Identification of serine138 residue in the 4-residue segment K135K1361137S138 of LukS-I component of Staphylococcus intermedius leukocidin crucial for the LukS-I-specific function of staphylococcal leukocidin.
Luk-I produced by Staphylococcus intermedius was found to be a new member of the staphylococcal bi-component pore-forming toxin family, in which staphylococcal leukocidin, Panton-Valentine leukocidin, and gamma-hemolysin are included. Luk-I consists of LukS-I and LukF-I. From the deduced amino acid sequence of LukS-I, a 4-residue sequence, K135K1361137S138, at the root of the stem region was found to be identical with that of the phosphorylated segment of a protein phosphorylated by protein kinase A. A mutant of LukS-I (MLSI-SA), in which the Ser138 residue was replaced by an alanine residue, was created, purified, and assayed for its leukocytolytic and pore-forming activities with LukF-I. Both LukS-I and MLSI-SA formed a ring-shaped complex with LukF-I on rabbit erythrocytes and human polymorphonuclear leukocytes (HPMNLs) membrane. However, MLSI-SA showed no leukocytolytic activity with LukF-I. LukS-I was phosphorylated by protein kinase A in the presence of [gamma-32P] ATP in a cell-free system, but MLSI-SA was not phosphorylated significantly. A potent and selective inhibitor of protein kinase A (N-[2(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H-89)) showed 50% inhibition of the Luk-I-induced cell lysis at 0.5 nM. Thus, it is concluded that the phosphorylation of the Ser138 residue in the 4-residue segment K135K1361137S138 of LukS-I is important for the leukocytolysis of HPMNLs.
Nishiyama
Akihito
A
Department of Molecular and Cell Biology, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan.
Guerra
Marie Antonette Ruth V
MA
Sugawara
Noriko
N
Yokota
Kenji
K
Kaneko
Jun
J
Kamio
Yoshiyuki
Y
D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins; D001483:Base Sequence; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D017931:DNA Primers; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D007956:Leukocidins / Q000737:chemistry* / Q000494:pharmacology; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011817:Rabbits; D017386:Sequence Homology, Amino Acid; D012694:Serine / Q000032:analysis*; D013210:Staphylococcus / Q000737:chemistry*
D001426:Bacterial Proteins; D017931:DNA Primers; D007956:Leukocidins; C108483:leukocidin S-component protein, Staphylococcus; D012694:Serine; D017868:Cyclic AMP-Dependent Protein Kinases