The superoxide dismutase
(SOD) identified as interacting with SSG-1 belongs to a family of enzymes that catalyze the dismutation of oxygen radical to hydrogen peroxide eliminating superoxide anions generated in aerobic respiration [47, 48]. Many SOD genes have been identified in fungal genomes . SODs have been shown to contribute to growth and survival of fungi under oxidative stress conditions, specifically inside macrophages. In C. neoformans, SOD1 mutants were observed to be less virulent while SOD2 mutants had increased susceptibility to oxidative stress and showed decreased growth at elevated temperatures [50, 51]. Virulence in C. neoformans variety gattii has been reported to be dependent on both SOD1 and SOD2 [32, 33]. In C. albicans the null mutant of mitochondrial SOD2 was more sensitive than wild-type cells to stress  Fedratinib and the SOD1 null mutant had attenuated virulence . S. schenckii superoxide dismutases have not been studied. In fact, this is the first report of the presence of a member of this protein family in this fungus. Analysis of the amino acid sequence of SsSOD against the Homo
sapiens database using BLAST shows that it is homologous to the human manganese superoxide dismutase SOD2 family with 32% identity. This same analysis, using the fungal databases revealed that SsSOD is phylogenetically selleck compound closely related to SODs of the filamentous fungi with the sequence identity being in the range of 23-43%.
Also SsSOD has a calculated molecular Vorinostat weight of 35.44 kDa, very close to that of other fungal homologues. The specific role of SOD2 in S. schenckii stress and pathogenesis has yet to be addressed. Fungal SODs have two main locations: cytosolic or mitochondrial . Analysis using PSORT II  and TargetP  suggests that SsSOD isolated by the yeast two-hybrid analysis is a mitochondrial SOD. Being a mitochondrial protein does not disqualify SsSOD as an interacting partner of SSG-1. It is important to note that Gαi subunits can be present not only in the cytoplasm but also in the mitochondria . Also, SODs acquire the metal ion during protein synthesis and this seems to occur in the cytoplasmic face of the mitochondrial membrane. It is also of interest Resminostat to note that another mitochondrial protein was also found to interact with SSG-1 (unpublished results). This protein belongs of the mitochondrial metal transporter protein family (Mtm family) that is known to be involved in the acquisition of the metal ion by SODs [55, 56]. These results together with the interactions of SSG-1 and the metal ion transporters SsNramp and SsSit, discussed below suggest a possible role of SSG-1 in SODs metal acquisition. Metals are essential nutrients and important co-factors of a variety of proteins and enzymes; they are required for the survival of all organisms. Fungi have developed multiple strategies to acquire metals from the environment .