2001 Fiscal Year Final Research Report Summary
Crystallographical and molecular biological analysis of ia component of C. perfringens iota-toxin
| Project/Area Number |
12670270
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Bacteriology (including Mycology)
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| Research Institution | Tokushima Bunri University |
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Principal Investigator |
SAKURAI J Tokushima Bunri Univ., Fac. Pharm. Sci. full Professor, 薬学部, 教授 (80029800)
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| Co-Investigator(Kenkyū-buntansha) |
KOBAYASHI Keiko Tokushima Bunri Univ., Fac. Pharm. Res. Associate, 薬学部, 助手 (90170315)
OCHI Sadayuki Tokushima Bunri Univ., Fac. Pharm. Res. Associate, 薬学部, 助手 (80268705)
NAGAHAMA Masahiro Tokushima Bunri Univ., Fac. Pharm. Sci. Asso. Professor, 薬学部, 助教授 (40164462)
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| Project Period (FY) |
2000 – 2001
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| Keywords | Clostridium perfringens / iotaa component / ADP-Ribosylation / NAD / crystallogaraphy / site-directed mutagenesis / ADP-ribosylatiing toxin / Sn1 type reaction |
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| Research Abstract |
The iotaa component (ia) of Clostridium perfringens ADP-ribosylates nonmuscld (β/γ actin and skeletal muscle α-actin. Here, we showed crystal structures of Ia complex with NADH at 1.8Å. It was found that Ia can be divided into two domains, termed the N-domain and the C-domain that has a cavity which binds NADH. A site-directed mutagenesis based on the structure suggested that the catalytic mechanism of Ia proceeds via Snl type reaction as follows ; the positively charged atoms from Arg295 and Arg352 electrically interact with α- and β-phosphate groups of NAD^+, respectively, Glu380 fixes the ribose position, the benzene ring of Phe349 restricts the nicotinamide ring rotation and the nicotinamide carboxyamide forms hydrogen bonds with the main chain amide and carbonyl of Arg296.The specific binding of NAD^+ to Ia induces a conformational change in NAD^+ that results in a ring-like conformation of NAD in the complex. The α-phosphate group could be most important for cleavage via Snl-type reaction, by making a hydrogen bond with the amino group of nicotinamide (distance of 2.92Å) and then withdrawing the electron from the amino group. Thus the hydrogen bond formation induces the spontaneous cleavage of N-glycoside bond. The resulting oxocarbonium cation of the ADP-ribosyl moiety should be stabilized by chelation with the negatively charged carboxylate group of Glu378.The Arg177 of actin is located near the oxocarbonium cation upon Ia-actin complex formation. Then the ADP-ribose group is transferred to the Arg177 of actin.
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Research Products
(4 results)
