Abstract
Many streptococcal strains bind to two main human blood plasma proteins: IgG and human serum albumin (HSA). Protein G expressed in group C and G streptococci has specific binding regions for these proteins. Protein G in group G streptococcal strains also contains a region binding another human plasma protein, α2-macroglobulin (α2-М), upstream to the HSA-binding domain. Two recombinant polypeptides GM and GM1 capable of binding to α2-М were obtained using the G4223 strain of a group G Streptococcus, protein G molecule of which interacts with three human blood serum proteins (IgG, HSA, and α2-М). However, polypeptide GM containing three IgG-binding and three HSA-bindings domains and the region binding α2-М has higher molecular mass and higher affinity to α2-М than polypeptide GM1 that includes only the α2-М binding region.
Keywords:
IgG-binding G protein; group G streptococci; α2-macroglobulin; α2-macroglobulin-binding polypeptide.
MeSH terms
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Amino Acid Sequence
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Bacterial Proteins / genetics
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Bacterial Proteins / metabolism*
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Binding Sites
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Cloning, Molecular
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Escherichia coli / genetics
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Escherichia coli / metabolism
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Female
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Gene Expression
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Genetic Vectors / chemistry
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Genetic Vectors / metabolism
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Humans
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Immunoglobulin G / genetics
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Immunoglobulin G / metabolism*
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Peptides / genetics
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Peptides / metabolism*
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Pregnancy
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Pregnancy-Associated alpha 2-Macroglobulins / genetics
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Pregnancy-Associated alpha 2-Macroglobulins / metabolism*
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Protein Binding
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Protein Interaction Domains and Motifs
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Recombinant Proteins / genetics
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Recombinant Proteins / metabolism
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Sequence Alignment
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Serum Albumin, Human / genetics
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Serum Albumin, Human / metabolism*
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Streptococcus / genetics
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Streptococcus / metabolism
Substances
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Bacterial Proteins
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IgG Fc-binding protein, Streptococcus
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Immunoglobulin G
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Peptides
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Pregnancy-Associated alpha 2-Macroglobulins
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Recombinant Proteins
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Serum Albumin, Human