2026/05/27 by Isidro Álvarez‐Escribano, Manuel Brenes‐Álvarez, Jens Georg +2 · 1 voice
Biochemistry, Genetics and Molecular Biology · Agricultural and Biological Sciences · #Photosynthetic Processes and Mechanisms #Light effects on plants #Biocrusts and Microbial Ecology
paper · doi:10.1093/nar/gkag575
openalex publication_date 2026/05/27 · openalex created_date 2026/06/23 · openalex updated_date 2026/07/27
Transcriptional interference is rarely documented in bacteria. In cyanobacteria, phycobilisomes are the major light-harvesting antennae, and their degradation under non-optimal conditions follows a tightly regulated genetic program leading to the production of NblA, a widely conserved proteolytic adapter. NblA production is regulated at both the transcriptional and post-transcriptional levels. Here, we uncover an additional regulatory layer mediated by an antisense RNA conserved in heterocyst-forming cyanobacteria. In Nostoc sp. PCC 7120, transcription of the abundant antisense RNA (asnblA) limits nblA mRNA accumulation. A strain unable to transcribe asnblA produces an excess of NblA, ultimately so harmful that suppressor mutations of nblA expression accumulate rapidly, underscoring the essential role of asnblA. Rifampicin time-series experiments and the inability of asnblA to regulate nblA expression in trans support transcriptional interference as the primary regulatory mechanism of asnblA. Mathematical modeling of nblA expression, supported by biological data, shows that asnblA plays a pivotal role in preventing leaky nblA expression under non-inducing conditions. Our work highlights the importance of antisense RNA-mediated regulation, particularly transcriptional interference, in establishing thresholds that prevent spurious expression of genes encoding critical cellular functions.