Copper and iron engage distinct metabolic programs for cellular survival

Copper and iron are redox-active micronutrients with tightly coupled homeostasis, yet how copper modulates iron-dependent stress responses remains unclear. Using Saccharomyces cerevisiae under nutrient-limited conditions, we uncoupled proliferative growth from long-term survival to dissect metal-dependent adaptation. Copper selectively preserved survival without affecting growth, whereas iron showed similar effects. Iron chelation impaired growth and suppressed electron transport chain gene expression; copper partially rescued these defects but required iron availability for its pro-survival activity. Despite this interdependence, copper and iron engaged distinct signaling programs. Iron-dependent survival required a Target of Rapamycin complex 1 (TORC1)-permissive state and was attenuated by rapamycin, whereas copper remained active under TORC1 inhibition. In contrast, copper promoted survival through AMP-activated protein kinase (AMPK) and antioxidant pathways, while iron exhibited context-dependent AMPK reliance. Together, these findings reveal that copper and iron support cellular survival through distinct metabolic programs and suggest that the consequences of micronutrient availability are shaped by the underlying nutrient-sensing and metabolic state of the cell. This framework provides insight into how alterations in micronutrient homeostasis and metabolic signaling may influence cellular resilience during aging.