P. aeruginosa protein plugs block antibiotic entry, researchers report

Pseudomonas aeruginosa uses two proteins to block antibiotic entry through a channel in its outer membrane, Sungkyunkwan University reported on October 7 in an announcement published by Phys.org. The finding identifies a possible target for research against a bacterium associated with difficult-to-treat healthcare infections, but does not establish a treatment for patients.

The announcement highlights research published in Nature Communications on May 29, 2026; it does not announce newly published October experiments. The university identifies the research leaders as Hongbaek Cho of Sungkyunkwan University and Jeong Min Chung of the Catholic University of Korea. Oh Hyun Kwon is the paper’s first-listed author.

How SlkA and SlkB seal an antibiotic entry route

The bacterium’s outer membrane acts as a barrier that restricts antibiotic penetration. Yet the organism also needs structures that cross that barrier. Threadlike appendages called type IV pili help it attach to host cells, creating a problem: the machinery used to build them includes a channel through the protective membrane.

According to the university report, two proteins called SlkA and SlkB act as physical plugs inside that channel. They protect a vulnerable stage before pilus assembly is complete, limiting the entry of antibiotics while the bacterium prepares the machinery needed to produce its surface appendages.

The team used cryo-electron microscopy to examine the channel’s structure. The paper reports material occupying the channel in preparations expressing the plug proteins, with protein analysis supporting its identification as SlkA or SlkB. This supplied structural evidence alongside the experiments testing antibiotic sensitivity.

Why the bacterial strain matters

Researchers used genetic screening with erythromycin to identify genes contributing to the membrane barrier. In the strain initially tested, deleting both plug genes increased sensitivity to several antibiotics. Expressing either gene restored erythromycin resistance, supporting a protective role for the proteins under those experimental conditions.

Removing PilQ also suppressed the plug-deficient strain’s erythromycin sensitivity. That result supported the channel’s role as an entry route: the heightened sensitivity depended on the presence of the channel that the missing proteins would otherwise help seal.

A crucial qualification emerged when the researchers compared strains. The initial strain had defective pilus-associated movement. In movement-proficient strains, deleting the plug genes did not produce obvious erythromycin sensitivity under the plate-assay conditions reported in the paper. Disabling the plugs therefore did not have the same visible effect in every strain tested.

Repairing the initial strain’s pilC defect restored erythromycin resistance even with the plug genes deleted. More sensitive assays nevertheless detected a smaller plug-dependent effect. Together, these results support overlapping protection from the plugs and assembly machinery, while limiting any claim that removing the plugs alone reliably overcomes resistance.

Who is affected by Pseudomonas aeruginosa infections

The US Centers for Disease Control and Prevention says P. aeruginosa infections typically occur in healthcare settings. They can affect the bloodstream, lungs, urinary tract and sites following surgery. Patients on ventilators, people with catheters and those with open surgical or burn wounds are especially vulnerable.

Some strains resist nearly all antibiotics, including carbapenems, according to CDC. That does not mean every P. aeruginosa strain is multidrug resistant. As historical context, the agency estimates that multidrug-resistant P. aeruginosa caused 32,600 infections among hospitalized patients and 2,700 deaths in the United States in 2017. Those are not current-year estimates.

What the findings establish about future treatments

The university presents the mechanism as a possible foundation for future antimicrobial agents or therapies that help antibiotics work. The proposed opportunity is to disrupt protection against antibiotic entry. The reported strain differences are an important limit on translating that idea into a broadly effective intervention.

Neither the university announcement nor the reported laboratory findings establish patient benefit, clinical efficacy, an approved plug-targeting drug or a treatment timetable. The Nature Communications study establishes a mechanism and experimental qualifications; CDC’s separate account explains the infection burden, without offering a study-specific endorsement.