PDBsum entry 1w5r

Transferase

PDB id: 1w5r

Contents

Protein chains

273 a.a. *

Waters ×398

* Residue conservation analysis

PDB id:

1w5r

Name:

Transferase

Title:

X-ray crystallographic structure of a c70q mycobacterium smegmatis n- arylamine acetyltransferase

Structure:

Arylamine n-acetyltransferase. Chain: a, b. Engineered: yes. Mutation: yes

Source:

Mycobacterium smegmatis. Organism_taxid: 1772. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

1.45Å R-factor: 0.197 R-free: 0.220

Authors:

S.J.Holton,J.Sandy,F.Rodrigues-Lima,J.-M.Dupret,S.Bhakta,M.E.M.Noble, E.Sim

Key ref:

J.Sandy et al. (2005). Investigation of the catalytic triad of arylamine N-acetyltransferases: essential residues required for acetyl transfer to arylamines. Biochem J, 390, 115-123. PubMed id: 15869465

Date:

09-Aug-04 Release date: 11-May-05

Protein chains

O86309  (NAT_MYCSM) -  Arylamine N-acetyltransferase from Mycolicibacterium smegmatis

Seq: 275 a.a.

Struc: 273 a.a.*

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

Enzyme reactions

• Enzyme class: E.C.2.3.1.5 - arylamine N-acetyltransferase.
• Reaction: an arylamine + acetyl-CoA = an N-acetylarylamine + CoA

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

reference

Biochem J 390:115-123 (2005)

PubMed id: 15869465

Investigation of the catalytic triad of arylamine N-acetyltransferases: essential residues required for acetyl transfer to arylamines.

J.Sandy, A.Mushtaq, S.J.Holton, P.Schartau, M.E.Noble, E.Sim.

ABSTRACT

The NATs (arylamine N-acetyltransferases) are a well documented family of enzymes found in both prokaryotes and eukaryotes. NATs are responsible for the acetylation of a range of arylamine, arylhydrazine and hydrazine compounds. We present here an investigation into the catalytic triad of residues (Cys-His-Asp) and other structural features of NATs using a variety of methods, including site-directed mutagenesis, X-ray crystallography and bioinformatics analysis, in order to investigate whether each of the residues of the catalytic triad is essential for catalytic activity. The catalytic triad of residues, Cys-His-Asp, is a well defined motif present in several families of enzymes. We mutated each of the catalytic residues in turn to investigate the role they play in catalysis. We also mutated a key residue, Gly126, implicated in acetyl-CoA binding, to examine the effects on acetylation activity. In addition, we have solved the structure of a C70Q mutant of Mycobacterium smegmatis NAT to a resolution of 1.45 A (where 1 A=0.1 nm). This structure confirms that the mutated protein is correctly folded, and provides a structural model for an acetylated NAT intermediate. Our bioinformatics investigation analysed the extent of sequence conservation between all eukaryotic and prokaryotic NAT enzymes for which sequence data are available. This revealed several new sequences, not yet reported, of NAT paralogues. Together, these studies have provided insight into the fundamental core of NAT enzymes, and the regions where sequence differences account for the functional diversity of this family. We have confirmed that each of the three residues of the triad is essential for acetylation activity.