Characterization of domain borders and of a naturally occurring major fragment of staphylococcal α‐toxin

FEBS Letters

Thelestam, Monica¹  Blomqvist, Lennart¹  Bergman, Tomas¹  Jörnvall, Hans¹ 

[1] Departments of Bacteriology, Karolinska Institute, S-104 01 Stockholm, Sweden

关键词: Staphyloccocal α-toxin;    Native fragment;    Membrane binding;    Tryptic cleavage;    Electroblotting;    Amino acid sequence analysis;   

DOI  :  10.1016/0014-5793(87)81422-9

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

A naturally occurring staphylococcal α-toxin fragment with an apparent membrane-binding capacity but without toxic activities is shown to be derived from the C-terminal half of the intact polypeptide chain by cleavage between position 134 and 135 in the parent molecule. The resulting N-terminus is slightly ragged with a fragment start not only at position 135 but also at the adjacent position 136. Another naturally occurring fragment starts at position 9, derived from an original cleavage between position 8 and 9 in the parent molecule. Analysis of non-purified fragment mixtures confirmed these positions and established that only one further region, at positions 71–72, is partly sensitive to proteolysis under natural conditions. Trypsin treatment has limited effects on the native toxin molecule, giving essentially only two initial cleavages with resultant large fragments. One of these cleavages is at the peptide bond between position 131 and 132, thus only three residues away from the position of the major naturally occurring cleavage. The other bond sensitive to trypsin is between position 8 and 9, thus identically positioned to the cleavage occurring naturally. Together, all the cleavages define a region in a central segment of the polypeptide chain that has all the properties of an inter-domain segment. The C-terminal half appears to constitute a membrane-binding domain, and the N-terminal half a structure needed for full biological activity, functionally subdividing the parent polypeptide chain.

【 授权许可】

Unknown