TatD DNase Domain Containing Protein 3 (TATDN3)

TATDN3 Belongs to the tatD DNase family. ThetatD gene product has two homologues in E. colicoded by the unlinked ycfH and yjjV genes. AnE. coli strain with in-frame chromosomal deletions in all three of tatD, ycfH, and yjjVexhibits no significant defect in the cellular location of five cofactor-containing enzymes that are synthesized with twin arginine signal peptides. Neither these mutations nor overproduction of the TatD protein cause any discernible effect on the export kinetics of an additional E. coli Tat pathway substrate. It is concluded that proteins of the TatD family have no obligate involvement in protein export by the Tat system. TatD is shown to be a cytoplasmic protein. TatD binds to immobilized Ni2+ or Zn2+affinity columns and exhibits magnesium-dependent DNase activity. Features of the tatA operon that may control TatD expression are discussed.