The Structure of the Superantigen Exfoliative Toxin A Suggests a Novel Regulation as a Serine Protease
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- 作者：Gregory M. Vath ; Cathleen A. Earhart ; James V. Rago ; Michael H. Kim ; Gregory A. Bohach ; Patrick M. Schlievert ; and Douglas H. Ohlendorf
- 刊名：Biochemistry
- 出版年：1997
- 出版时间：February 18, 1997
- 年：1997
- 卷：36
- 期：7
- 页码：1559 - 1566
- 全文大小：314K
- 年卷期：v.36,no.7(February 18, 1997)
- ISSN：1520-4995
文摘
Exfoliative toxin A (ETA) causes staphylococcal scalded skinsyndrome which is characterizedby a specific intraepidermal separation of layers of the skin. Themechanism by which ETA causes skinseparation is unknown although protease or superantigen activity hasbeen implicated. The X-ray crystalstructure of ETA has been solved in two crystal forms to 2.1 and 2.3 Åresolution and R-factors of 17%and 19%, respectively. The structures indicate that ETA belongsto the chymotrypsin-like family of serineproteases and cleaves substrates after acidic residues. Theconformation of a loop adjacent to the catalyticsite is suggested to be key in regulating the proteolytic activity ofETA through controlling whether themain chain carbonyl group of Pro192 occupies the oxyanion hole. Aunique amino-terminal domaincontaining a 15-residue amphipathic 
helix may also be involved inprotease activation through bindinga specific receptor. Substitution of the active site serineresidue with cysteine abolishes the ability ofETA to produce the characteristic separation of epidermal layers butnot its ability to induce T cellproliferation.
helix may also be involved inprotease activation through bindinga specific receptor. Substitution of the active site serineresidue with cysteine abolishes the ability ofETA to produce the characteristic separation of epidermal layers butnot its ability to induce T cellproliferation.