Roles of sodium hydrogen antiporter in secondary metabolites production and /or secretion by streptomyces coelicolor A3(2)

Abstract

Sodium/Hydrogen (Na+/H+) antiporters, briefly SHA’s, are ubiquitous membrane proteins that are involved in homeostasis of H+ and Na+ throughout the biological kingdom. Corroborating their roles in pH homeostasis, many of the SHA proteins are regulated directly by pH. The major objective of this study was to understand the roles of SHA’s in the production and/or secretion of secondary metabolites by S. coelicolor A3(2) M145. For this purpose, sha 7 gene (SCO7832) was deleted from S. coelicolor A3(2) chromosome since it was one of the two sha genes, together with sha 4, that showed the strongest gene dosage effect on actinorhodin and undecylprodigiosin production. The transformant of Δsha 7 was constructed by double-crossover between recombinant plasmid pKC1139-LRNeo and the S. coelicolor A3(2) chromosome. When the initial pH and NaCl concentration were changed in the ranges of 4 ~ 7 and 0 ~ 1 M, Δsha 7 showed lower production of actinorhodin and undecylprodigiosin than the wild strain in overall, as expected. No notable pH effects were observed, while a high NaCl concentration reduced their production in Δsha 7 more severely than in the wild strain. When an acidic pH shock was applied to Δsha 7, it was observed that the secondary metabolites production was significantly suppressed in overall.