5'-deoxy-5'-methylthioadenosine phosphorylases (MTAP) similar to Sulfolobus solfataricus MTAPII and Pseudomonas aeruginosa PAO1 5'-methylthioinosine phosphorylase (MTIP)
MTAP catalyzes the reversible phosphorolysis of 5'-deoxy-5'-methylthioadenosine (MTA) to adenine and 5-methylthio-D-ribose-1-phosphate. This subfamily includes human MTAP which is highly specific for MTA, and Sulfolobus solfataricus MTAPII which accepts adenosine in addition to MTA. Two MTAPs have been isolated from S. solfataricus: SsMTAP1 and SsMTAPII, SsMTAP1 belongs to a different subfamily of the nucleoside phosphorylase-I (NP-I) family. This group also includes Pseudomonas aeruginosa PAO1 MTI phosphorylase (MTIP) which uses 5'-methylthioinosine (MTI) as a preferred substrate, and does not use MTA. NP-I family members accept a range of purine nucleosides as well as the pyrimidine nucleoside uridine. The NP-1 family includes phosphorolytic nucleosidases, such as purine nucleoside phosphorylase (PNPs, EC. 2.4.2.1), uridine phosphorylase (UP, EC 2.4.2.3), and 5'-deoxy-5'-methylthioadenosine phosphorylase (MTAP, EC 2.4.2.28), and hydrolytic nucleosidases, such as AMP nucleosidase (AMN, EC 3.2.2.4), and 5'-methylthioadenosine/S-adenosylhomocysteine (MTA/SAH) nucleosidase (MTAN, EC 3.2.2.16). The NP-I family is distinct from nucleoside phosphorylase-II, which belongs to a different structural family.
Structure:2A8Y: Sulfolobus solfataricus MTAP homohexamer bound with 5'-deoxy- 5'methylthioadenosine and sulfate in each of 6 active sites; contacts at 4A - View structure with Cn3D
Jiyao W et al.(2023). "The conserved domain database in 2023.",