Disruption of sblA in Streptomyces lividans permits expression of a heterologous α-amylase gene in the presence of glucose The EMBL accession number for the sequence reported in this paper is AJ223365.

Abstract

In a transposition mutant of Streptomyces lividans TK24, the usually glucoserepressible expression of a heterologous α-amylase gene (aml) became resistant to glucose repression. The transposon had inserted into an ORF called sblA which encodes a 274 aa product sharing significant sequence similarities with various phosphatases that act on small phosphorylated substrates. sblA was transcribed as a monocistronic mRNA and its transcription was enhanced at the transition phase. Because its transcriptional and putative translational start points coincide, sblA is likely to be translated in the absence of a conventional RBS. The sblA-disrupted mutant is characterized by early growth arrest in glucose-grown cultures and by partial relief of glucose repression of aml expression.

Phosphoinositides Are Involved in Control of the Glucose-Dependent Growth Resumption That Follows the Transition Phase inStreptomyces lividans

“…Furthermore, the sblA mutant strain was shown to enter prematurely into stationary phase when grown in a minimal medium containing glucose as a main carbon source. In contrast, very little or no difference in the growth profile of the wild-type and mutant strains was observed when cells were grown in the presence of glycerol (14). In order to get a better understanding of the role of sblA in the phenomenon of glucose repression, we assessed the growth characteristics and glucose uptake abilities of the wild-type and the sblA mutant strains of S. lividans TK24 grown in the complex liquid or solid medium R2YE, rich or poor in glucose.…”

“…The early growth arrest that characterizes the sblA mutant strain was previously established in a liquid minimal medium containing glucose as main carbon source (14). To further explore the phenotype of the sblA mutant, we grew cultures of S. lividans TK24 and TK24 sblA::⍀aac in the more complex and rich R2YE liquid medium with or without added glucose.…”

“…The Streptomyces strains used were the wild-type strain S. lividans TK24 (19), the S. lividans TK24 sblA::⍀aac strain (14) and the S. lividans TK24 EcoRI::⍀aac sblA (this study) strain derived from it as well as S. lividans TK24 carrying the replicative vector pHC1002 or the integrative vectors pHC1013, pHC1023, pHC1053, pHC1063, and pHC1073 ( Fig. 1).…”

“…In this mutant, the gene sblA (equivalent to SCO0479 of S. coelicolor) was interrupted. This gene was predicted to encode a protein of 274 amino acids bearing some similarities to phosphatases of the inositol phosphate monophosphatase family (14). Furthermore, the sblA mutant strain was shown to enter prematurely into stationary phase when grown in a minimal medium containing glucose as a main carbon source.…”

“…Our scientific interest for this subject led us to isolate mutants of Streptomyces lividans TK24 resistant to glucose catabolite repression by using transposon mutagenesis. We isolated and characterized a mutant that showed the expected relief of glucose repression of the expression of a normally strongly glucose-repressed alphaamylase gene (14). In this mutant, the gene sblA (equivalent to SCO0479 of S. coelicolor) was interrupted.…”