Catalyzes the removal of elemental sulfur and selenium atoms from L-cysteine, L-cystine, L-selenocysteine, and L-selenocystine to produce L-alanine (PubMed:12033984, PubMed:16455656). Supplies the inorganic sulfur for iron-sulfur (Fe-S) clusters (PubMed:15480755, PubMed:17372218). Required for the maturation of all plastidic Fe-S proteins and, thus, essential for plant growth (PubMed:17372218). [sulfur carrier]-H + L-cysteine = [sulfur carrier]-SH + L-alanine AH2 + L-selenocysteine = A + H(+) + hydrogenselenide + L-alanine The cysteine desulfurase activity is stimulated over 40-fold upon complex formation with SUFE1 (PubMed:16437155, PubMed:16455656). Optimum pH is 7-9. Heterotetramer with SUFE1 (PubMed:16455656). Interacts with QS (PubMed:18978034). Interacts with SUFE1 (PubMed:16437155, PubMed:18978034). Ubiquitous. NFS2-overexpressing transgenic plants have enhanced ability to tolerate and accumulate Se and may be used in phytoremediation. Belongs to the class-V pyridoxal-phosphate-dependent aminotransferase family.