UNLABELLED: ABCF-ATPases are increasingly recognized as translation factors that rescue stalled ribosomes when they encounter difficult mRNA templates or are stalled by antibiotics. The latter defines antibiotic resistance ABCF (ARE ABCF) proteins, known for their role in antibiotic resistance. However, in this study, we reveal a broader role of ARE ABCFs in antibiotic-responsive regulation. Using genetic, OMICs, and biochemical approaches, we showed that ARE ABCF proteins TiaA and Are5sc in Streptomyces coelicolor use their resistance functions to modulate specialized metabolism and proteosynthesis in response to lincosamide, streptogramin A, and pleuromutilin (LSAP) antibiotics. Although under LSAP exposure, either Are5sc or TiaA is essential for activating the biosynthesis of the redox-active antimicrobial actinorhodin, these proteins exhibit distinct functions at the proteome level, defined by their resistance profiles and temporally regulated expression. Are5sc facilitates early adaptive responses by modulating the WblC regulon across a broad range of LSAP concentrations, while TiaA is induced later, specifically at higher concentrations, where it suppresses antibiotic stress responses, particularly against pleuromutilins. TiaA function thus reflects the ecological context of LSAP antibiotics as pleuromutilins are produced by fungi, whereas lincosamides/streptogramins originate from actinomycetes. Our findings demonstrate that ARE ABCF proteins, through their resistance function, act as global regulators of translation, mirroring the roles of non-ARE ABCF proteins like EttA. This highlights their broader ecological and physiological significance, extending beyond their established role in antibiotic resistance. IMPORTANCE: Bacteria adapt to diverse stimuli mainly through transcriptional changes that regulate adaptive protein factors. Here, we show that responses to protein synthesis-inhibiting antibiotics are fine-tuned by antibiotic resistance ABCF proteins at the translational level, enabling bacteria to differentiate between antibiotic classes and concentrations for a tailored response. Additionally, we have demonstrated that these proteins can specialize in conferring high-level resistance to specific antibiotics. Given their prevalence in pathogenic bacteria, antibiotic resistance ABCF (ARE ABCF) proteins may play a crucial role in resistance development, particularly against new antibiotics targeting the ribosomal catalytic center, presenting a significant challenge for antimicrobial therapy.

• Keywords
• ABCF proteins, Streptomyces, antibiotic resistance, stress adaptation, stress response, translational control,
• MeSH
• Anti-Bacterial Agents * pharmacology   MeSH
• Drug Resistance, Bacterial * MeSH
• Bacterial Proteins * genetics   metabolism   MeSH
• Diterpenes pharmacology   MeSH
• Lincosamides pharmacology   MeSH
• Microbial Sensitivity Tests MeSH
• Pleuromutilins MeSH
• Polycyclic Compounds pharmacology   MeSH
• Protein Biosynthesis MeSH
• Gene Expression Regulation, Bacterial drug effects   MeSH
• Streptomyces coelicolor * drug effects   genetics   metabolism   MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Anti-Bacterial Agents * MeSH
• Bacterial Proteins * MeSH
• Diterpenes MeSH
• Lincosamides MeSH
• Pleuromutilins MeSH
• Polycyclic Compounds MeSH

In natural environments, antibiotics are important means of interspecies competition. At subinhibitory concentrations, they act as cues or signals inducing antibiotic production; however, our knowledge of well-documented antibiotic-based sensing systems is limited. Here, for the soil actinobacterium Streptomyces lincolnensis, we describe a fundamentally new ribosome-mediated signaling cascade that accelerates the onset of lincomycin production in response to an external ribosome-targeting antibiotic to synchronize antibiotic production within the population. The entire cascade is encoded in the lincomycin biosynthetic gene cluster (BGC) and consists of three lincomycin resistance proteins in addition to the transcriptional regulator LmbU: a lincomycin transporter (LmrA), a 23S rRNA methyltransferase (LmrB), both of which confer high resistance, and an ATP-binding cassette family F (ABCF) ATPase, LmrC, which confers only moderate resistance but is essential for antibiotic-induced signal transduction. Specifically, antibiotic sensing occurs via ribosome-mediated attenuation, which activates LmrC production in response to lincosamide, streptogramin A, or pleuromutilin antibiotics. Then, ATPase activity of the ribosome-associated LmrC triggers the transcription of lmbU and consequently the expression of lincomycin BGC. Finally, the production of LmrC is downregulated by LmrA and LmrB, which reduces the amount of ribosome-bound antibiotic and thus fine-tunes the cascade. We propose that analogous ABCF-mediated signaling systems are relatively common because many ribosome-targeting antibiotic BGCs encode an ABCF protein accompanied by additional resistance protein(s) and transcriptional regulators. Moreover, we revealed that three of the eight coproduced ABCF proteins of S. lincolnensis are clindamycin responsive, suggesting that the ABCF-mediated antibiotic signaling may be a widely utilized tool for chemical communication. IMPORTANCE Resistance proteins are perceived as mechanisms protecting bacteria from the inhibitory effect of their produced antibiotics or antibiotics from competitors. Here, we report that antibiotic resistance proteins regulate lincomycin biosynthesis in response to subinhibitory concentrations of antibiotics. In particular, we show the dual character of the ABCF ATPase LmrC, which confers antibiotic resistance and simultaneously transduces a signal from ribosome-bound antibiotics to gene expression, where the 5' untranslated sequence upstream of its encoding gene functions as a primary antibiotic sensor. ABCF-mediated antibiotic signaling can in principle function not only in the induction of antibiotic biosynthesis but also in selective gene expression in response to any small molecules targeting the 50S ribosomal subunit, including clinically important antibiotics, to mediate intercellular antibiotic signaling and stress response induction. Moreover, the resistance-regulatory function of LmrC presented here for the first time unifies functionally inconsistent ABCF family members involving antibiotic resistance proteins and translational regulators.

• Keywords
• ABCF ATPase, Streptomyces, antibiotic biosynthesis, antibiotic resistance, antibiotic-mediated signaling, chemical communication, regulation of gene expression, ribosomal regulation, signal transduction, specialized metabolism,
• MeSH
• Adenosine Triphosphatases metabolism   MeSH
• Anti-Bacterial Agents biosynthesis   pharmacology   MeSH
• Drug Resistance, Bacterial MeSH
• Bacterial Proteins genetics   metabolism   MeSH
• Lincomycin biosynthesis   pharmacology   MeSH
• Methyltransferases MeSH
• Multigene Family MeSH
• Multidrug Resistance-Associated Proteins genetics   metabolism   MeSH
• Gene Expression Regulation, Bacterial drug effects   MeSH
• Ribosomes metabolism   MeSH
• Signal Transduction MeSH
• Streptomyces metabolism   MeSH
• Transcription Factors MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Adenosine Triphosphatases MeSH
• Anti-Bacterial Agents MeSH
• Bacterial Proteins MeSH
• Lincomycin MeSH
• Methyltransferases MeSH
• Multidrug Resistance-Associated Proteins MeSH
• rRNA (adenosine-O-2'-)methyltransferase MeSH Browser
• Transcription Factors MeSH