The battle between antibiotics and bacteria has escalated with the rise of superbugs resistant to our strongest medications, posing a major concern. Interestingly, E. coli and many other bacteria, when under attack by antibiotics, adopt a fascinating survival strategy: they slow down their division, stretching into longer, filament-like shapes. This tactic isn’t just a desperate measure but a clever way to dodge the body’s immune system and protect themselves with a shield-like layer. Amidst this microbial arms race, an unexpected discovery has been made. The introduction of annexin A4, a protein from mammals that binds to certain fats in a calcium-dependent manner, into E. coli, amazingly restores the bacteria’s normal division process, even when under the stress of antibiotics. This unexpected helper from the animal world lights a spark of hope, suggesting a new way to disarm resistant bacteria, making them vulnerable once again to antibiotics and our body’s defenses.
Figure 1. Production of bovine annexin A4 in E. coli bacteria restores cell division blocked by antibiotics. Left panel: Bacteria incubated in the antibiotics ampicillin and cephalexin fail to divide as they grow, resulting in an elongated shape that is difficult for white blood cells to consume and destroy. Right panel: When the bacteria also produce bovine annexin A4 the cells can divide again, resulting in bacteria that are smaller and can be “swallowed” by white blood cells and destroyed. (Photographed with dark field light microscopy. Length of the white scale bar in each panel equals 50 micrometers).
In groundbreaking research by Professor Carl Creutz from the University of Virginia, a new method to fight antibiotic resistance has been revealed. Published in Biochemistry and Biophysics Reports, the investigation demonstrates that adding bovine annexin A4 to E. coli can counteract the negative effects of beta-lactam antibiotics, marking a major breakthrough in the battle against resistant bacterial strains.
Professor Creutz shares insights from the beginning of the research, “Introducing a mammalian protein that binds to fats in a calcium-dependent manner, namely bovine annexin A4, into E. coli, was found to counteract the stopping effects on cell division caused by the antibiotics ampicillin, piperacillin, and cephalexin.” This finding hints at a potential new strategy to make bacteria more susceptible to both antibiotic treatments and the body’s immune system by enabling the normal division of bacteria that antibiotics had stopped.
Exploring the methods used in the research, Professor Creutz turned to dark field light microscopy to track the development of bacterial filaments when exposed to antibiotics. This technique, as Professor Creutz explains, “improves the visibility of bacteria against a dark background, making it easier to see changes in the bacterial cell’s shape without the complexities often faced with traditional viewing methods.” This allowed the researchers to see in real-time the effects of annexin A4 on bacterial cells, clearly showing its role in reversing the division-stopping effect caused by antibiotics. Additionally, Professor Creutz used transmission electron microscopy for a closer look at the cell’s structure, confirming what they saw with light microscopy at a more intricate level. These methods together provided a full picture of the effects of annexin A4, connecting the visible changes in bacteria with the deeper molecular actions taking place.
Additionally, Professor Creutz used transmission electron microscopy for a closer look at the cell’s structure, confirming what they saw with light microscopy at a more intricate level. These methods together provided a full picture of the effects of annexin A4, connecting the visible changes in bacteria with the deeper molecular actions taking place.
Figure 2: Electron microscopy of E. coli incubated with the antibiotics indicates detailed effects of calcium on the ability of the annexin to promote cell division. Upper left panel: Bacterial cells without any annexin A4. A mixture of elongated and normal cells is seen. Upper right panel: Bacterial cells producing “normal” annexin A4 with 4 calcium binding sites. Fewer elongated cells are seen because the annexin has caused some cells to divide. Bottom left panel: Bacterial cells producing annexin A4 with only one, very effective calcium binding site. Most of the cells are shorter due to cell division. Bottom right panel: Bacterial cells producing annexin A4 that has had all calcium binding sites removed by mutation. More cells are elongated and “fatter” because removal of all the calcium binding sites has reduced the ability of the annexin to promote cell division. (Length of the black scale bar equals 2.5 micrometers).
“Keeping an eye on the restoration of cell division was key to understanding how annexin A4 affects bacterial cell division under the stress of antibiotics,” Professor Creutz notes, emphasizing the significance of these observations in their discovery. “Our findings point to the importance of calcium binding to the annexin and its attachment to membranes in bringing back cell division,” Professor Creutz further details, shedding light on the molecular groundwork of their results.
The implications of this investigation are significant, suggesting a new path for creating additional treatments to boost the effectiveness of current antibiotics. The University of Virginia has started the process for a patent for the use of annexins in antimicrobial treatments, indicating the potential for practical applications of this discovery.
As the challenge of antibiotic resistance continues to be a global health issue, Professor Creutz’s research offers a beam of hope for more effective treatments. Future efforts will aim to confirm these results in living organisms, potentially leading to innovative treatment strategies against resistant bacterial infections.
JOURNAL REFERENCE
Carl Creutz, “Expression of bovine annexin A4 in E. coli rescues cytokinesis blocked by beta-lactam antibiotics”, Biochemistry and Biophysics Reports, 2023. DOI: https://doi.org/10.1016/j.bbrep.2023.101553.
ABOUT THE AUTHOR
After receiving a B.S. in Physics at Stanford University (1969), a M.S. in Physics from the University of Wisconsin (1970), and a Ph.D. in Biophysics from Johns Hopkins University (1976), Dr. Creutz conducted basic research in molecular and cell biology at the NIH in Bethesda, MD, as a Staff Fellow (1976-1979) and Senior Staff Fellow (1980-1981). In 1981, he was recruited to the Department of Pharmacology at the University of Virginia as an Assistant Professor. In 1987, he was promoted to Associate Professor, and in 1994 to Full Professor. In 2003, Dr. Creutz was elected as the Harrison Professor of Medical Teaching in Pharmacology, a position he holds concurrently with his position as Professor of Pharmacology.
