Coordinated adaptation of to calprotectin-dependent metal sequestration.

Unlabelled: The host protein calprotectin inhibits the growth of a variety of bacterial pathogens through metal sequestration in a process known as "nutritional immunity." growth is inhibited by calprotectin , and calprotectin is localized to staphylococcal abscesses during infection. However, the staphylococcal adaptations that provide defense against nutritional immunity and the role of metal-responsive regulators are not fully characterized. In this work, we define the transcriptional response of and the role of the metal-responsive regulators, Zur, Fur, and MntR, in response to metal limitation by calprotectin exposure. Additionally, we identified genes affecting the fitness of during metal limitation through a Transposon sequencing (Tn-seq) approach. Loss of function mutations in , which encodes a proteolytic subunit of the ATP-dependent Clp protease, demonstrate reduced fitness of to the presence of calprotectin. ClpP contributes to pathogenesis in a calprotectin-dependent manner. These studies establish a critical role for ClpP to combat metal limitation by calprotectin and reveal the genes required for to outcompete the host for metals.

Importance: is a leading cause of skin and soft tissue infections, bloodstream infections, and endocarditis. Antibiotic treatment failures during infections are increasingly prevalent, highlighting the need for novel antimicrobial agents. Metal chelator-based therapeutics have tremendous potential as antimicrobials due to the strict requirement for nutrient metals exhibited by bacterial pathogens. The high-affinity transition metal-binding properties of calprotectin represents a potential therapeutic strategy that functions through metal chelation. Our studies provide a foundation to define mechanisms by which combats nutritional immunity and may be useful for the development of novel therapeutics to counter the ability of to survive in a metal-limited environment.