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Genomic and physiological variability within Group II (non-proteolytic) Clostridium botulinum.

Stringer SC, Carter AT, Webb MD, Wachnicka E, Crossman LC, Sebaihia M, Peck MW - BMC Genomics (2013)

Bottom Line: These results were compared with characteristics determined from physiological tests.However, these two subsets did not differ strongly in minimum growth temperature or maximum NaCl concentration for growth.No relationship was found between tellurite resistance and toxin type despite all the tested type B and type F strains carrying tehB, while the sequence was absent or diverged in all type E strains.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Food Research (IFR), Norwich Research Park, Colney, Norwich NR4 7UA, UK. sandra.stringer@ifr.ac.uk

ABSTRACT

Background: Clostridium botulinum is a group of four physiologically and phylogenetically distinct bacteria that produce botulinum neurotoxin. While studies have characterised variability between strains of Group I (proteolytic) C. botulinum, the genetic and physiological variability and relationships between strains within Group II (non-proteolytic) C. botulinum are not well understood. In this study the genome of Group II strain C. botulinum Eklund 17B (NRP) was sequenced and used to construct a whole genome DNA microarray. This was used in a comparative genomic indexing study to compare the relatedness of 43 strains of Group II C. botulinum (14 type B, 24 type E and 5 type F). These results were compared with characteristics determined from physiological tests.

Results: Whole genome indexing showed that strains of Group II C. botulinum isolated from a wide variety of environments over more than 75 years clustered together indicating the genetic background of Group II C. botulinum is stable. Further analysis showed that strains forming type B or type F toxin are closely related with only toxin cluster genes targets being unique to either type. Strains producing type E toxin formed a separate subset. Carbohydrate fermentation tests supported the observation that type B and F strains form a separate subset to type E strains. All the type F strains and most of type B strains produced acid from amylopectin, amylose and glycogen whereas type E strains did not. However, these two subsets did not differ strongly in minimum growth temperature or maximum NaCl concentration for growth. No relationship was found between tellurite resistance and toxin type despite all the tested type B and type F strains carrying tehB, while the sequence was absent or diverged in all type E strains.

Conclusions: Although Group II C. botulinum form a tight genetic group, genomic and physiological analysis indicates there are two distinct subsets within this group. All type B strains and type F strains are in one subset and all type E strains in the other.

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Organisation of the botulinum neurotoxin clusters of Group II C. botulinum Eklund 17B (NRP) and Alaska E43.C. botulinum neurotoxin genes (bont) are located with other associated proteins in one of two types of cluster arrangement. In Group II C. botulinum all published type B neurotoxin genes are in a ha cluster and all type E and type F neurotoxin genes are in an orfX cluster. Eklund 17B and Alaska E43 show typical cluster organisation. A. The neurotoxin gene of Group II C. botulinum type B strain Eklund 17B (NRP) is in a ha cluster located on a plasmid, CDS numbers CB17B_P047 to CB17B_P052. B. The published sequence of Group II C. botulinum type E strain Alaska E43 (accession number NC_010723) shows that the neurotoxin gene is located on the chromosome in an orfX cluster, CDS CLH_1110 to CLH_1115.
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Figure 4: Organisation of the botulinum neurotoxin clusters of Group II C. botulinum Eklund 17B (NRP) and Alaska E43.C. botulinum neurotoxin genes (bont) are located with other associated proteins in one of two types of cluster arrangement. In Group II C. botulinum all published type B neurotoxin genes are in a ha cluster and all type E and type F neurotoxin genes are in an orfX cluster. Eklund 17B and Alaska E43 show typical cluster organisation. A. The neurotoxin gene of Group II C. botulinum type B strain Eklund 17B (NRP) is in a ha cluster located on a plasmid, CDS numbers CB17B_P047 to CB17B_P052. B. The published sequence of Group II C. botulinum type E strain Alaska E43 (accession number NC_010723) shows that the neurotoxin gene is located on the chromosome in an orfX cluster, CDS CLH_1110 to CLH_1115.

Mentions: The genome of Eklund 17B (NRP) includes one plasmid which carries the genes of the toxin cluster. The plasmid features are described Figure 3. There are two conserved botulinum neurotoxin cluster types, the ha cluster and the orfX cluster [1]. The toxin gene clusters from Group II C.botulinum type B strain Eklund 17B (NRP) and type E strain Alaska E43 (accession number NC_010723) are shown in Figure 4 illustrating the typical organisation of the ha cluster and orfX cluster types respectively. The toxin gene of C.botulinum Eklund 17B (NRP) is in a ha cluster that sits adjacent to a resolvase-recombinase that may be significant in the lateral gene transfer of this cluster to alternative plasmid and chromosomal locations. Specific features of the plasmid include plasmid replication and maintenance CDSs and several conserved hypothetical CDSs of similar length. BLAST analysis shows that, for the most part, these CDSs only show significant sequence similarity to the equivalent genes from Eklund 17B (JGI). These CDSs do not show any conserved Pfam domain features or predicted transmembrane domains. Repeat analysis using the program REPuter [16] does not indicate that these genetic regions are highly repetitive, although repeats are detectable on the plasmid.


Genomic and physiological variability within Group II (non-proteolytic) Clostridium botulinum.

Stringer SC, Carter AT, Webb MD, Wachnicka E, Crossman LC, Sebaihia M, Peck MW - BMC Genomics (2013)

Organisation of the botulinum neurotoxin clusters of Group II C. botulinum Eklund 17B (NRP) and Alaska E43.C. botulinum neurotoxin genes (bont) are located with other associated proteins in one of two types of cluster arrangement. In Group II C. botulinum all published type B neurotoxin genes are in a ha cluster and all type E and type F neurotoxin genes are in an orfX cluster. Eklund 17B and Alaska E43 show typical cluster organisation. A. The neurotoxin gene of Group II C. botulinum type B strain Eklund 17B (NRP) is in a ha cluster located on a plasmid, CDS numbers CB17B_P047 to CB17B_P052. B. The published sequence of Group II C. botulinum type E strain Alaska E43 (accession number NC_010723) shows that the neurotoxin gene is located on the chromosome in an orfX cluster, CDS CLH_1110 to CLH_1115.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3672017&req=5

Figure 4: Organisation of the botulinum neurotoxin clusters of Group II C. botulinum Eklund 17B (NRP) and Alaska E43.C. botulinum neurotoxin genes (bont) are located with other associated proteins in one of two types of cluster arrangement. In Group II C. botulinum all published type B neurotoxin genes are in a ha cluster and all type E and type F neurotoxin genes are in an orfX cluster. Eklund 17B and Alaska E43 show typical cluster organisation. A. The neurotoxin gene of Group II C. botulinum type B strain Eklund 17B (NRP) is in a ha cluster located on a plasmid, CDS numbers CB17B_P047 to CB17B_P052. B. The published sequence of Group II C. botulinum type E strain Alaska E43 (accession number NC_010723) shows that the neurotoxin gene is located on the chromosome in an orfX cluster, CDS CLH_1110 to CLH_1115.
Mentions: The genome of Eklund 17B (NRP) includes one plasmid which carries the genes of the toxin cluster. The plasmid features are described Figure 3. There are two conserved botulinum neurotoxin cluster types, the ha cluster and the orfX cluster [1]. The toxin gene clusters from Group II C.botulinum type B strain Eklund 17B (NRP) and type E strain Alaska E43 (accession number NC_010723) are shown in Figure 4 illustrating the typical organisation of the ha cluster and orfX cluster types respectively. The toxin gene of C.botulinum Eklund 17B (NRP) is in a ha cluster that sits adjacent to a resolvase-recombinase that may be significant in the lateral gene transfer of this cluster to alternative plasmid and chromosomal locations. Specific features of the plasmid include plasmid replication and maintenance CDSs and several conserved hypothetical CDSs of similar length. BLAST analysis shows that, for the most part, these CDSs only show significant sequence similarity to the equivalent genes from Eklund 17B (JGI). These CDSs do not show any conserved Pfam domain features or predicted transmembrane domains. Repeat analysis using the program REPuter [16] does not indicate that these genetic regions are highly repetitive, although repeats are detectable on the plasmid.

Bottom Line: These results were compared with characteristics determined from physiological tests.However, these two subsets did not differ strongly in minimum growth temperature or maximum NaCl concentration for growth.No relationship was found between tellurite resistance and toxin type despite all the tested type B and type F strains carrying tehB, while the sequence was absent or diverged in all type E strains.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Food Research (IFR), Norwich Research Park, Colney, Norwich NR4 7UA, UK. sandra.stringer@ifr.ac.uk

ABSTRACT

Background: Clostridium botulinum is a group of four physiologically and phylogenetically distinct bacteria that produce botulinum neurotoxin. While studies have characterised variability between strains of Group I (proteolytic) C. botulinum, the genetic and physiological variability and relationships between strains within Group II (non-proteolytic) C. botulinum are not well understood. In this study the genome of Group II strain C. botulinum Eklund 17B (NRP) was sequenced and used to construct a whole genome DNA microarray. This was used in a comparative genomic indexing study to compare the relatedness of 43 strains of Group II C. botulinum (14 type B, 24 type E and 5 type F). These results were compared with characteristics determined from physiological tests.

Results: Whole genome indexing showed that strains of Group II C. botulinum isolated from a wide variety of environments over more than 75 years clustered together indicating the genetic background of Group II C. botulinum is stable. Further analysis showed that strains forming type B or type F toxin are closely related with only toxin cluster genes targets being unique to either type. Strains producing type E toxin formed a separate subset. Carbohydrate fermentation tests supported the observation that type B and F strains form a separate subset to type E strains. All the type F strains and most of type B strains produced acid from amylopectin, amylose and glycogen whereas type E strains did not. However, these two subsets did not differ strongly in minimum growth temperature or maximum NaCl concentration for growth. No relationship was found between tellurite resistance and toxin type despite all the tested type B and type F strains carrying tehB, while the sequence was absent or diverged in all type E strains.

Conclusions: Although Group II C. botulinum form a tight genetic group, genomic and physiological analysis indicates there are two distinct subsets within this group. All type B strains and type F strains are in one subset and all type E strains in the other.

Show MeSH
Related in: MedlinePlus