Structure of peptostreptococcal protein L and identification of a repeated immunoglobulin light chain-binding domain.

摘要: The gene for protein L, an immunoglobulin (Ig) light chain-binding expressed by some strains of the anaerobic bacterial species Peptostreptococcus magnus, was cloned and sequenced. translates into a 719 amino acid residues. Following signal sequence 18 acids NH2-terminal region ("A") 79 residues, molecule contains five homologous "B" repeats 72-76 each. Further, toward COOH terminus, two additional ("C") were found. These are not related to repeats, but highly each other. After C (52 each), hydrophilic, proline-rich putative cell wall-spanning ("W") found, followed at COOH-terminal end hydrophobic membrane anchor ("M"). Fragments expressed, corresponding peptides analyzed Ig-binding activity. B found be responsible interaction with Ig chains. An Escherichia coli high level expression system adapted production large amounts L fragments comprising one four respectively.