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Sequence of pilin from Bacteroides nodosus 351 (Serogroup H) and implications for serogroup classification
P A Hoyne1, T C Elleman, N M McKern
1Division of Biotechnology, Commonwealth Scientific and Industrial Research Organization, Parkville, Australia.
Abstract:
The nucleotide sequence of the pilin gene from Bacteroides nodosus strain 351, currently classified as serogroup H, subgroup 2 (H2) has been determined. The gene encodes a single polypeptide (prepilin) of 160 amino acids and Mr 17,150. However, pilin isolated from B. nodosus 351 migrates as two distinct bands in sodium dodecyl sulphate-polyacrylamide gel electrophoresis, due to an internal peptide bond cleavage. Amino acid sequence studies of pilin from B. nodosus 351 have established that the cleavage occurs between 72Ala and 73Ser of the mature protein sequence. Comparisons of gene and amino acid sequences of pilin from B. nodosus 351 with the corresponding sequences from strains of serogroups D and H1 indicate that these sequences share a close relationship. However, the level of sequence identity between B. nodosus 351 pilin and pilin from strain 265 of serogroup H1 is lower than anticipated for strains within a serogroup and suggests that B. nodosus 265 and B. nodosus 351 should not be classified within the same serogroup.
Insights
The pilin gene sequence from Bacteroides nodosus strain 351 was determined. Sequence analysis suggests strain 351 and strain 265 should not be in the same serogroup due to low sequence identity.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Bacteroides nodosus causes ovine footrot.
- Pilin proteins are key virulence factors and serogroup determinants.
- Strain 351 is classified as serogroup H, subgroup 2 (H2).
Purpose of the Study:
- To determine the nucleotide sequence of the pilin gene from Bacteroides nodosus strain 351.
- To compare pilin gene and amino acid sequences with other B. nodosus strains.
- To re-evaluate serogroup classification based on sequence data.
Main Methods:
- Nucleotide sequencing of the pilin gene.
- Analysis of the encoded prepilin and mature pilin sequences.
- Amino acid sequence comparison using bioinformatics tools.
Main Results:
- The pilin gene encodes a 160-amino acid prepilin (Mr 17,150).
- Internal peptide bond cleavage occurs between 72Ala and 73Ser in mature pilin.
- Sequence identity between strain 351 and H1 strain 265 pilin is lower than expected for strains within the same serogroup.
Conclusions:
- The pilin gene sequence provides insights into B. nodosus H2 strain 351.
- Sequence divergence suggests that B. nodosus strains 351 (H2) and 265 (H1) should not be classified within the same serogroup.
- Pilin sequence analysis is a valuable tool for bacterial taxonomy and strain differentiation.