Oh. Martinezcosta et al., A RELA SPOT HOMOLOGOUS GENE FROM STREPTOMYCES-COELICOLOR A3(2) CONTROLS ANTIBIOTIC BIOSYNTHETIC GENES/, The Journal of biological chemistry, 271(18), 1996, pp. 10627-10634
A 0.972-kilobase pair DNA fragment from Streptomyces lividans that ind
uces the production of the blue-pigmented antibiotic actinorhodine in
S, lividans when cloned on a multicopy plasmid has led to the isolatio
n of a 4-kilobase pair DNA fragment from Streptomyces coelicolor conta
ining homologous sequence, Computer-assisted analysis of the DNA seque
nce revealed three putative open reading frames (ORFs), ORF1, ORF2, an
d ORF3, ORF2 extends beyond the sequenced DNA fragment, and its deduce
d product shares no similarities with any other known proteins in the
data bases, ORF3 is also truncated, and its 41-amino acid C-terminal p
roduct is identical 60 the S. coelicolor adenine phosphoribosyltransfe
rase. The 847-amino acid ORF1 protein, with a predicted molecular mass
of 94.2 kDa, strongly resembled the relA and spoT gene products from
Escherichia coli and the homologs from Vibrio sp, strain S14, Haemophi
lus influenzae, Streptococcus equisimilis H46A, and Mycoplasma genital
ium, Unlike these proteins, the ORF1 amino acid sequence analysis reve
aled the presence of a putative ATP/GTP-binding domain, A mutant was g
enerated by deleting most of the ORF1 gene that showed an actinorhodin
e-nonproducing phenotype, while undecylprodigiosin and the calcium-dep
endent antibiotic were unaffected, The mutant strain grew at a much lo
wer rate than the wild-type strain, and spore formation was delayed, W
hen the gene was propagated on a low copy number vector, not only was
actinorhodine production restored, but actinorhodine and undecylprodig
iosin production was enhanced in both the mutant and wild-type strains
and morphological differentiation returned to wild-type characteristi
cs. (p)ppGpp synthetase activity was not detected in purified ribosome
s from the ORF1-deleted mutant, while it was restored by complementati
on of this strain.