Complete sequence analysis of novel plasmids from emetic and periodontal Bacillus cereus isolates reveals a common evolutionary history among the B. cereus-group plasmids, including Bacillus anthracis pXO1.
The plasmids of the members of the Bacillus cereus sensu lato group of organisms are essential in defining the phenotypic traits associated with pathogenesis and ecology. For example, Bacillus anthracis contains two plasmids, pXO1 and pXO2, encoding toxin production and encapsulation, respectively, that define this species pathogenic potential, whereas the presence of a Bt toxin-encoding plasmid defines Bacillus thuringiensis isolates. In this study the plasmids from B. cereus isolates that produce emetic toxin or are linked to periodontal disease were sequenced and analyzed. Two periodontal isolates examined contained almost identical approximately 272-kb plasmids, named pPER272. The emetic toxin-producing isolate contained one approximately 270-kb plasmid, named pCER270, encoding the cereulide biosynthesis gene cluster. Comparative sequence analyses of these B. cereus plasmids revealed a high degree of sequence similarity to the B. anthracis pXO1 plasmid, especially in a putative replication region. These plasmids form a newly defined group of pXO1-like plasmids. However, these novel plasmids do not contain the pXO1 pathogenicity island, which in each instance is replaced by plasmid specific DNA. Plasmids pCER270 and pPER272 share regions that are not found in any other pXO1-like plasmids. Evolutionary studies suggest that these plasmids are more closely related to each other than to other identified B. cereus plasmids. Screening of a population of B. cereus group isolates revealed that pXO1-like plasmids are more often found in association with clinical isolates. This study demonstrates that the pXO1-like plasmids may define pathogenic B. cereus isolates in the same way that pXO1 and pXO2 define the B. anthracis species.
Rasko
David A
DA
The Institute for Genomic Research, 9712 Medical Center Drive, Rockville, Maryland 20850, USA. david.rasko@utsouthwestern.edu
Rosovitz
M J
MJ
Økstad
Ole Andreas
OA
Fouts
Derrick E
DE
Jiang
Lingxia
L
Cer
Regina Z
RZ
Kolstø
Anne-Brit
AB
Gill
Steven R
SR
Ravel
Jacques
J
D000595:Amino Acid Sequence; D001408:Bacillus anthracis / Q000235:genetics*; D001409:Bacillus cereus / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics; D001427:Bacterial Toxins / Q000096:biosynthesis / Q000235:genetics*; D001483:Base Sequence; D005075:Biological Evolution; D047630:Depsipeptides / Q000235:genetics; D005798:Genes, Bacterial; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology*; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D005810:Multigene Family; D010518:Periodontitis / Q000382:microbiology*; D010957:Plasmids / Q000737:chemistry / Q000235:genetics*; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity
D001426:Bacterial Proteins; D001427:Bacterial Toxins; D047630:Depsipeptides; C089294:cereulide