PDBsum entry: 1o8o

Molybdenum cofactor biosynthesis

PDB id: 1o8o

Contents

Protein chains

162 a.a. *

Waters ×64

* Residue conservation analysis

PDB id:

1o8o

Name:

Molybdenum cofactor biosynthesis

Title:

The active site of the molybdenum cofactor biosynthetic protein domain cnx1g

Structure:

Molybdopterin biosynthesis cnx1 protein. Chain: a, b, c. Fragment: cnx1 g-domain, residues 462-623. Engineered: yes. Mutation: yes

Source:

Arabidopsis thaliana. Mouse-ear cress. Organism_taxid: 3702. Strain: cv. Columbia. Expressed in: escherichia coli. Expression_system_taxid: 562.

Biol. unit:

Trimer (from PDB file)

Resolution:

2.7Å R-factor: 0.200 R-free: 0.243

Authors:

J.Kuper,J.Winking,H.J.Hecht,G.Schwarz,R.R.Mendel

Key ref:

J.Kuper et al. (2003). The active site of the molybdenum cofactor biosynthetic protein domain Cnx1G. Arch Biochem Biophys, 411, 36-46. PubMed id: 12590921 DOI: 10.1016/S0003-9861(02)00714-2

Date:

28-Nov-02 Release date: 04-Dec-03

Protein chains

Q39054  (CNX1_ARATH) -  Molybdopterin biosynthesis protein CNX1

Seq: 670 a.a.

Struc: 162 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class 2: E.C.2.10.1.1 - Molybdopterin molybdotransferase.
• Reaction: Adenylyl-molybdopterin + molybdate = molybdenum cofactor + AMP
• Cofactor: Zinc or magnesium
• Enzyme class 3: E.C.2.7.7.75 - Molybdopterin adenylyltransferase.
• Reaction: ATP + molybdopterin = diphosphate + adenylyl-molybdopterin
• Cofactor: Manganese or magnesium

Note, where more than one E.C. class is given (as above), each may correspond to a different protein domain or, in the case of polyprotein precursors, to a different mature protein.

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

 Gene Ontology (GO) functional annotation 

• Biological process: Mo-molybdopterin cofactor biosynthetic process (1 term)

reference

DOI no: 10.1016/S0003-9861(02)00714-2

Arch Biochem Biophys 411:36-46 (2003)

PubMed id: 12590921

The active site of the molybdenum cofactor biosynthetic protein domain Cnx1G.

J.Kuper, J.Winking, H.J.Hecht, R.R.Mendel, G.Schwarz.

ABSTRACT

The final step of molybdenum cofactor biosynthesis in plants is catalyzed by the two-domain protein Cnx1. The G domain of Cnx1 (Cnx1G) binds molybdopterin with high affinity and transfers molybdenum to molybdopterin. Here, we describe the functional and structural characterization of structure-based Cnx1G mutants. For molybdopterin binding residues Thr542 and Ser573 were found to be important because different mutations of those residues resulted in 7- to 26-fold higher k(D) values for molybdopterin binding. Furthermore, we showed that the terminal phosphate of molybdopterin is directly involved in protein-pterin interactions as dephosphorylated molybdopterin binds with one magnitude of order lower affinity to the wild-type protein. Molybdopterin binding was not affected in mutants defective in Ser476, Asp486, or Asp515. However, molybdenum insertion was completely abolished, indicating their important role for catalysis. Based on these results we propose the binding of molybdopterin to a large depression in the structure of Cnx1G formed by beta5, alpha5, beta6, and alpha6, whereas the negatively charged depression formed by the loop between beta3 and alpha4, the N-terminal end of alpha2, the 3(10) helix, and the region between beta6 and alpha6 is involved in catalysis.