Leptospira genomes are modified at 5'-GTAC

Ralph, David; Que, Quideng; Etten, James L. Van; McClelland, Michael

doi:10.1128/jb.175.12.3913-3915.1993

Cited by 2 publications

(1 citation statement)

References 32 publications

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“…We found no evidence that any of the other potential restriction sites mentioned by Rocha and colleagues (49) could be blocked by BBQ67 or BBE02 modification (data not shown). Modification of GTAC sequences has been reported in another spirochete, Leptospira (46).…”

Section: Discussionmentioning

confidence: 99%

Defining the Plasmid-Borne Restriction-Modification Systems of the Lyme Disease SpirocheteBorrelia burgdorferi

2011

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The restriction-modification (R-M) systems of many bacteria present a barrier to the stable introduction of foreign DNA. The Lyme disease spirochete Borrelia burgdorferi has two plasmid-borne putative R-M genes, bbe02 and bbq67, whose presence limits transformation by shuttle vector DNA from Escherichia coli. We show that both the bbe02 and bbq67 loci in recipient B. burgdorferi limit transformation with shuttle vector DNA from E. coli, irrespective of its dam, dcm, or hsd methylation status. However, plasmid DNA purified from B. burgdorferi transformed naïve B. burgdorferi much more efficiently than plasmid DNA from E. coli, particularly when the bbe02 and bbq67 genotypes of the B. burgdorferi DNA source matched those of the recipient. We detected adenine methylation of plasmid DNA prepared from B. burgdorferi that carried bbe02 and bbq67. These results indicate that the bbe02 and bbq67 loci of B. burgdorferi encode distinct R-M enzymes that methylate endogenous DNA and cleave foreign DNA lacking the same sequence-specific modification. Our findings have basic implications for horizontal gene transfer among B. burgdorferi strains with distinct plasmid contents. Further characterization and identification of the nucleotide sequences recognized by BBE02 and BBQ67 will facilitate efficient genetic manipulation of this pathogenic spirochete.Borrelia burgdorferi sensu lato is a zoonotic pathogen whose natural infectious cycle alternates between a tick vector and rodent or bird reservoir hosts (1,7,8,14,32,33,36). Transmission of B. burgdorferi to humans occurs through the bite of an infected tick and can lead to Lyme disease, which is a major public health concern in areas of North America and Europe where B. burgdorferi is endemic (8, 53).The genomic structure of the spirochete B. burgdorferi is unique, consisting of a linear chromosome of approximately 900 kb and more than 20 linear (lp) and circular (cp) plasmids, ranging in size from ϳ5 kb to 56 kb, in the type strain B31 (9,10,11,19,42). The plasmids of B. burgdorferi are present at unit copy number relative to the chromosome (22), and some are relatively unstable during in vitro propagation (52, 57). The loss of linear plasmids lp25, lp28-1, and lp36 by strain B31 was found to correlate with the loss of infectivity in mice (20,31,45,56), leading to the identification of genes carried on these plasmids that are dispensable in vitro but required in vivo during an experimental infectious cycle (21,26,35,44,47). The loss of two linear plasmids, lp25 and lp56, was shown to correlate with enhanced shuttle vector transformation, suggesting that specific lp25 and lp56 gene products present a barrier to stable introduction of foreign DNA (34). Further studies linked the transformation phenotype of B. burgdorferi strain B31 with the bbe02 and bbq67 genes on lp25 and lp56, respectively, and the putative restriction-modification (R-M) enzymes that they encode (11,27,29,34). The recent demonstration by Chen and colleagues of enhanced transformation of B. burgdorferi follow...

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Section: Discussionmentioning

confidence: 99%