THE SMALL PROTEIN TRPM MODULATES MORPHO-PHYSIOLOGICAL DIFFERENTIATION IN THE MODEL ACTINOMYCETE STREPTOMYCES COELICOLOR A3(2)

BACKGROUNDS TrpM, a small protein of 63 amino acids, modulates tryptophan (Trp) metabolism and morpho-physiological differentiation in the filamentous bacterium Streptomyces coelicolor A3(2), a model organism for antibiotic production and cell differentiation. Indeed, the trpM knock-out mutant strain is characterized by a delayed growth on minimal medium, smaller aerial hyphae, and reduction of both spore and antibiotic actinorhodin production in comparison with the wild-type strain. These observations were in agreement with proteomic analyses which highlighted a role for TrpM in controlling i) Trp production through Trp precursor availability and, thus ii) bacterial growth and morpho-physiological differentiation. OBJECTIVES Construction and morpho-physiological characterization of a S. coelicolor A3(2) trpM knock-in mutant. METHODS - Construction of a trpM knock-in mutant by E. coli-S. coelicolor interspecific conjugation using the pIJ8600/trpM integrative plasmid. - Scanning Electron Microscope (SEM) analysis. - Spectrophotometric analysis and microbiological assays for evaluating antibiotic production. CONCLUSIONS A trpM knock-in mutant strain of S. celicolor A3(2) was constructed and showed an increased production of actinorhodin and spores: moreover, SEM analysis revealed an earlier formation of septa in aerial hyphae and confirmed that TrpM has a role in controlling the morpho-physiological differentiation of S. coelicolor A3(2).