alpha-Hemolysin, gamma-hemolysin, and leukocidin from Staphylococcus aureus: distant in sequence but similar in structure. |
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Authors: | E Gouaux M Hobaugh and L Song |
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Institution: | Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032, USA. |
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Abstract: | alpha-Hemolysin from Staphylococcus aureus assembles from a water-soluble, monomeric species to a membrane-bound heptamer on the surface of target cells, creating water-filled channels that lead to cell death and lysis. Staphylococcus aureus also produces the gamma-hemolysin and leukocidin toxins, which function as two component toxins in the disruption and lysis of erythrocytes and leukocytes. Analysis of the aligned sequences of alpha-hemolysin, gamma-hemolysin, and leukocidin in the context of the alpha-hemolysin heptamer structure supports the conclusion that even though the level of sequence identity between alpha-hemolysin and the gamma-hemolysin and leukocidin toxins is in the so-called twilight zone, the three-dimensional structures of the protomers are probably conserved. By analogy with alpha-hemolysin, gamma-hemolysin and leukocidin may also form oligomeric, transmembrane channels in which an antiparallel beta-barrel constitutes the primary membrane-embedded domain. |
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Keywords: | α-hemolysin γ-hemolysin heptameric channels leukocidin pore-forming bacterial toxins Staphylococcus aureus trans-membrane β-barrel |
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