PDBsum entry 1r0c

Transferase

PDB id: 1r0c

Contents

Protein chains

310 a.a. *

153 a.a. *

Ligands

PO4 ×2

NCD ×2

Metals

_ZN ×2

Waters ×553

* Residue conservation analysis

References listed in PDB file

Key reference

Title

Products in the t-State of aspartate transcarbamylase: crystal structure of the phosphate and n-Carbamyl-L-Aspartate ligated enzyme.

Authors

J.Huang, W.N.Lipscomb.

Ref.

Biochemistry, 2004, 43, 6422-6426. [DOI no: 10.1021/bi0302144]

PubMed id

15157076

Abstract

The structure of aspartate transcarbamylase of Escherichia coli ligated to products (phosphate and N-carbamyl-l-aspartate) has been determined at 2.37 A resolution (R-factor = 0.23, R(free) = 0.27). Results might indicate a product release mode, rather than close analogues to the transition state like those found in our earlier studies of other ligands (N-phosphonacetyl-L-aspartate, carbamyl phosphate plus malonate, phosphonoacetamide plus malonate, or citrate plus phosphate). Ordered product release, first carbamylaspartate (CLA) and then phosphate, might be facilitated by a 4 A movement of phosphate from the substrate-analogue position to the product (phosphate) binding position, and by a somewhat similar release movement of the other product (CLA) relative to its analogue (citrate). This movement is consistent with earlier studies of binding of either pyrophosphate or phosphate alone [Honzatko, R. B., and Lipscomb, W. N. (1982) J. Mol. Biol. 160, 265-286].

Secondary reference #1

Title

Insights into the mechanisms of catalysis and heterotropic regulation of escherichia coli aspartate transcarbamoylase based upon a structure of the enzyme complexed with the bisubstrate analogue n-Phosphonacetyl-L-Aspartate at 2.1 a.

Authors

L.Jin, B.Stec, W.N.Lipscomb, E.R.Kantrowitz.

Ref.

Proteins, 1999, 37, 729-742. [DOI no: 10.1002/(SICI)1097-0134(19991201)37:4<729::AID-PROT21>3.3.CO;2-6]

PubMed id

10651286

Figure 1.
Figure 1. Schematic diagram of the PALA binding site in the C1 chain of aspartate transcarbamoylase. Shown are all of the residues that have hydrogen bonding interactions (dashed lines) with PALA. The only substantial difference between the C1 and C6 active sites is a reorientation of the side chain of Arg54.

Figure 6.
Figure 6. Stereo view of the C1 catalytic chain of aspartate transcarbamoylase with the tetrahedral intermediate modeled into the active site. Shown are all the side chains that make direct contact with the intermediate from the C1 chain as well as Ser80 and Lys84 from the adjacent catalytic chain. Hydrogen bonds are shown as dashed lines.

The above figures are reproduced from the cited reference with permission from John Wiley & Sons, Inc.

Secondary reference #2

Title

Structural consequences of effector binding to the t state of aspartate carbamoyltransferase: crystal structures of the unligated and ATP- And ctp-Complexed enzymes at 2.6-A resolution.

Authors

R.C.Stevens, J.E.Gouaux, W.N.Lipscomb.

Ref.

Biochemistry, 1990, 29, 7691-7701. [DOI no: 10.1021/bi00485a019]

PubMed id

2271528

Secondary reference #3

Title

A single mutation in the regulatory chain of escherichia coli aspartate transcarbamoylase results in an extreme t-State structure.

Authors

M.K.Williams, B.Stec, E.R.Kantrowitz.

Ref.

J Mol Biol, 1998, 281, 121-134. [DOI no: 10.1006/jmbi.1998.1923]

PubMed id

9680480

Figure 1.
Figure 1. Stereoview of the r6 CTP binding site as determined by [Kosman et al 1993] and drawn using Protein Data Bank file 1rah. The hydrogen bonds between the g-phosphate of CTP to the side-chains of Thr82 and Lys94 are shown.

Figure 6.
Figure 6. Comparison of the models for the wild-type r1 (thick lines) and the Thr82 -> Ala r6 (thin lines) chains showing the asymmetry in the quaternary structure between the allosteric domains.

The above figures are reproduced from the cited reference with permission from Elsevier