Metabolic pathways and regulatory networks associated to NAI-107 lantibiotic production in Microbispora sp. ATCC-PTA-5024

Abstract

The filamentous actinobacterium Microbispora sp. ATCC-PTA-5024 produces the lantibiotic NAI-107, which is effective against multidrugresistant Gram-positive pathogens. In actinomycetes, the biosynthesis of antibiotics is elicited as a physiological response that is controlled by a complex regulatory network involving general and pathwayspecific regulators. The ‘omics technologies can be useful to explore molecular physiology in bacterial cells and elucidate molecular and metabolic events associated to antibiotic production in order to develop robust and economically-feasible production processes. To this aim, differential proteomic analyses, based two-dimensional difference in gel electrophoresis (2D-DIGE) and mass spectrometry (MS) approaches, combined with differential fluorescence microscopy (DFM) and molecular genetic studies were carried out on M. sp. ATCC-PTA-5024. M. sp. ATCC-PTA-5024 fermentations, showing a first biomass accumulation (A) stage followed by a of biomass yield decline (D) stage, revealed that NAI-107 yield starts at mid A stage and increases up to mid D stage. 2D-DIGE and MS analyses were carried out at A and D stages to reveal patterns of differentially regulated proteins associated to on set and maintenance of NAI-107 production, respectively. Regulatory and metabolic proteins were identified and possible role in physiological differentiation of an unknown regulatory protein was investigated by the construction of an over-expressing strain. Impact of NAI-107 on cell physiology and metabolism was analysed using a non-producing mutant confirming possible role of identified proteins in self-resistance mechanism. Molecular aspect of activation of specific stress response mechanism were confirmed by DFM. These results originally elucidate regulatory networks, biochemical pathways and molecular processes occurring during growth and lantibiotic production, thus providing the first functional picture of a member of the Microbispora genus.