Regulation of the AbrA1/A2 Two-Component System in Streptomyces coelicolor and the Potential of Its Deletion Strain as a Heterologous Host for Antibiotic Production

Abstract

The Two-Component System (TCS) AbrA1/A2 from Streptomyces coelicolor M145 is a negative regulator of antibiotic production and morphological differentiation. In this work we show that it is able to auto-regulate its expression, exerting a positive induction of its own operon promoter, and that its activation is dependent on the presence of iron. The overexpression of the abrA2 response regulator (RR) gene in the mutant ΔabrA1/A2 results in a toxic phenotype. The reason is an excess of phosphorylated AbrA2, as shown by phosphoablative and phosphomimetic AbrA2 mutants. Therefore, non-cognate histidine kinases (HKs) or small phospho-donors may be responsible for AbrA2 phosphorylation in vivo. The results suggest that in the parent strain S. coelicolor M145 the correct amount of phosphorylated AbrA2 is adjusted through the phosphorylation-dephosphorylation activity rate of the HK AbrA1. Furthermore, the ABC transporter system, which is part of the four-gene operon comprising AbrA1/A2, is necessary to de-repress antibiotic production in the TCS null mutant. Finally, in order to test the possible biotechnological applications of the ΔabrA1/A2 strain, we demonstrate that the production of the antitumoral antibiotic oviedomycin is duplicated in this strain as compared with the production obtained in the wild type, showing that this strain is a good host for heterologous antibiotic production. Thus, this genetically modified strain could be interesting for the biotechnology industry.

Regulation of antibiotic production in Actinobacteria: new perspectives from the post-genomic era

“…coelicolor is that iron de6represses the pleiotropic TCS, AbrA1/A2, which negatively regulates Act and Red production, although the mechanism has not yet been resolved 237 .…”

Streptomycetes: Surrogate hosts for the genetic manipulation of biosynthetic gene clusters and production of natural products

“…Yepes et al identified arbA1/A2 encoding a pleiotropic repressor of antibiotic production in S. coelicolor (Yepes et al, 2011). The deletion of arbA1/A2 in M145 (ΔabrA) not only enhanced the production of endogenous antibiotics such as ACT, RED and CDA, but also foreign NPs; the expression of the entire oviedomycin pathway derived from S. antibiotics ATCC 11891 in the ΔabrA mutant duplicated oviedomycin production as compared to the parent host M145 (Rico et al, 2014). Interestingly, expression of a pSET152 construct containing only 12 structural genes controlled by a single hrdB promoter in S. coelicolor M1146 also produced oviedomycin (Xu et al, 2017b).…”

Toward a new focus in antibiotic and drug discovery from the Streptomyces arsenal

“…Nevertheless, the signals that activate the different Streptomyces' TCS remain mostly unknown and just a few of them have been described to date (Figure 1D ). As an example, in S. coelicolor phosphate is the signal triggering PhoP/R (Sola-Landa et al, 2003 ), nitrogen balance seems to be related with AfsQ (Shu et al, 2009 ) and DraR/K (Yu et al, 2012 ) regulation, the level of iron seems to be the signal activating AbrA1/2 activator (Rico et al, 2014 ) and the presence of heme-oxidative stress provokes SenS/R reaction (Bogel et al, 2007 ; Ortiz de Orue Lucana and Groves, 2009 ). Most of the signals sensed by the TCS present in the genome of the Streptomyces spp.…”