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Sequence analysis of the cloned streptococcal cell surface antigen I/II
C Kelly1, P Evans, L Bergmeier
1Department of Immunology, United Medical School of Guy's Hospital, London, England.
FEBS Letters
|November 20, 1989
Summary
The spaP gene of Streptococcus mutans encodes a large surface antigen. Sequencing reveals conserved regions and structural features, aiding in understanding its role in serotype c.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Streptococcus mutans is a key bacterium in dental caries.
- Surface antigens play crucial roles in bacterial adhesion and virulence.
- The spaP gene encodes the Mr 185,000 surface antigen (I/II) in S. mutans serotype c.
Purpose of the Study:
- To sequence the spaP gene encoding the S. mutans serotype c surface antigen (I/II).
- To analyze the structural and conserved features of the encoded protein.
Main Methods:
- Gene sequencing of spaP (4683 bp).
- Bioinformatic analysis of the encoded protein sequence (1561 amino acids).
- N-terminal sequencing of separated antigen I and II polypeptides.
Main Results:
- The spaP gene sequence was determined.
- The encoded protein contains a signal peptide and a transmembrane domain.
- Distinct N-terminal (alanine-rich, alpha-helical) and C-terminal (proline-rich, extended structure) regions were identified.
- High conservation of the sequence was observed in S. mutans serotype c, except for a central variable region.
Conclusions:
- The complete sequence of the spaP gene provides insights into the structure of the S. mutans surface antigen I/II.
- Structural analysis reveals distinct domains with differing predicted secondary structures.
- The conserved nature of the antigen suggests functional importance in serotype c strains.