Feglymycin

Feglymycin, a peptide antibiotic produced by Streptomyces sp. DSM 11171, consists mostly of nonproteinogenic phenylglycine-type amino acids. It possesses antibacterial activity against methicillin-resistant Staphylococcus aureus strains and antiviral activity against HIV. Inhibition of the early steps of bacterial peptidoglycan synthesis indicated a mode of action different from those of other peptide antibiotics. Here we describe the identification and assignment of the feglymycin (feg) biosynthesis gene cluster, which codes for a 13-module nonribosomal peptide synthetase (NRPS) system. Inactivation of an NRPS gene and supplementation of a hydroxymandelate oxidase mutant with the amino acid l-Hpg proved the identity of the feg cluster. Feeding of Hpg-related unnatural amino acids was not successful. This characterization of the feg cluster is an important step to understanding the biosynthesis of this potent antibacterial peptide.

Objectives:Lignosulfonic acid (LA), a low-cost lignin-derived polyanionic macromolecule, was extensively studied for its anti-HIV and anti-HSV activity in various cellular assays, its mechanism of viral inhibition and safety profile as potential microbicide.Results:LA demonstrated potent inhibitory activity of HIV replication against a wide range of R5 and X4 HIV strains and prevented the uptake of HIV by bystander CD4+ T cells from persistently infected T cells in vitro (IC50: 0.07 - 0.34 μM). LA also inhibited HSV-2 replication in vitro in different cell types (IC50: 0.42 - 1.1 μM) and in rodents in vivo. Furthermore, LA neutralized the HIV-1 and HSV-2 DC-SIGN-mediated viral transfer to CD4+ T cells (IC50: ~1 μM). In addition, dual HIV-1/HSV-2 infection in T cells was potently blocked by LA (IC50: 0.71 μM). No antiviral activity was observed against the non-enveloped viruses Coxsackie type B4 and Reovirus type 1. LA is defined as a HIV entry inhibitor since it interfered with gp120 binding to the cell surface of T cells. Pretreatment of PBMCs with LA neither increased expression levels of cellular activation markers (CD69, CD25 and HLA-DR), nor enhanced HIV-1 replication. Furthermore, we found that LA had non-antagonistic effects with acyclovir, PRO2000 or LabyA1 (combination index (CI): 0.46 - 1.03) in its anti-HSV-2 activity and synergized with tenofovir (CI: 0.59) in its anti-HIV-1 activity. To identify mechanisms of LA resistance, we generated in vitro a mutant HIV-1 NL4.3LAresistant virus, which acquired seven mutations in the HIV-1 envelope glycoproteins: S160N, V170N, Q280H and R389T in gp120 and K77Q, N113D and H132Y in gp41. Additionally, HIV-1 NL4.3LAresistant virus showed cross-resistance with feglymycin, enfuvirtide, PRO2000 and mAb b12, four well-described HIV binding/fusion inhibitors. Importantly, LA did not affect the growth of vaginal Lactobacilli strains.Conclusion:Overall, these data highlight LA as a potential and unique low-cost microbicide displaying broad anti-HIV and anti-HSV activity.

The novel peptide feglymycin has been isolated from cultures of Streptomyces sp. DSM 11171 by solid phase extraction, size exclusion chromatography and repeated reversed-phase chromatography. The molecular weight was found to be 1900.90 g/mol and the molecular formula is C95H97Nl3O30. Feglymycin contains 13 amino acids of which four are 3-hydroxyphenylglycine and five are 3,5-dihydroxyphenylglycine residues. The structure of the linear peptide has been determined by 1H and 13C NMR spectroscopy. The sequence was confirmed by the observed mass spectroscopic fragmentation pattern. As well as having weak antibacterial activity, feglymycin inhibits the replication of the human immunodeficiency virus (HIV) in vitro.