Effects of eliminating a disulfide bridge within domain II of Pseudomonas aeruginosa exotoxin A.
AUTOR(ES)
Madshus, I H
RESUMO
Cysteines 265 and 287 of Pseudomonas aeruginosa exotoxin A (ETA) were substituted by serine, thereby eliminating a disulfide bridge within domain II, the putative membrane insertion-translocation domain. Purified mutant toxin was 80-fold less toxic for mouse L cells than was wild-type ETA while retaining the same specific activity in the ADP-ribosyltransferase reaction as did wild-type toxin. Binding of the nonionic detergent Triton X-114 by mutant ETA occurred at a slightly higher pH than did binding by wild-type ETA, suggesting that the mutant protein more readily undergoes a conformational change exposing hydrophobic regions. Data are presented supporting the notion that the mutant and wild-type toxins enter from the same intracellular compartment. The lower cytotoxicity of the mutant protein could be due to accelerated intracellular degradation or abortive, premature membrane insertion.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=313813Documentos Relacionados
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