A hypothetical protein TT1808 (also known as Uma2 or TTHA1514), a putative restriction endonuclease (IPR008538), is an AT-rich DNA binding protein from Thermus thermophilus. The domain exhibits a 3-layer α/β/α topology that is comparable to that of restriction endonucleases. Enzymes involved in nucleic acid metabolism, particularly nucleases serving a variety of biological functions, frequently exhibit nuclease domains.