PDBsum entry: 1o8n

Molybdenum cofactor biosynthesis

PDB-id: 1o8n

Biological unit = asymmetric unit,
as shown
(as defined in PDB file)

Contents

Description

Header details

Header records

References

PROCHECK

Protein chains

163 a.a. *

Waters ×49

* Residue conservation analysis

Tools

Clefts Calculation

PDB id:

1o8n

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 462-628. Synonym: molybdenum cofactor, biosynthesis enzyme cnx1. Engineered: yes. Mutation: yes

Source:

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

Biological unit:

Trimer (from PDB file)

UniProt:

Chains A, B, C: Q39054 (CNX1_ARATH)

Seq:

Struc:

Seq:

Struc:

Seq:

670 a.a.

Struc:

163 a.a.*

Key:	PfamA domain
Secondary structure	CATH domain

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

Resolution:

2.8Å

R-factor:

0.196

R-free:

0.231

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:

27-Feb-03

Related entries:

1eav crystal structures of human gephyrin and plant cnx1 g domains - comparative analysis and functional implications
1o8o the active site of the molybdenum cofactor biosenthetic protein domain cnx1g
1o8q the active site of the molybdenum cofactor biosenthetic protein domain cnx1g

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Surface

Key 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.