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Applied and Environmental Microbiology, September 2000, p. 3856-3867, Vol. 66, No. 9
Departments of Chemical
Engineering1 and
Microbiology,2 University of
Washington, Seattle, Washington 98195-1750
Received 10 April 2000/Accepted 8 June 2000
The nucleotide sequence of a 12-kb fragment of the cryptic
Deinococcus radiodurans SARK plasmid pUE10 was determined,
in order to direct the development of small, versatile cloning systems for Deinococcus. Annotation of the sequence revealed 12 possible open reading frames. Among these are the repU and
resU genes, the predicted products of which share
similarity with replication proteins and site-specific resolvases,
respectively. The products of both genes were demonstrated using an
overexpression system in Escherichia coli. RepU was found
to be required for replication, and ResU was found to be required for
stable maintenance of pUE10 derivatives. Gel shift analysis using
purified His-tagged RepU identified putative binding sites and
suggested that RepU may be involved in both replication initiation and
autoregulation of repU expression. In addition, a gene
encoding a possible antirestriction protein was found, which was shown
to be required for high transformation frequencies. The arrangement of
the replication region and putative replication genes for this plasmid
from D. radiodurans strain SARK is similar to that for
plasmids found in Thermus but not to that for the 45.7-kb
plasmid found in D. radiodurans strain R1. The minimal
region required for autonomous replication in D. radiodurans was determined by sequential deletion of segments from the 12-kb fragment. The resulting minimal replicon, which consists
of approximately 2.6 kb, was used for the construction of a shuttle
vector for E. coli and D. radiodurans. This
vector, pRAD1, is a convenient general-purpose cloning vector. In
addition, pRAD1 was used to generate a promoter probe vector, and a
plasmid containing lacZ and a Deinococcus
promoter was shown to efficiently express LacZ.
0099-2240/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Characterization of the Minimal Replicon of a
Cryptic Deinococcus radiodurans SARK Plasmid and Development
of Versatile Escherichia coli-D. radiodurans Shuttle
Vectors
*
Corresponding author. Mailing address: Department of
Chemical Engineering, Box 351750, University of Washington,
Seattle, WA 98195-1750. Phone: (206) 616-5282. Fax:
(206) 616-5721. E-mail: lidstrom{at}u.washington.edu.
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