Photoinactivation of the Staphylococcus aureus Lactose-Specific EIICB Phosphotransferase Component with p-azidophenyl-ß-D-Galactoside and Phosphorylation of the Covalently Bound Substrate.
J Mol Microbiol Biotechnol
; 28(3): 147-158, 2018.
Article
em En
| MEDLINE
| ID: mdl-30522128
ABSTRACT
BACKGROUND:
The phosphoenolpyruvate (PEP)lactose phosphotransferase system of Staphylococcus aureus transports and phosphorylates lactose and various phenylgalactosides. Their phosphorylation is catalyzed by the Cys476-phosphorylated EIIB domain of the lactose-specific permease enzyme IICB (EIICBLac). Phosphorylation causes the release of galactosides bound to the EIIC domain into the cytoplasm by a mechanism not yet understood.RESULTS:
Irradiation of a reaction mixture containing the photoactivatable p-azidophenyl-ß-D-galactopyranoside and EIICBLac with UV light caused a loss of EIICBLac activity. Nevertheless, photoinactivated EIICBLac could still be phosphorylated with [32P]PEP. Proteolysis of photoinactivated [32P]P-EIICBLac with subtilisin provided an 11-kDa radioactive peptide. Only the sequence of its first three amino acids (-H-G-P-, position 245-247) could be determined. They are part of the substrate binding pocket in EIICs of the lactose/cellobiose PTS family. Surprisingly, while acid treatment caused hydrolysis of the phosphoryl group in active [32P]Pâ¼EIICBLac, photoinactivated [32P]P-EIICBLac remained strongly phosphorylated.CONCLUSION:
Phosphorylation of the -OH group at C6 of p-nitrenephenyl-ß-D-galactopyranoside covalently bound to EIICLac by the histidyl-phosphorylated [32P]Pâ¼EIIBLac domain is a likely explanation for the observed acid resistance. Placing p-nitrenephenyl-ß-D-galactopyranoside into the active site of modelled EIICLac suggested that the nitrene binds to the -NH- group of Ser248, which would explain why no sequence data beyond Pro247could be obtained.Palavras-chave
Texto completo:
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fosfotransferases
/
Staphylococcus aureus
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Sistema Fosfotransferase de Açúcar do Fosfoenolpiruvato
/
Lactose
Idioma:
En
Revista:
J Mol Microbiol Biotechnol
Assunto da revista:
BIOLOGIA MOLECULAR
/
BIOTECNOLOGIA
/
MICROBIOLOGIA
Ano de publicação:
2018
Tipo de documento:
Article
País de afiliação:
Alemanha