Manikomycin, a Natural Antibiotic That Hits a Never-Targeted Ribosome Site, Kills Drug-Resistant Bacteria in Nature Study
McMaster-led researchers report in Nature a depsipeptide antibiotic that blocks the bacterial ribosome's E-site, a target no existing drug uses.
Overview
A research team led by McMaster University has identified a natural antibiotic, manikomycin, that kills drug-resistant bacteria by striking a target no antibiotic in clinical use has ever exploited: the exit site of the bacterial ribosome. According to McMaster University, the compound has shown early effectiveness against priority pathogens including Salmonella, E. coli, and Klebsiella, and the work was published in Nature on June 3, 2026.
What We Know
Manikomycin is produced by the soil bacterium Streptomyces rimosus, the same species that gives the long-used antibiotic oxytetracycline, McMaster University reports. The study, titled “A natural depsipeptide antibiotic binds the E-site of the bacterial ribosome,” describes a cyclic depsipeptide that the researchers isolated from the producing strain, designated WAC 7405, through bioactivity-guided purification of bacterial extracts, according to the primary paper on PubMed Central.
The mechanism is what sets manikomycin apart. The ribosome is the molecular machine every cell uses to translate genetic instructions into proteins, and most existing antibiotics that target it bind well-worn sites. Manikomycin instead binds the so-called E-site, or exit site, of the large subunit of the bacterial ribosome, GEN reports. By occupying that pocket, it prevents the 3’ end of the transfer RNA from entering the E-site and stalls the translocation step of protein synthesis, according to the Nature paper. GEN describes it as the first antibacterial agent known to target the E-site in the large ribosomal subunit.
The team resolved how the molecule docks using cryo-electron microscopy at 2.5 angstrom resolution, refined to 2.4 angstroms on the 50S subunit, according to the primary paper. Because the binding pocket is distinct from the targets of other translation-inhibiting drugs, the paper reports that manikomycin is insensitive to the resistance mechanisms that protect bacterial pathogens from existing ribosome-targeting antibiotics.
Gerry Wright, a professor in the Department of Biochemistry and Biomedical Sciences at McMaster and scientific director of the Michael G. DeGroote Institute of Infectious Disease Research, framed the novelty bluntly. “Not a single antibiotic prescribed in clinics today does what manikomycin does. Not azithromycin, not tetracycline — none of them,” he said, as quoted by McMaster University. Because the target has never been under drug pressure before, he argued, bacteria have not evolved defenses against it. “But across the history of medicine, we’ve put absolutely no selective pressure on this particular target, so bacteria have no existing resistance mechanisms for manikomycin,” Wright said, according to McMaster University.
In early testing, the compound was active against multidrug-resistant Enterobacteriaceae and was not toxic to human cells, GEN reports. The primary paper records no hemolytic activity or toxicity against human HEK293T cells at concentrations up to 256 micrograms per milliliter, and reports a bactericidal effect in time-kill assays. The researchers also demonstrated efficacy in a living host, using the nematode C. elegans infected with Klebsiella pneumoniae as an in vivo model, according to the paper.
The discovery is the fourth new antibiotic candidate to emerge from Wright’s lab in just over a year, Medical Xpress reports, and the team has produced 60 derivatives of manikomycin as it works to optimize the molecule. The work was a collaboration between McMaster, the University of Illinois Chicago, and the University of Hamburg in Germany, McMaster University reports.
Wright also pushed back on a common assumption in the field — that soil microbes have already surrendered all their useful antibiotics. “There is an overwhelming perception in science that these bacteria have been mined completely dry,” he said, as quoted by Medical Xpress. First author Manpreet Kaur, a postdoctoral fellow in Wright’s lab, added: “There is likely so much still to be discovered through fractionation,” according to Medical Xpress.
What We Don’t Know
Manikomycin remains a preclinical candidate. The reported efficacy comes from laboratory assays and an invertebrate infection model rather than mammalian or human trials, according to the primary paper, and the team is still optimizing the molecule’s properties across its 60 derivatives, as GEN reports. The published work does not establish a timeline to clinical trials. Wright signaled the work is ongoing: “We’re excited about this molecule’s potential. There’s a clear path forward, and we may even be able to expand its spectrum so that it eventually affects even more bacteria, too,” he said, according to McMaster University.
Analysis
The significance of manikomycin lies less in any single laboratory result than in the target it validates. Antibiotic development has long struggled with cross-resistance: new drugs that hit familiar molecular sites can be neutralized by resistance machinery bacteria already carry. A binding pocket with no history of drug exposure sidesteps that problem, at least initially. The finding lands against a backdrop of a contracting pipeline; as The Machine Herald previously reported, the number of antibiotic candidates from large research-based companies has fallen sharply over five years even as resistant infections rise. A genuinely novel mechanism — if it survives the long road from nematode model to human trials — would be a meaningful addition to a thin arsenal.