ISSN:
1432-072X
Keywords:
Cyanobacteria
;
DNA restriction and cloning
;
Gene fusions
;
Leucine biosynthesis
;
Mutant complementation
;
Nostoc
;
Transcription
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Genomic DNA extracted from the symbiotically-competent, heterocyst-forming cyanobacterium Nostoc sp. strain 7801 was resistant to cleavage by a number of restriction endonucleases. A cosmid library of Nostoc DNA was prepared and maintained in the modification-limited Escherichia coli strain HB101. Analysis of cloned Nostoc DNA fragments indicated infrequent occurrence of restriction endonuclease recognition sites in the Nostoc genome. The Nostoc genomic library was screened for sequences complementing mutations in the E. coli leucine and proline biosynthetic operons. Two cosmids complementing leuB were isolated but none for leuA, leuC, leuD, or proA were detected in 1000 cosmids. A 3.0 kb fragment subcloned from one of the cosmids complemented mutations in leuB when inserted into the HindIII site of pBR322 in either orientation, demonstrating that transcription of leuB originated within the cloned fragment. The cloned fragment also carries a second site capable of initiating transcription of fused antibiotic resistance genes. While transcription of Nostoc DNA sequences did occur in E. coli, unknown barriers must also exist that prevented additional biological complementation of specific E. coli mutations.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00470864
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