Mechanism of the cytotoxic effect exerted by type C botulinum hemagglutinin

2014 Fiscal Year Final Research Report

• Project/Area Number: 25860319
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Bacteriology (including mycology)
• Research Institution: Osaka University
• Principal Investigator: SUGAWARA Yo 大阪大学, 微生物病研究所, 特任助教(常勤) (70452464)
• Project Period (FY): 2013-04-01 – 2015-03-31
• Keywords: ボツリヌス毒素 / ヘマグルチニン / シアル酸 / ガングリオシド / GM3 / 糖鎖アレイ / アクチン骨格

Outline of Final Research Achievements

Botulinum neurotoxin is conventionally divided into seven serotypes designated A-G, and is produced as large protein complexes through associations with nontoxic components, such as hemagglutinin (HA). Type C HA (HA/C) is known to affect cell morphology and viability, the mechanism of which remains unknown. In this study, I identified GM3 as the target molecule of HA/C. I found that sialic acid binding of HA is essential for the activity. It was abolished when cells were pretreated with an inhibitor of ganglioside synthesis. Consistent with this, HA/C bound to GM3 and a-series gangliosides in a glycan array. In parallel, I isolated clones resistant to HA/C activity from a susceptible mouse fibroblast strain. These cells lacked the expression of ST-I, the enzyme that transfers sialic acid to lactosylceramide to yield GM3. In addition, these clones became sensitive to HA/C activity when GM3 was expressed by transfecting the ST-I gene. Thus, HA/C affects cells in a GM3-dependent manner.

Free Research Field

細菌学、細胞生物学