A widespread Actinobacterial G Protein System regulates production of specialized metabolites in Streptomyces coelicolor
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Actinobacterial G protein systems (AGPSs), also known as conservons, are regulatory systems that are broadly distributed within Actinomycetota. AGPSs are composed of a minimum of four proteins, including a sensor histidine kinase, a small Ras-like GTPase, a roadblock/MglB protein (likely a GTPase activating protein), and protein with a domain of unknown function that likely functions as a guanine-nucleotide exchange factor (GEF). While progress has been made in understanding AGPS function at the mechanistic level, the phylogenetic distribution of individual AGPSs, and the genes and processes they regulate, remain largely unmapped. Previously, the Cvn8 AGPS of Streptomyces coelicolor was found to influence expression of genes in multiple specialized metabolic pathways during interspecies interactions with other actinomycetes. However, the impact of the Cvn8 AGPS on specialized metabolism has not been assessed at the chemical level. Here, we investigated the phylogenetic distribution of the Cvn8 AGPS clade,and assessed the impact of the Cvn8 AGPS on natural product biosynthesis using untargeted metabolomics. In a set of 485 actinobacterial genomes, we found that members of the clade that includes the Cvn8 AGPS from S. coelicolor are widely distributed in the lineages known to produce specialized metabolites. We also found that in S. coelicolor , the pattern of specialized metabolite production varied in mutants lacking specific components of the Cvn8 AGPS. Specifically, normal production of the pigmented antibiotic actinorhodin during interspecies interactions required cvnA8 and cvnF8 , while a ΔcvnD8 overproduced undecylprodigiosin. Together, these results connect a widespread AGPS to control of specialized metabolism in a model actinomycete.
Importance
Actinobacterial G protein systems (AGPSs) are found widely in bacteria in the phylum Actinomycetota, including genera like Streptomyces that produce many useful molecules and pathogens such as Mycobacterium tuberculosis . The genes and functions regulated by these regulatory systems are largely unknown. Here we investigated the role of the Cvn8 AGPS in controlling the production of specialized metabolites, like antibiotics, in the model actinomycete Streptomyces coelicolor . We found that specific components of the Cvn8 AGPS were required for normal production of the antibiotic actinorhodin during interactions between S. coelicolor and another actinomycete. We also show that Cvn8 belongs to a group of AGPSs that is found broadly in the genus Streptomyces and in more distantly related orders of Actinomycetota such as the Pseudonorcardiales and Micromonosporales. Together, these results raise the possibility that this group of AGPSs may influence specialized metabolism across a broad range of Actinomycetota lineages.
