Streptomyces plasmid and culture

Details Streptomyces plasmid and culture Streptomyces plasmid and culture

1980-01-24

1982-11-23

Tanenholtz, Alvin E.

Chemistry: molecular biology and microbiology

Micro-organism, per se ; compositions thereof; proces of...

Bacteria or actinomycetales; media therefor

435172, 435317, 435261, 435 34, C12N 120, C12N 1500, C12N 100, C12N 102, C12Q 104

Patent

active

043605974

DESCRIPTION:

BRIEF SUMMARY
This invention relates to the incorporation of nucleic acid into cellular systems, to vectors for effecting such incorporation and to micro-organisms containing such vectors.
Methods for the incorporation of foreign nucleic acid into cellular systems have recently received much attention, the resultant modified cells being of interest either as a means of producing the foreign nucleic acid through replication of the cells or through the imparting of valuable properties to the cells by virtue of the presence of the foreign nucleic acid therein.
Much of the previous work in this area has involved the use of Escherichia coli as the host cellular system for the foreign nucleic acid but we have turned our attention instead to the genus Streptomyces and related genera, and have identified a novel group of plasmids of particular value as vectors for use with such micro-organisms.
Accordingly the present invention comprises a Streptomyces plasmid which has the characteristic that its presence in non-integrated form in a micro-organism of the species Streptomyces lividans confers on that micro-organism the properties (a) of forming "pocks" when grown on a "lawn" of that strain of micro-organism deposited with the National Collection of Industrial Bacteria (NCIB) under the reference number 11416, and (b) of not forming "pocks" when grown on a "lawn" of that strain of micro-organism deposited with the NCIB under the reference number 11417, or which is derivable from a plasmid having such a characteristic by the removal or addition of DNA therefrom.
Plasmids having the characteristic defined above constitute a related family isolable as covalently closed circular (ccc) DNA which possess a portion of their DNA sequence in common and thereby possess certain common properties throughout the family. The properties include the formation of "pocks" when a micro-organism of the species S. lividans containing a plasmid of this family in non-integrated form is grown on a "lawn" of the micro-organism NCIB 11416. The term "lawn" is employed herein, as in common usage, to indicate a confluent culture. The term "pocks" indicates foci of inhibition of growth of the cells constituting the lawn resulting from inhibition by the cells growing thereon; this phenomenon also being referred to as "tramlining" in relation to larger areas of inhibition. Such inhibition is believed to be analogous to the lethal zygosis described in the case of E. coli, being hereinafter referred to in this way, and is believed to result from a transfer of the plasmid into the cells forming the lawn from those growing on it.
The micro-organism NCIB 11416 is a strain of S. lividans which will function as a passive partner against which strains containing a non-integrated plasmid of this family will express lethal zygosis. This is believed to be because in NCIB 11416 a plasmid of this family capable of functional expression is absent although the strain is believed to contain such a plasmid in a form in which it is not expressible, presumably due to some type of integration. In contrast, the micro-organism NCIB 11417 is a strain of S. lividans which contains a plasmid of the family in non-integrated form and functionally expressible form. The presence of such a plasmid not only confers resistance against lethal zygosis initiated by a strain of S. lividans containing that plasmid but it has also been found that the inter-relation between plasmids of this family is such that lethal zygosis does not occur when a strain of S. lividans containing a plasmid of the family is grown on a lawn of a strain containing that plasmid or any other plasmid of the family in functionally expressible form.
It will be appreciated that the present invention extends to plasmids as defined above in isolated form, i.e. when not present in a micro-organism, or when present in a micro-organism. The invention thus includes a micro-organism containing such a plasmid. Also included by the invention is a culture system comprising a micro-organism containing a plasmid as defined herein togethe

REFERENCES:
Huber et al., Can. J. Microbiol., vol. 24, pp. 631 & 632, (1978).
Broda et al., Plasmids, pp. 4-11, W. H. Freeman and Co., Oxford and San Francisco, 1979.
Hopwood et al., "Genetic Recombination Through Protoplast Fusion in Streptomyces", Nature, 268, 171-174, (1977).
Hopwood, "Opening Address--The Many Faces of Recombination", Genetics of Industrial Microorganisms.
Bibb et al., "Transformation of Plasmid DNA Into Streptomyces at High Frequency", Nature, 274, 398-400, (1978).

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