PDBsum entry: 1im0

Hydrolase, membrane protein

PDB id: 1im0

Contents

Protein chain

262 a.a. *

Ligands

BOG ×4

MPD ×3

Waters ×19

* Residue conservation analysis

PDB id:

1im0

Name:

Hydrolase, membrane protein

Title:

Outer membrane phospholipase a from escherichia coli n156a active site mutant ph 8.3

Structure:

Outer membrane phsopholipase a. Chain: a. Synonym: ompla, detergent-resistant phospholipase a, dr- phospholipase a, phosphatidylcholine 1-acylhydrolase. Engineered: yes. Mutation: yes

Source:

Escherichia coli. Organism_taxid: 562. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

2.98Å R-factor: 0.226 R-free: 0.266

Authors:

H.J.Snijder,J.H.Van Eerde,R.L.Kingma,K.H.Kalk,N.Dekker, M.R.Egmond,B.W.Dijkstra

Key ref:

H.J.Snijder et al. (2001). Structural investigations of the active-site mutant Asn156Ala of outer membrane phospholipase A: function of the Asn-His interaction in the catalytic triad. Protein Sci, 10, 1962-1969. PubMed id: 11567087 DOI: 10.1110/ps.17701

Date:

09-May-01 Release date: 03-Oct-01

Protein chain

P0A921  (PA1_ECOLI) -  Phospholipase A1

Seq: 289 a.a.

Struc: 262 a.a.*

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

Enzyme reactions

• Enzyme class 1: E.C.3.1.1.32 - Phospholipase A(1).
• Reaction: Phosphatidylcholine + H₂O = 2-acylglycerophosphocholine + a carboxylate
• Cofactor: Calcium
• Enzyme class 2: E.C.3.1.1.4 - Phospholipase A(2).
• Reaction: Phosphatidylcholine + H₂O = 1-acylglycerophosphocholine + a carboxylate
• Cofactor: Calcium

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 

• Cellular component: membrane (5 terms)
• Biological process: lipid metabolic process (2 terms)
• Biochemical function: hydrolase activity (9 terms)

reference

DOI no: 10.1110/ps.17701

Protein Sci 10:1962-1969 (2001)

PubMed id: 11567087

Structural investigations of the active-site mutant Asn156Ala of outer membrane phospholipase A: function of the Asn-His interaction in the catalytic triad.

H.J.Snijder, J.H.Van Eerde, R.L.Kingma, K.H.Kalk, N.Dekker, M.R.Egmond, B.W.Dijkstra.

ABSTRACT

Outer membrane phospholipase A (OMPLA) from Escherichia coli is an integral-membrane enzyme with a unique His-Ser-Asn catalytic triad. In serine proteases and serine esterases usually an Asp occurs in the catalytic triad; its role has been the subject of much debate. Here the role of the uncharged asparagine in the active site of OMPLA is investigated by structural characterization of the Asn156Ala mutant. Asparagine 156 is not involved in maintaining the overall active-site configuration and does not contribute significantly to the thermal stability of OMPLA. The active-site histidine retains an active conformation in the mutant notwithstanding the loss of the hydrogen bond to the asparagine side chain. Instead, stabilization of the correct tautomeric form of the histidine can account for the observed decrease in activity of the Asn156Ala mutant.