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ISL2, a new mobile genetic element in Lactobacillus helveticus
1Nestlé Research Center, Nestec Ltd., Lausanne, Switzerland.
Molecular & General Genetics : MGG
|November 1, 1994
Summary
A novel mobile genetic element, ISL2, was discovered in Lactobacillus helveticus, causing mutations in beta-galactosidase genes. This element
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Spontaneous mutations in Lactobacillus helveticus can affect bacterial physiology.
- Understanding the genetic basis of these mutations is crucial for strain characterization.
Purpose of the Study:
- To identify and analyze the causes of spontaneous mutations in the beta-galactosidase locus of Lactobacillus helveticus.
- To characterize a newly identified insertion sequence (IS) element responsible for these mutations.
Main Methods:
- Analysis of spontaneous mutations at the beta-galactosidase locus (lacL-lacM) in Lactobacillus helveticus.
- Identification and sequencing of the novel insertion sequence element, ISL2.
- Comparative genomic analysis to determine ISL2 distribution and copy number.
Main Results:
- A significant proportion of mutations were attributed to the insertion of a new IS element, ISL2, into the lac genes.
- ISL2 is an 858 bp element with 16-bp inverted repeats, generating 3-bp target duplications. It possesses an open reading frame homologous to transposases.
- ISL2 exists in 4-21 copies in the L. helveticus genome and is absent in other lactic acid bacteria.
Conclusions:
- ISL2 is a novel mobile genetic element in Lactobacillus helveticus that drives mutations in essential genes.
- The variable copy number and genomic location of ISL2 across different strains offer potential for Lactobacillus helveticus strain identification and genetic fingerprinting.