Cargo protein of a type 2A encapsulin nanocompartment involved in sulfur metabolism. Cysteine desulfurases mobilize the sulfur from L-cysteine to yield L-alanine, an essential step in sulfur metabolism for biosynthesis of a variety of sulfur-containing biomolecules. [sulfur carrier]-H + L-cysteine = [sulfur carrier]-SH + L-alanine There are 1-2 copies of this protein in each type 2A encapsulin shell. Belongs to the class-V pyridoxal-phosphate-dependent aminotransferase family. Csd subfamily. Truncated N-terminus.