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Analysis of CRISPR-Cas Systems within the Bacterial Family Vibrionaceae Uncovered Significant Diversity and Evidence of Horizontal Transfer.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Analysis of CRISPR-Cas Systems within the Bacterial Family Vibrionaceae Uncovered Significant Diversity and Evidence of Horizontal Transfer./
Author:	Borowski, Joseph D.
Description:	1 online resource (161 pages)
Notes:	Source: Masters Abstracts International, Volume: 57-02.
Contained By:	Masters Abstracts International57-02(E).
Subject:	Biology. -
Online resource:	click for full text (PQDT)
ISBN:	9780355465006

Analysis of CRISPR-Cas Systems within the Bacterial Family Vibrionaceae Uncovered Significant Diversity and Evidence of Horizontal Transfer.
Borowski, Joseph D.

Analysis of CRISPR-Cas Systems within the Bacterial Family Vibrionaceae Uncovered Significant Diversity and Evidence of Horizontal Transfer. - 1 online resource (161 pages)

Source: Masters Abstracts International, Volume: 57-02.

Thesis (M.S.)

Includes bibliographical references

Clustered regulatory interspaced short palindromic repeat (CRISPR) and CRISPR associated (Cas) proteins are an immune defense system present in many bacteria and archaea species that protects against foreign DNA invasion such as phages (viruses that infect bacteria). CRISPR-Cas systems are classified based on the Cas protein content and their repeat sequence. CRISPR-Cas systems are adaptive since they acquire sequences (spacers) that act as memory from prior phage infections. To date two classes are described and at least five types are known, named Type I, II, III, IV, and V, each with a number of subtypes. Vibrio cholerae is a Gram-negative bacterium and the causative agent of the disease cholera, and only one CIRSPR-Cas system has been identified in this species. A type I-E system was found among V. cholerae classical biotype isolates, the historic cause of pandemic cholera, and is absent from biotype El Tor isolates, the cause of the present pandemic of cholera. This bacterium contains mobile genetic elements, pathogenicity islands (PAIs) and a phage, that contain the virulence factors for disease. A putative type I-F CRISPR-Cas system was identified on a 28-kb region that also contained genes for a type VI secretion system. The region integrated at the Vibrio Pathogenicity Island-1 (VPI-1) insertion site, a known marker of choleragenic isolates, in nineteen V. cholerae strains and contained the same recombination module as VPI-1. We determined that the CRISPR island excised site-specifically from the bacterial chromosome as a complete unit and the cognate integrase within the island-region was essential for this excision. These data demonstrated that identical recombination modules that catalyze integration and excision from the chromosome can acquire diverse cargo genes signifying a novel method of acquisition for CRISPR-Cas systems. Bioinformatics analysis of the VPI-6 CRISPR-Cas system was performed and showed that the CRISPR-Cas system present on VPI-6 was an active type I-F system. However, the system did not contain the canonical set of Cas proteins and appears to be a novel variant system. The distribution of CRISPR systems among V. cholerae was next examined by searching for Cas proteins homology and this analysis uncovered multiple CRISPR-Cas systems. We identified five V. cholerae strains with type I-E systems, mainly classical biotype strains and seven strains with a novel type III-B variant that contained a type I-F array, which were non-choleragenic isolates. The absence of CRISPR-Cas systems in V. cholerae El Tor isolates, the cause of the present pandemic of cholerae, is intriguing. Perhaps evolution has selected against CRISPR acquisition in these strains given that cholera toxin is present on filamentous phage and we identified many spacers that targeted these phages. We expanded our analysis to include all species within the Vibrionaceae family to determine the distribution, and diversity of systems present. From these analyses, several active CRISPR systems were identified among 45 species including type I-E, I-C, type II-B, and type III variant systems. Nearly 900 spacer sequences were identified but only 11% showed homology to known targets more than 80% of which were phages. CRISPR-Cas systems were phylogenically widespread but not highly prevalent in this group of marine organisms. This was surprising given that the marine environment is teeming with phages and probably demonstrates that this system is one of many to combat predatory phages. Many of the systems were present on genetic element and multiple systems were present within prophages. Taken together our results show that CRISPR-Cas systems are present, actively evolving, and transmitted horizontally among Vibrio species.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2018

Mode of access: World Wide Web

ISBN: 9780355465006Subjects--Topical Terms:

599573
Biology.
Index Terms--Genre/Form:

554714
Electronic books.

Analysis of CRISPR-Cas Systems within the Bacterial Family Vibrionaceae Uncovered Significant Diversity and Evidence of Horizontal Transfer.
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520 $a Clustered regulatory interspaced short palindromic repeat (CRISPR) and CRISPR associated (Cas) proteins are an immune defense system present in many bacteria and archaea species that protects against foreign DNA invasion such as phages (viruses that infect bacteria). CRISPR-Cas systems are classified based on the Cas protein content and their repeat sequence. CRISPR-Cas systems are adaptive since they acquire sequences (spacers) that act as memory from prior phage infections. To date two classes are described and at least five types are known, named Type I, II, III, IV, and V, each with a number of subtypes. Vibrio cholerae is a Gram-negative bacterium and the causative agent of the disease cholera, and only one CIRSPR-Cas system has been identified in this species. A type I-E system was found among V. cholerae classical biotype isolates, the historic cause of pandemic cholera, and is absent from biotype El Tor isolates, the cause of the present pandemic of cholera. This bacterium contains mobile genetic elements, pathogenicity islands (PAIs) and a phage, that contain the virulence factors for disease. A putative type I-F CRISPR-Cas system was identified on a 28-kb region that also contained genes for a type VI secretion system. The region integrated at the Vibrio Pathogenicity Island-1 (VPI-1) insertion site, a known marker of choleragenic isolates, in nineteen V. cholerae strains and contained the same recombination module as VPI-1. We determined that the CRISPR island excised site-specifically from the bacterial chromosome as a complete unit and the cognate integrase within the island-region was essential for this excision. These data demonstrated that identical recombination modules that catalyze integration and excision from the chromosome can acquire diverse cargo genes signifying a novel method of acquisition for CRISPR-Cas systems. Bioinformatics analysis of the VPI-6 CRISPR-Cas system was performed and showed that the CRISPR-Cas system present on VPI-6 was an active type I-F system. However, the system did not contain the canonical set of Cas proteins and appears to be a novel variant system. The distribution of CRISPR systems among V. cholerae was next examined by searching for Cas proteins homology and this analysis uncovered multiple CRISPR-Cas systems. We identified five V. cholerae strains with type I-E systems, mainly classical biotype strains and seven strains with a novel type III-B variant that contained a type I-F array, which were non-choleragenic isolates. The absence of CRISPR-Cas systems in V. cholerae El Tor isolates, the cause of the present pandemic of cholerae, is intriguing. Perhaps evolution has selected against CRISPR acquisition in these strains given that cholera toxin is present on filamentous phage and we identified many spacers that targeted these phages. We expanded our analysis to include all species within the Vibrionaceae family to determine the distribution, and diversity of systems present. From these analyses, several active CRISPR systems were identified among 45 species including type I-E, I-C, type II-B, and type III variant systems. Nearly 900 spacer sequences were identified but only 11% showed homology to known targets more than 80% of which were phages. CRISPR-Cas systems were phylogenically widespread but not highly prevalent in this group of marine organisms. This was surprising given that the marine environment is teeming with phages and probably demonstrates that this system is one of many to combat predatory phages. Many of the systems were present on genetic element and multiple systems were present within prophages. Taken together our results show that CRISPR-Cas systems are present, actively evolving, and transmitted horizontally among Vibrio species.
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