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The group A streptococcal M-type 3 protein gene exhibits a C terminus typical for class I M proteins
A Podbielski1, R Baird, A Kaufhold
1Institute of Medical Microbiology, Technical University (RWTH), Aachen, Federal Republic of Germany.
Abstract:
The M protein gene (emm gene) from a reference group A streptococcal strain of serotype M3 was amplified by the polymerase chain reaction and partially sequenced. Hybridization assays using an oligonucleotide probe derived from the N-terminal sequence revealed that this gene segment is highly homologous among M-type 3 isolates. Of note, analysis of the nucleotide sequence data from the C terminus of the gene confirmed that the emm 3 gene exhibited all the features characteristic for group A streptococcal M-class I molecules. Recently published sequence data that were assigned to emm 3 resulted from a strain confusion and were shown to be the first one derived from an emm gene of an M-untypable isolate.
Insights
The M protein gene (emm gene) from M3 Streptococcus pyogenes was sequenced, revealing high homology among isolates. This confirms emm3 as a Group A Streptococcus M-class I molecule, distinct from previous misidentified sequences.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Group A Streptococcus (GAS) causes various infections.
- M protein is a key virulence factor and basis for serotyping.
- Accurate identification of M protein genes (emm) is crucial for understanding GAS epidemiology.
Purpose of the Study:
- To characterize the emm gene of the M3 serotype of Group A Streptococcus.
- To confirm the classification of the emm3 gene within M-class I molecules.
- To clarify discrepancies with previously published emm3 sequence data.
Main Methods:
- Polymerase chain reaction (PCR) amplification of the emm gene from an M3 reference strain.
- Partial sequencing of the amplified emm gene.
- Oligonucleotide probe hybridization assays for sequence homology analysis.
- Nucleotide sequence analysis of the C-terminus.
Main Results:
- The emm gene from the M3 reference strain was successfully amplified and partially sequenced.
- Hybridization assays demonstrated high sequence homology of the N-terminal region among M3 isolates.
- Sequence analysis confirmed the emm3 gene possesses characteristics of M-class I molecules.
- Previously published emm3 sequences were attributed to an M-untypable isolate due to strain confusion.
Conclusions:
- The emm3 gene sequence from the reference M3 strain is confirmed as a distinct M-class I molecule.
- The study clarifies and corrects erroneous previous emm3 sequence data.
- Accurate emm gene sequencing is vital for correct bacterial strain identification and epidemiological studies.