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Cloning and nucleotide sequence of the gene encoding the 136-kilodalton surface protein (muramidase-released protein)
H E Smith1, U Vecht, A L Gielkens
1Department of Molecular Biology, DLO-Central Veterinary Institute, Lelystad, The Netherlands.
Abstract:
We cloned and sequenced the gene encoding the muramidase-released protein (MRP) of a pathogenic Streptococcus suis type 2 strain to determine whether its amino acid sequence resembles that of proteins with known functions and to determine its function in virulence. The complete nucleotide sequence composing the gene and the regions flanking it was determined. The deduced amino acid sequence revealed the presence of a signal peptide at the N terminus and a cell envelope anchor at the C terminus, both of which resembled similar regions in several other surface proteins from gram-positive bacteria. The processed form of MRP has a length of 1,209 amino acids and a calculated molecular weight of 131,094. A highly repetitive region preceded the envelope anchor. The repeated units were preceded by a proline-rich stretch of amino acids (26 of 86). No overall homologies were observed between the amino acid sequence of MRP and protein sequences in the EMBL data bank. A particular region within the amino acid sequence, however, showed some similarity with the fibronectin-binding protein of Staphylococcus aureus. Binding of MRP to human fibronectin, however, could not be confirmed.
Insights
Researchers sequenced the muramidase-released protein (MRP) from Streptococcus suis type 2. The protein
Area of Science:
- Microbiology
- Molecular Biology
- Bacterial Pathogenesis
Background:
- Streptococcus suis type 2 is a significant pathogen.
- Understanding virulence factors is crucial for controlling infections.
Purpose of the Study:
- To clone and sequence the muramidase-released protein (MRP) gene from Streptococcus suis type 2.
- To analyze the deduced amino acid sequence of MRP for functional motifs and homologies.
- To investigate the role of MRP in bacterial virulence.
Main Methods:
- Gene cloning and nucleotide sequencing of the MRP gene and flanking regions.
- Bioinformatic analysis of the deduced amino acid sequence.
- Comparison of MRP sequence with existing protein databases (EMBL).
Main Results:
- The MRP gene sequence was determined, revealing signal peptide and cell envelope anchor motifs.
- The processed MRP is 1,209 amino acids long with a molecular weight of 131,094 Da.
- No overall homology was found, but a region showed similarity to Staphylococcus aureus fibronectin-binding protein, though binding was not confirmed.
Conclusions:
- MRP possesses structural features common to Gram-positive bacterial surface proteins.
- The function of MRP in Streptococcus suis type 2 virulence remains to be fully elucidated.
- Further research is needed to clarify the potential fibronectin-binding capability and role in pathogenesis.