1vjr

Protein Summary

The gene TM1742 from Thermotoga maritima encodes a 4-nitrophenylphosphatase EC:3.1.3.41.  The enzyme was previously crystallized 1PW5.  According to the fold type, the enzyme belongs to the family of NagD-like phosphohydrolase, a superfamily of haloalkanoic acid dehalogenases (HAD) PF00702 SCOP56783.  The enzyme catalyzes the hydrolysis of 4-nitrophenyl phosphate to form  4-nitrophenol.

Putative Function: Uracil Monophophatase (UMPase)

Not a pNPPase:

When compared to E. coli(K-12 Strain) nagD protein (PDB 2C4N), TM1742 (PDB 1VJR) shares high structural and sequence similarity. The 3 important structural domains (Motif I, Motif II and the Cap Domain) are all conserved between both proteins, leading to the hypothesis that TM1742 is more correctly a nagD protein instead of a pNPPase protein. A NagD protein splits a ribonucleoside monophosphate into its respective ribonucleoside and a phosphate through the nucleophilic attack of phosphorus by water. Specifically, the Cap Domain may inhibit any enzymatic activity in relation to pNPP but promote enzymatic activity relating to ribonucleotide monophosphate (RMP) substrates, more specifically uridine monophosphate (UMP). This specificity should occur due to the hypothesized interaction between the Cap Domain and the aromatic moiety of the UMP molecule.

When compared with E. coli class B acid phosphatase (PDB 2B82), TM1742 also shares a high degree of structural and sequence similarity. However, the Cap Domain is not conserved in the acid phosphatase protein, despite this protein showing specificity for adenosine monophosphate (AMP). Upon further examination of the interactions between the acid phosphatase active site and an AMP molecule, it is apparent that a non-conserved Cap Domain is used (F56 & Y193). This leads to the further hypothesis that the presence of a Cap Domain, in some capacity, allows for specificity of RMPs to occur in these types of phosphatase proteins. Thus, pNPP would not be able to undergo conversion to pNP in TM1742 due to a lack of the hypothesized interaction with the Cap Domain.

BioLEd Contributors: Joseph Breheny, Kanishk Jain, Ryan Oliver, Justin Kim, Damian Njoku, Andaleeb Rahman, Tyler Skinner, Tsiga Solomon, Alison Underwood, Kristen Waterfield, Cameron Mura, Carol Price, Linda Columbus. Funded by NSF DUE 1044858.

Ligand Summary

References