Overview A groundbreaking study published on November 18, 2025 , by researchers from the Bose Institute , an autonomous institute of the Department of Science and Technology (DST) , and Rutgers University , has overturned a central textbook model of bacterial gene regulation. This new understanding unveils new paths for understanding bacterial gene regulation and its evolution, potentially aiding in the design of better antibiotics or regulatory inhibitors that block infection mechanisms. Key Findings The study challenges the 50-year-old “σ (sigma) cycle” model of bacterial gene regulation. Researchers found that the principal transcription initiation factor in Bacillus subtilis — σA —remains bound to RNA polymerase throughout transcription. This contrasts with the previously held belief based on observations of E. coli σ70 , where the sigma factor dissociates after initiation. Detailed Analysis The Sigma Cycle For nearly 50 years , biology has understood bacterial gene regulation through the “σ (sigma) cycle.” This model posits that sigma factors bind RNA polymerase to initiate transcription and then dissociate to allow elongation. This concept was primarily based on observations of the bacterial strain E. coli σ70 . New Research The new study reveals that this cycle is not a universal phenomenon. Researchers from the Bose Institute and Rutgers University have demonstrated that in Bacillus subtilis , the σA factor remains attached to RNA polymerase throughout the transcription process. Dr. Jayanta Mukhopadhyay , corresponding author from the Bose Institute , stated, “Our work shows that in Bacillus subtilis , the σA factor stays attached to RNA polymerase all the way through the transcription process. This fundamentally changes how we think about bacterial transcription and gene regulation.” Methodology The researchers used a combination of modern techniques, including: Biochemical assays Chromatin immunoprecipitation Fluorescence-based imaging These techniques allowed them to observe the sigma factor’s behavior in real time. They found that Bacillus subtilis σA and an E. coli σ70 variant lacking a part called 1.1 remain stably associated with transcription complexes. This is in stark contrast to full-length E. coli σ70 , which is released stochastically during elongation. Implications Aniruddha Tewari of Bose Institute added, “These findings provide compelling evidence that the long-accepted σ cycle does not apply to all bacteria. It opens new avenues for understanding bacterial gene regulation and its evolution.” The discovery has broad implications for microbiology, potentially influencing how researchers approach bacterial physiology, stress response, and the development of antibiotics targeting transcription. By controlling gene regulation, scientists can design microorganisms that produce biofuels, biodegradable plastics, or therapeutic compounds efficiently. UPSC Relevance This discovery is relevant to the UPSC Civil Services Exam , particularly under GS Paper III (Science and Technology) . It highlights advancements in biotechnology and their potential applications in medicine and industry. Key Contributors Besides Dr. Tewary and Dr. Mukhopadhyay , contributors include: Shreya Sengupta Soumya Mukherjee Nilanjana Hazra (from Bose Institute, Kolkata) Yon W. Ebright Richard H. Ebright (from Rutgers University, USA) Publication Details The study was published in the Proceedings of the National Academy of Sciences (PNAS) . Publication link: doi:10.1073/pnas. 2503801122