Articles
ERWINIA AMYLOVORA CRISPR ELEMENTS PROVIDE NEW TOOLS FOR EVALUATING DIVERSITY AND MICROBIAL SOURCE TRACKING
Article number
896_11
Pages
99 – 107
Language
English
Abstract
CRISPR (clustered regularly interspaced short palindrome repeats) arrays consist of direct repeating units interspersed with similarly-sized non repetitive spacers and are thought to mediate immunity against extra-chromosomal agents and limit horizontal gene transfer in prokaryotes through a proposed RNA-interference-like mechanism.
Spacers are derived from sequences of preexisting transmissible genetic elements such as bacteriophages or conjugative plasmids and are presumably acquired during exposure to these elements.
The number of CRISPR arrays in a bacterial chromosome is variable, and the content of each array can also differ in both repeat number and in the presence or absence of specific spacers.
This variability provides a historical record or genetic footprint of a bacterial strain that is potentially reflective of a specific geographic region or host environment and may provide insight into the diversity of E. amylovora strains and assist in the genetic tracking of individuals.
Forty-five strains varying in geographic location of isolation (from within Michigan and throughout the United States, Europe, and the Middle East), host range, plasmid content, and streptomycin sensitivity were evaluated for CRISPR array number and spacer variability.
The CRISPR repeat sequence among E. amylovora strains consists of 29 bp and is universal despite host range, geographic distribution, or array number, and nearly identical to those found in E. pyrifoliae CRISPR 1 and 2 but not 3 and 4. A total of 357 unique spacers have been identified to date in CRISPR arrays present in E. amylovora. Spacer patterns from Michigan strains were mainly distinct from strains isolated in the western US, although strains from France and Lebanon included in the study shared the same patterns as some strains from Michigan.
Spacer sequence identities to foreign genetic elements included plasmids from E. tasmaniensis and Salmonella enterica.
Spacers are derived from sequences of preexisting transmissible genetic elements such as bacteriophages or conjugative plasmids and are presumably acquired during exposure to these elements.
The number of CRISPR arrays in a bacterial chromosome is variable, and the content of each array can also differ in both repeat number and in the presence or absence of specific spacers.
This variability provides a historical record or genetic footprint of a bacterial strain that is potentially reflective of a specific geographic region or host environment and may provide insight into the diversity of E. amylovora strains and assist in the genetic tracking of individuals.
Forty-five strains varying in geographic location of isolation (from within Michigan and throughout the United States, Europe, and the Middle East), host range, plasmid content, and streptomycin sensitivity were evaluated for CRISPR array number and spacer variability.
The CRISPR repeat sequence among E. amylovora strains consists of 29 bp and is universal despite host range, geographic distribution, or array number, and nearly identical to those found in E. pyrifoliae CRISPR 1 and 2 but not 3 and 4. A total of 357 unique spacers have been identified to date in CRISPR arrays present in E. amylovora. Spacer patterns from Michigan strains were mainly distinct from strains isolated in the western US, although strains from France and Lebanon included in the study shared the same patterns as some strains from Michigan.
Spacer sequence identities to foreign genetic elements included plasmids from E. tasmaniensis and Salmonella enterica.
Publication
Authors
G.C. McGhee, G.W. Sundin
Keywords
genetic diversity, streptomycin resistance
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