In some respects, animals and amoeba aren’t that different. For example, both are at risk of potentially deadly assaults by bacteria and have developed methods to prevent them. Researchers at Baylor College of Medicine report within the journal Science Advances that Dictyostelium discoideum, the soil-dwelling single-celled amoeba that feeds on bacteria, builds a barrier around its colonies that counteracts bacterial makes an attempt to penetrate them, facilitates amoebal feeding and protects them from oxidative stress.
“We were shocked to find that, when exposed to some kinds of Gram-negative bacteria similar to Klebsiella pneumoniae, however not Gram-positive bacteria, D. discoideum secretes into its surroundings massive amounts of CadA, a protein until now known only as a cell adhesion molecule that contributes to the amoeba’s improvement,” mentioned corresponding author Dr. Adam Kuspa, professor of biochemistry and molecular biology and senior vice president and dean of analysis at Baylor. “We analyzed CadA and decided that it’s a lectin, a molecule that binds to carbohydrates, and mixing CadA with K. pneumoniae resulted in clumps of bacteria.”
Kuspa and his colleagues then investigated the impact of the lack of CadA on the amoeba’s ability to form colonies or plaques on a film of bacteria, typical laboratory conditions to study amoebae. They deleted the CadA gene and found that only 20 % of the amoebae survived and formed plaques when set to develop on a film of K. pneumoniae. However, the identical CadA-deficient amoebae grew the same as amoebae with CadA when set to develop on Gram-positive bacteria.