Novel tetrapeptide inhibitors of bacterial protein synthesis produced by a Streptomyces sp.
In the course of a microbial product screening aimed at the discovery of novel antibiotics acting on bacterial protein synthesis, a complex of three structurally related tetrapeptides, namely, GE81112 factors A, B, and B1, was isolated from a Streptomyces sp. The screening was based on a cell-free assay of bacterial protein synthesis driven by a model mRNA containing natural initiation signals. In this study we report the production, isolation, and structure determination of these novel, potent and selective inhibitors of cell-free bacterial protein synthesis, which stably bind the 30S ribosomal subunit and inhibit the formation of fMet-puromycin. They did not inhibit translation by yeast ribosomes in vitro. Spectroscopic analyses revealed that they are tetrapeptides constituted by uncommon amino acids. While GE81112 factors A, B, and B1 were effective in inhibiting bacterial protein synthesis in vitro, they were less active against Gram-positive and Gram-negative bacterial cells. Cells grown in minimal medium were more susceptible to the compounds than those grown in rich medium, and this is most likely due to competition or regulation by medium components during peptide uptake. The novelty of the chemical structure and of the specific mode of action on the initiation phase of bacterial protein synthesis makes GE81112 a unique scaffold for designing new drugs.
University of Camerino, Via Camerini 2, 62032 Camerino, Italy.
Letizia
L
Brandi
Ameriga
A
Lazzarini
Linda
L
Cavaletti
Monica
M
Abbondi
Emiliana
E
Corti
Ismaela
I
Ciciliato
Luciano
L
Gastaldo
Alessandra
A
Marazzi
Marina
M
Feroggio
Attilio
A
Fabbretti
Alessandro
A
Maio
Luigi
L
Colombo
Stefano
S
Donadio
Flavia
F
Marinelli
Daniele
D
Losi
Claudio O
CO
Gualerzi
Enrico
E
Selva
D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology; D000890:Anti-Infective Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004353:Drug Evaluation, Preclinical / Q000379:methods; D004926:Escherichia coli / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D010442:Peptide Chain Initiation, Translational / Q000187:drug effects; D010455:Peptides / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D014176:Protein Biosynthesis; D011500:Protein Synthesis Inhibitors / Q000378:metabolism / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism; D013302:Streptomyces / Q000378:metabolism*; D013997:Time Factors
D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D001426:Bacterial Proteins; D010455:Peptides; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger