Amylosin from Bacillus amyloliquefaciens, a K+ and Na+ channel-forming toxic peptide containing a polyene structure

The Peptide Toxin Amylosin of Bacillus amyloliquefaciens from Moisture-Damaged Buildings Is Immunotoxic, Induces Potassium Efflux from Mammalian Cells, and Has Antimicrobial Activity

“…Results are expressed as means Ϯ minimum and maximum values and are representative of two independent experiments. sure to a concentration down to 300 ng amylosin ml Ϫ1 was shown here to be sufficient to generate a major potassium efflux from live cells, similar to that shown previously for isolated mitochondria (2). Therefore, exposure to extremely low concentrations of amylosin may initiate in vivo potassium leakage from human cells (intracellular concentration of potassium of 150 mM [32]) down the concentration gradient toward that of blood plasma (potassium concentration, 3.5 to 5.0 mM [32]).…”

“…Absorbance at a wavelength 365 nm was used for detection. Quantification of amylosin was done by a HPLC-UV method using amphotericin B (Sigma-Aldrich, St. Louis, MO, USA) as a reference compound, as described by Mikkola et al (2). HPLC-mass spectrometry (HPLC-MS) analysis of amylosin was done as described previously (6) using the HPLC conditions presented above.…”

“…Our results also showed that amylosin-producing B. amyloliquefaciens 19b can inhibit the growth of several bacteria with very different cell wall compositions as well as growth of indoor fungi. In addition to amylosin, B. amyloliquefaciens 19b produces surfactin and antifungal fengycin (2,43). Strains of B. amyloliquefaciens producing several antibacterial and antifungal linear and cyclic lipopeptides (e.g., fengycins, iturins, and surfactins) have also been isolated from, e.g., marine environments, mangrove forests, and plant rhizospheres (30,44,45).…”

“…A mylosin is a heat-stable 1,197-Da peptide toxin originally found to be produced by strains of Bacillus amyloliquefaciens isolated from moisture-damaged buildings (1,2). B. amyloliquefaciens belongs to the Bacillus subtilis group, members of which have been found in high numbers in moisture-damaged buildings where occupants have experienced building-related ill health symptoms (3,4).…”

“…B. amyloliquefaciens belongs to the Bacillus subtilis group, members of which have been found in high numbers in moisture-damaged buildings where occupants have experienced building-related ill health symptoms (3,4). Amylosin forms cation-permeant ion channels with high selectivity for K ϩ in lipid membranes (5) and thus depolarizes the plasma membrane and the mitochondria inside live mammalian cells, disrupting cellular ion homeostasis, mitochondrial functions, and energy metabolism (1,2). It has been suggested that amylosin causes health risks for people living or working in moisture-damaged buildings contaminated with amylosin-producing bacteria (1).…”