PDBsum entry 3e28

Lyase

PDB id: 3e28

Contents

Protein chains

215 a.a. *

204 a.a. *

Ligands

SO4 ×16

Metals

_ZN ×6

Waters ×172

* Residue conservation analysis

PDB id:

3e28

Name:

Lyase

Title:

H. Influenzae beta-carbonic anhydrase, variant y181f

Structure:

Carbonic anhydrase 2. Chain: a, b, c, d, e, f. Synonym: carbonate dehydratase 2. Engineered: yes. Mutation: yes

Source:

Haemophilus influenzae. Organism_taxid: 727. Gene: can, hi1301. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.50Å R-factor: 0.208 R-free: 0.256

Authors:

R.S.Rowlett,J.Lee

Key ref:

R.S.Rowlett et al. (2009). Allosteric site variants of Haemophilus influenzae beta-carbonic anhydrase. Biochemistry, 48, 6146-6156. PubMed id: 19459702

Date:

05-Aug-08 Release date: 02-Jun-09

Protein chains

P45148  (CAN_HAEIN) -  Carbonic anhydrase 2 from Haemophilus influenzae (strain ATCC 51907 / DSM 11121 / KW20 / Rd)

Seq: 229 a.a.

Struc: 215 a.a.*

Protein chains

P45148  (CAN_HAEIN) -  Carbonic anhydrase 2 from Haemophilus influenzae (strain ATCC 51907 / DSM 11121 / KW20 / Rd)

Seq: 229 a.a.

Struc: 204 a.a.*

* PDB and UniProt seqs differ at 2 residue positions (black crosses)

Enzyme reactions

• Enzyme class: Chains A, B, C, D, E, F: E.C.4.2.1.1 - carbonic anhydrase.
• Reaction: hydrogencarbonate + H⁺ = CO2 + H2O
• Cofactor: Zn(2+)

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

Added reference

Biochemistry 48:6146-6156 (2009)

PubMed id: 19459702

Allosteric site variants of Haemophilus influenzae beta-carbonic anhydrase.

R.S.Rowlett, C.Tu, J.Lee, A.G.Herman, D.A.Chapnick, S.H.Shah, P.C.Gareiss.

ABSTRACT

Haemophilus influenzae beta-carbonic anhydrase (HICA) is hypothesized to be an allosteric protein that is regulated by the binding of bicarbonate ion to a non-catalytic (inhibitory) site that controls the ligation of Asp44 to the catalytically essential zinc ion. We report here the X-ray crystallographic structures of two variants (W39F and Y181F) involved in the binding of bicarbonate ion in the non-catalytic site and an active-site variant (D44N) that is incapable of forming a strong zinc ligand. The alteration of Trp39 to Phe increases the apparent K(i) for bicarbonate inhibition by 4.8-fold. While the structures of W39F and Y181F are very similar to the wild-type enzyme, the X-ray crystal structure of the D44N variant reveals that it has adopted an active-site conformation nearly identical to that of non-allosteric beta-carbonic anhydrases. We propose that the structure of the D44N variant is likely to be representative of the active conformation of the enzyme. These results lend additional support to the hypothesis that HICA is an allosteric enzyme that can adopt active and inactive conformations, the latter of which is stabilized by bicarbonate ion binding to a non-catalytic site.