%0 Journal Article %A Miyamoto, Masahiko %A Onozato, Naohiko %A Selvakumar, Dakshnamurthy %A Kimura, Tetsuya %A Furuichi, Yasuhiro %A Komiyama, Tadazumi %T The role of the histidine-35 residue in the cytocidal action of HM-1 killer toxin %D 2006 %J Microbiology, %V 152 %N 10 %P 2951-2958 %@ 1465-2080 %R https://doi.org/10.1099/mic.0.29100-0 %K HM-1, HM-1 killer toxin %K DEPC, diethylpyrocarbonate %K CD, circular dichroism %I Microbiology Society, %X Diethylpyrocarbonate modification and site-directed mutagenesis studies of histidine-35 in HM-1 killer toxin (HM-1) have shown that a specific feature, the imidazole side chain of histidine-35, is essential for the expression of the killing activity. In subcellular localization experiments, wild-type HM-1 was in the membrane fraction of Saccharomyces cerevisiae BJ1824, but not the HM-1 analogue in which histidine-35 was replaced by alanine (H35A HM-1). Neither wild-type nor H35A HM-1 was detected in cellular fractions of HM-1-resistant yeast S. cerevisiae BJ1824 rhk1Δ : : URA3 and HM-1-insensitive yeast Candida albicans even after 1 h incubation. H35A HM-1 inhibited the activity of partially purified 1,3-β-glucan synthase from S. cerevisiae A451, and its extent was almost the same as wild-type HM-1. Co-immunoprecipitation experiments showed that wild-type and H35A HM-1 directly interact with the 1,3-β-glucan synthase complex. These results strongly suggest that histidine-35 has an important role in the cytocidal action of HM-1 that participates in the binding process to the HM-1 receptor protein on the cell membrane, but it is not essential for the interaction with, and inhibition of, 1,3-β-glucan synthase. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.29100-0