PDBsum entry 2gex

Oxidoreductase

PDB id: 2gex

Contents

Protein chains

146 a.a. *

133 a.a. *

Waters ×31

* Residue conservation analysis

PDB id:

2gex

Name:

Oxidoreductase

Title:

Crystal structure of snoal2 a putative hydroxylase from streptomyces nogalater

Structure:

Snol. Chain: a, b. Synonym: snoal2, putative hydroxylase. Engineered: yes

Source:

Streptomyces nogalater. Organism_taxid: 38314. Gene: snoal2. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Resolution:

2.50Å R-factor: 0.219 R-free: 0.249

Authors:

P.Beinker,B.Lohkamp,G.Schneider

Key ref:

P.Beinker et al. (2006). Crystal structures of SnoaL2 and AclR: two putative hydroxylases in the biosynthesis of aromatic polyketide antibiotics. J Mol Biol, 359, 728-740. PubMed id: 16650858 DOI: 10.1016/j.jmb.2006.03.060

Date:

21-Mar-06 Release date: 18-Jul-06

Protein chain

Q9RN64  (Q9RN64_STRNO) -  SnoL from Streptomyces nogalater

Seq: 139 a.a.

Struc: 146 a.a.

Protein chain

Q9RN64  (Q9RN64_STRNO) -  SnoL from Streptomyces nogalater

Seq: 139 a.a.

Struc: 133 a.a.

DOI no: 10.1016/j.jmb.2006.03.060

J Mol Biol 359:728-740 (2006)

PubMed id: 16650858

Crystal structures of SnoaL2 and AclR: two putative hydroxylases in the biosynthesis of aromatic polyketide antibiotics.

P.Beinker, B.Lohkamp, T.Peltonen, J.Niemi, P.Mäntsälä, G.Schneider.

ABSTRACT

SnoaL2 and AclR are homologous enzymes in the biosynthesis of the aromatic polyketides nogalamycin in Streptomyces nogalater and cinerubin in Streptomyces galilaeus, respectively. Evidence obtained from gene transfer experiments suggested that SnoaL2 catalyzes the hydroxylation of the C-1 carbon atom of the polyketide chain. Here we show that AclR is also involved in the production of 1-hydroxylated anthracyclines in vivo. The three-dimensional structure of SnoaL2 has been determined by multi-wavelength anomalous diffraction to 2.5A resolution, and that of AclR to 1.8A resolution using molecular replacement. Both enzymes are dimers in solution and in the crystal. The fold of the enzyme subunits consists of an alpha+beta barrel. The dimer interface is formed by packing of the beta-sheets from the two subunits against each other. In the interior of the alpha+beta barrel a hydrophobic cavity is formed that most likely binds the substrate and harbors the active site. The subunit fold and the architecture of the active site in SnoaL2 and AclR are similar to that of the polyketide cyclases SnoaL and AknH; however, they show completely different quaternary structures. A comparison of the active site pockets of the putative hydroxylases AclR and SnoaL2 with those of bona fide polyketide cyclases reveals distinct differences in amino acids lining the cavity that might be responsible for the switch in chemistry. The moderate degree of sequence similarity and the preservation of the three-dimensional fold of the polypeptide chain suggest that these enzymes are evolutionary related. Members of this enzyme family appear to have evolved from a common protein scaffold by divergent evolution to catalyze reactions chemically as diverse as aldol condensation and hydroxylation.

Selected figure(s)

Figure 3.
Figure 3. Structure of SnoaL2. (a) Structure of the SnoaL2 dimer. The secondary structure elements in subunit A are colored differently, helices cyan and b-strands magenta. The part of helix H5 in subunit A that is from the C-terminal linker/tag peptide is shown in dark blue. The secondary structural elements and the termini are labeled. Subunit B of the dimer is shown in green. (b) Superposition of the two chains of SnoaL2. Chain A is shown in cyan (the C-terminal linker/tag helix is colored dark blue) and chain B in magenta. The orientation of the monomers is the same as for chain A in (a). C[A] and C[B] indicate the C termini of chain A and B, respectively. (c) Experimental MAD electron density after solvent flattening and the final model for the C termini of chain A and B, respectively. The chains are colored as in (b) and the corresponding maps are shown in blue for chain A and red for chain B. The maps are contoured at 1.5s. The models and maps are superimposed according to the NCS.

Figure 4.
Figure 4. Structure of AclR. Superposition of the dimers of SnoaL2 (cyan) and AclR (magenta). Subunits B are shown in darker colors. The upper right helix of AclR is only observed in subunit A, and corresponds to the C-terminal linker peptide and the hexahistidine tag (colored in yellow).

The above figures are reprinted by permission from Elsevier: J Mol Biol (2006, 359, 728-740) copyright 2006.

Figures were selected by an automated process.