperm chromatin consist of the protamine-like proteins PL-II, PL-III and PL-IV, an intermediate group of sperm nuclear basic proteins between histones and protamines. The aim of this study was to investigate the bactericidal activity of these proteins since, to date, there are reports on bactericidal activity of protamines and histones, but not on protamine-like proteins. We tested the bactericidal activity of these proteins against Gram-positive bacteria: Enterococcus faecalis and two different strains of Staphylococcus aureus, as well as Gram-negative bacteria: Proteus mirabilis, Proteus vulgaris, Pseudomonas aeruginosa, Salmonella typhmurium, Enterobacter aerogenes, Enterobacter cloacae, and Escherichia coli. Clinical isolates of the same bacterial species were also used to compare their sensitivity to these proteins. The results show that Mytilus galloprovincialis protamine-like proteins exhibited bactericidal activity against all bacterial strains tested with different minimum bactericidal concentration values, ranging from 15.7 to 250 µg/mL. Furthermore, these proteins were active against some bacterial strains tested that are resistant to conventional antibiotics. These proteins showed very low toxicity as judged by red blood cell lysis and viability MTT assays and seem to act both at the membrane level and within the bacterial cell. We also tested the bactericidal activity of the product obtained from an in vitro model of gastrointestinal digestion of protamine-like proteins on a Gram-positive and a Gram-negative strain, and obtained the same results with respect to undigested protamine-like proteins on the Gram-positive bacterium. These results provide the first evidence of bactericidal activity of protamine-like-proteins.

Molecular effects of copper on the reproductive system of mytilus galloprovincialis

“…We have already reported new insights into PL component organization in the sperm chromatin of M. galloprovincialis (Vassalli et al, ). Further, we have recently proposed the PL proteins both as antibacterial agents (Notariale et al, ) and as emerging biomarkers for cadmium impact assessment on M. galloprovincialis (Piscopo, Notariale et al, , Piscopo, Trifuoggi, Notariale et al, ). In the present work, we evaluated the molecular effects on the reproductive system of M. galloprovincialis after mussels' exposure for 24 hr to 15 µM CuCl 2 .…”

Cecropin-like antimicrobial peptide protects mice from lethal E.coli infection

“…However, in virtually any organism in which they have been sought, novel AMPs have been found. Recently AMPs have also been identified in a broader range of organisms such as plants, Feijoa sellowiana Berg fruit [48] and shellfish Mytilus galloprovincialis mussel [49]. This argues that there is an inexhaustible supply of natural AMPs and we have barely begun to identify, catalog and test them experimentally and clinically.…”

Molluscan Compounds Provide Drug Leads for the Treatment and Prevention of Respiratory Disease

“…The recent work of Miller et al [176] using 7,8-dideoxygriseorhodin C (DC) is notable: MIC values for DC (0.08-0.12 µg/mL) were lower than the control antibiotic oxacillin (1.59-6.24 µg/mL), and both the number of colony-forming units and MICs for DC and oxacillin were reduced >100 fold (i.e., synergistic effects) when present in combination (Table 5, Figure 2). Extracts from the sperm of the Mediterranean mussel (Mytilus galloprovincialis) have displayed bactericidal activity against clinical S. aureus strains, as well as negligible toxicity and resistance to acid digestion (i.e., suitable for oral administration) [187]. Wei et al [188] prepared two recombinant proteins (rSgSABL-1 and -2) from lectins of the razor clam Solen grandis, which exhibited strong binding affinity to S. aureus peptidoglycan, increased phagocytic and encapsulation activity in vitro, and generated reactive antibodies in vivo (Tables 5 and 7).…”