ABSTRACT
The nucleotide sequence of a two-component signal transduction operon (cutRS) of Streptomyces lividans TK64 was elucidated. Transcription of the operon was detected during the transition and stationary phases of growth, initiating at a single site upstream of cutR. This promoter region also possessed promoter activity directed away from cutRS, which appears to be responsible for the previously observed suppression of the translational deficiency of a melC1 mutation. Mutations in cutR and cutS were generated by gene replacement. The resulting mutants exhibited accelerated and increased production of the polyketide antibiotic, actinorhodin, which could be reversed by introduction of cutR on a plasmid. cutRS was also shown to repress actinorhodin production in the closely related species, Streptomyces coelicolor A3(2). The cutRS operon is the second two-component system found in Streptomyces that negatively regulates secondary metabolism.
Subject(s)
Anti-Bacterial Agents/metabolism , Bacterial Proteins/genetics , Gene Expression Regulation, Bacterial , Streptomyces/genetics , Transcription Factors , Transferases , Amino Acid Sequence , Anthraquinones/metabolism , Bacterial Proteins/metabolism , Base Sequence , Molecular Sequence Data , Mutagenesis, Site-Directed , Mutation , Operon , Phenotype , Sequence Analysis, DNA , Sequence Homology, Amino Acid , Signal Transduction , Time Factors , Transcription, GeneticABSTRACT
Dust concentrations in ice of the last glacial maximum (LGM) are high in ice cores from Greenland and Antarctica. The magnitude of the enhancements can be explained if the strength of the hydrologic cycle during the LGM was about half of that at present. This notion is consistent with a large decrease (5 degrees Celsius) in ocean temperature during the LGM, as recently deduced from measurements of strontium and calcium in corals.
