RAMC Production by Developmentally Impaired Mutants of Streptomyces coelicolor

Abstract

The RamC protein is required for the production of spore-forming cells called aerial hyphae in colonies of 𝘚𝘵𝘳𝘦𝘱𝘵𝘰𝘮𝘺𝘤𝘦𝘴 𝘤𝘰𝘦𝘭𝘪𝘤𝘰𝘭𝘰𝘳. RamC can be detected during the period between 24 and 48 hours following spore germination however there is a dramatic drop in RamC levels thereafter. This could be explained either by the existence of an active means of RamC removal or by the fact that at later time points in the 𝘚. 𝘤𝘰𝘦𝘭𝘪𝘤𝘰𝘭𝘰𝘳 lifecycle non-RamC producing cells vastly outnumber RamC-producing cells. characterized a large number of 𝘣𝘭𝘥 mutants and found that most of them do not produce RamC. In the majority of the 𝘣𝘭𝘥 mutants that do produce RamC, we observed the same pattern of accumulation and loss during colony growth as in wildtype colonies. Furthermore, we identified a small number of mutants that produced RamC such that it persisted at detectable levels for a longer duration or only appeared after a substantial delay relative to the wildtype. None of these RamC-producing 𝘣𝘭𝘥 mutants was complemented by plasmids containing a cloned 𝘣𝘭𝘥𝘔, 𝘣𝘭𝘥𝘕 or 𝘳𝘢𝘮𝘙 gene, mutations in which also cause persistent or delayed RamC production. These results suggest either that there is more than one differentiated cell type within the substrate mycelium or that 𝘚. 𝘤𝘰𝘦𝘭𝘪𝘤𝘰𝘭𝘰𝘳 colonies actively rid themselves of RamC once the protein's biological function has passed.