Genetic Control of Fertility in Streptomyces coelicolor A3(2): the IF Fertility Type

Abstract

S U M M A R YWild-type Streptomyces coelicolor A 3(2), and many mutant and recombinant derivatives of it, are of the IF (Initial Fertility) type. At an early step in the production of recombinant strains from some of the first derivatives of A3 (2), a variant fertility type arose (NF: Normal Fertility), and subsequently IF and NF segregated within the pedigree of stock cultures. IF x IF crosses are about Ioo-fold less fertile than N F X N F or I F X N F crosses, but the clearest distinction between IF and NF is achieved by crossing with a strain of the previously described UF (Ultra-Fertile) type, when the difference in fertility approaches I ooo-fold.The IF strains give rise to UF strains with a high spontaneous frequency, and the frequency is increased by ultraviolet or X-irradiation but not appreciably by N-methyl-N'-nitro-N-nitrosoguanidine. NF strains do not give rise to UF variants with a high frequency.The difference between IF and NF is determined by a chromosomal locus near the 9 o'clock position on the linkage map. There is no evidence for the infectious conversion of one type of strain to the other in a mixed culture.In crosses with an NF strain, both IF and UF strains contribute the whole chromosome to the effective merozygotes, and the NF strain contributes the fragment, which obligatorily includes the g o'clock region. However, whereas in UF x NF crosses there is obligate inheritance of the g o'clock region of the NF genome by all sexually produced progeny, this is not true of I F X N F crosses .

Forty years of genetics with Streptomyces: from in vivo through in vitro to in silico

“…Sermonti had done so, and had begun to study the phenomenon (Sermonti & Casciano, 1963). In Glasgow, we obtained a particularly surprising result in crosses between so-called NF and UF strains (later interpreted as having an integrated SCP1 plasmid and no SCP1 respectively : Vivian & Hopwood, 1970 ;Vivian, 1971). These crosses produced recombinants so abundantly that they could be analysed non-selectively, a rare occurrence in a bacterium (Hopwood et al, 1969).…”

Mutants blocked in streptomycin production in Streptomyces griseus - the role of A-factor.

“…8,[12][13][14][15][16][17][18][19][20] Treatment of streptomycetes with acridine dyes or at high temperature frequently causes loss of various phenotypic characters with coincidental disappearance of plasmids. In S. coelicolor A3(2), the direct involvement of plasmids in the production of methylenomycin A (SCP1 plasmid) 21,22) and streptocin A, B and amrumycin (SCP2 plasmid)23) has been confirmed.…”

Giant linear plasmids in Streptomyces: a treasure trove of antibiotic biosynthetic clusters

“…In the mating with SCP1-free partners, these SCP1-integrated strains showed either a bidirectional or unidirectional gradient of transfer of genetic markers with respect to the SCP1 integration site. The integrated structures of SCP1 in an NF (normal fertility) strain 2612 32 and an NF-like strain A634 33 were analyzed. Although both strains show a bidirectional gene transfer, the direction of SCP1 insertion and the deletions at both sides of SCP1 were different.…”