The DUF59 Containing Protein SufT Is Involved in the Maturation of Iron-Sulfur (FeS) Proteins during Conditions of High FeS Cofactor Demand in Staphylococcus aureus

摘要

Proteins containing DUF59 domains have roles in iron-sulfur (FeS) cluster assembly and are widespread throughout Eukarya, Bacteria, and Archaea. However, the function(s) of this domain is unknown. Staphylococcus aureus SufT is composed solely of a DUF59 domain. We noted that sufT is often co-localized with sufBC , which encode for the Suf FeS cluster biosynthetic machinery. Phylogenetic analyses indicated that sufT was recruited to the suf operon, suggesting a role for SufT in FeS cluster assembly. A S . aureus Δ sufT mutant was defective in the assembly of FeS proteins. The DUF59 protein Rv1466 from Mycobacterium tuberculosis partially corrected the phenotypes of a Δ sufT mutant, consistent with a widespread role for DUF59 in FeS protein maturation. SufT was dispensable for FeS protein maturation during conditions that imposed a low cellular demand for FeS cluster assembly. In contrast, the role of SufT was maximal during conditions imposing a high demand for FeS cluster assembly. SufT was not involved in the repair of FeS clusters damaged by reactive oxygen species or in the physical protection of FeS clusters from oxidants. Nfu is a FeS cluster carrier and nfu displayed synergy with sufT . Furthermore, introduction of nfu upon a multicopy plasmid partially corrected the phenotypes of the Δ sufT mutant. Biofilm formation and exoprotein production are critical for S . aureus pathogenesis and vancomycin is a drug of last-resort to treat staphylococcal infections. Defective FeS protein maturation resulted in increased biofilm formation, decreased production of exoproteins, increased resistance to vancomycin, and the appearance of phenotypes consistent with vancomycin-intermediate resistant S . aureus . We propose that SufT, and by extension the DUF59 domain, is an accessory factor that functions in the maturation of FeS proteins. In S . aureus , the involvement of SufT is maximal during conditions of high demand for FeS proteins. Author Summary Iron-sulfur (FeS) clusters are inorganic cofactors that are used for diverse cellular processes including cellular respiration, DNA replication and repair, antibiotic resistance, and dinitrogen fixation. A failure to properly assemble FeS clusters in proteins results in widespread metabolic disorders, metabolic paralysis, and oftentimes cell death. Therefore, the biosynthesis of FeS clusters is essential for nearly all organisms. Proteins containing DUF59 domains are widespread in Eukarya, Bacteria, and Archaea. Proteins containing DUF59 domains have roles in FeS cluster assembly, but the function(s) of the DUF59 domain is unknown. Moreover, the function(s) of proteins containing DUF59 domains are largely unknown. Staphylococcus aureus SufT is composed solely of a DUF59 domain, which provides a unique opportunity to examine the role(s) of this domain in cellular physiology. In this report we show SufT to be an accessory factor utilized in FeS cluster assembly during conditions imposing a high-demand for FeS proteins. We also show that deficiencies in the maturation of FeS proteins result in alterations in the ability of S . aureus , an epidemic human pathogen, to form biofilms, produce exoproteins, and resist antibiotic stress.