The anticodon stem of initiator tRNA (i‐tRNA) possesses the characteristic three consecutive GC base pairs (G29:C41, G30:C40, and G31:C39 abbreviated as GC/GC/GC or 3GC pairs) crucial to commencing translation. To understand the importance of this highly conserved element, we isolated two fast‐growing suppressors of Escherichia coli sustained solely on an unconventional i‐tRNA (i‐tRNAcg/GC/cg) having cg/GC/cg sequence instead of the conventional GC/GC/GC. Both suppressors have the common mutation of V93A in initiation factor 3 (IF3), and additional mutations of either V32L (Sup‐1) or H76L (Sup‐2) in small subunit ribosomal protein 12 (uS12). The V93A mutation in IF3 was necessary for relaxed fidelity of i‐tRNA selection to sustain on i‐tRNAcg/GC/cg though with a retarded growth. Subsequent mutations in uS12 salvaged the retarded growth by enhancing the fidelity of translation. The H76L mutation in uS12 showed better fidelity of i‐tRNA selection. However, the V32L mutation compensated for the deficient fidelity of i‐tRNA selection by ensuring an efficient fidelity check by ribosome recycling factor (RRF). We reveal unique genetic networks between uS12, IF3 and i‐tRNA in initiation and between uS12, elongation factor‐G (EF‐G), RRF, and Pth (peptidyl‐tRNA hydrolase) which, taken together, govern the fidelity of translation in bacteria.

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Spatially compound extremes pose substantial threats to globally interconnected social-economic systems. We use an Earth system model large ensemble to examine the future risk of compound droughts during the boreal summer over ten global regions with highly seasonal climate. Relative to the late-20th century, the probability, mean extent and severity of compound droughts increase by ~60%, ~10% and ~20% respectively by the late-21st century, with a disproportionate increase in risk across North America and the Amazon. These changes result in a ~9-fold increase in exposure over agricultural areas and ~5 to 20-fold increase in population exposure depending on the shared socioeconomic pathway. ENSO is the predominant large-scale driver of compound droughts with 68% of historical events occurring during El Niño or La Niña conditions. ENSO teleconnections remain stationary in the future though an ~22% increase in ENSO extremes combined with projected warming, drive the elevated risk of compound droughts.