[1S05e] 13. Microbial Engineering for Natural Products Synthesis - Part 3

5:15 PM - 5:30 PM JST(8:15 AM - 8:30 AM UTC)

[1MENP-15] Dual-calibration RT-qPCR reveals distinct dnaK1/2/3 and groES-groEL1/2 expression dynamics underlying stress-enhanced sinefungin production in Streptomyces incarnatus

○Takashi Tamura¹ (1. Okayama University (Japan))

Keywords:

Nucleoside Antibiotics,Heat Shock Proteins,cis-acting element,Stress-Induced Production Enhancement,HrcA-CIRCE system

Streptomyces incarnatus NRRL8089 produces sinefungin, a nucleoside antibiotic with broad antimicrobial activity. Defined environmental stresses enhance production: heat shock (44 °C for 24 h) doubles titres, whereas acidification to pH 4 increases titres nearly threefold despite reduced growth. Dual-calibration RT-qPCR quantifies moderate induction (<10-fold) of the dnaK1-dnaJ1 and groES-groEL1 operons and upregulation of monocistronic homologues dnaK2, dnaK3 and groEL2 by up to 125-fold. Promoter alignments and mFold predictions indicate that conserved inverted repeats and promoter secondary-structure stability act as cis-acting "gain-control" elements that tune paralogue inducibility. Structural modelling suggests divergence among DnaK paralogues in the substrate-binding lid, consistent with stress-dependent repartitioning of client handling, whereas GroEL1 and GroEL2 share a conserved scaffold with substitutions largely outside the cavity, pointing to kinetic specialisation. Collectively, these findings link stress-responsive proteostasis to enhance sinefungin biosynthesis in actinomycetes.