PDBsum entry 2aso

Structural protein

PDB id: 2aso

Contents

Protein chain

361 a.a.

Ligands

ATP

SPX

Metals

_CA

Waters ×314

PDB id:

2aso

Name:

Structural protein

Title:

Structure of rabbit actin in complex with sphinxolide b

Structure:

Actin, alpha skeletal muscle. Chain: a. Synonym: alpha-actin-1

Source:

Oryctolagus cuniculus. Rabbit. Organism_taxid: 9986

Biol. unit:

Dimer (from PQS)

Resolution:

1.70Å R-factor: 0.175 R-free: 0.213

Authors:

J.S.Allingham,A.Zampella,M.V.D'Auria,I.Rayment

Key ref:

J.S.Allingham et al. (2005). Structures of microfilament destabilizing toxins bound to actin provide insight into toxin design and activity. Proc Natl Acad Sci U S A, 102, 14527-14532. PubMed id: 16192358 DOI: 10.1073/pnas.0502089102

Date:

23-Aug-05 Release date: 11-Oct-05

Protein chain

P68135  (ACTS_RABIT) -  Actin, alpha skeletal muscle from Oryctolagus cuniculus

Seq: 377 a.a.

Struc: 361 a.a.*

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

Enzyme reactions

• Enzyme class: E.C.3.6.4.- - ?????

DOI no: 10.1073/pnas.0502089102

Proc Natl Acad Sci U S A 102:14527-14532 (2005)

PubMed id: 16192358

Structures of microfilament destabilizing toxins bound to actin provide insight into toxin design and activity.

J.S.Allingham, A.Zampella, M.V.D'Auria, I.Rayment.

ABSTRACT

Marine macrolides that disrupt the actin cytoskeleton are promising candidates for cancer treatment. Here, we present the actin-bound x-ray crystal structures of reidispongiolide A and C and sphinxolide B, three marine macrolides found among a recently discovered family of cytotoxic compounds. Their structures allow unequivocal assignment of the absolute configuration for each compound. A comparison of their actin-binding site to macrolides found in the trisoxazole family, as well as the divalent macrolide, swinholide A, reveals the existence of a common binding surface for a defined segment of their macrocyclic ring. This surface is located on a hydrophobic patch adjacent to the cleft separating domains 1 and 3 at the barbed-end of actin. The large area surrounding this surface accommodates a wide variety of conformations and designs observed in the macrocyclic component of barbed-end-targeting macrolides. Conversely, the binding pocket for the macrolide tail, located within the cleft itself, shows very limited variation. Functional characterization of these macrolides by using in vitro actin filament severing and polymerization assays demonstrate the necessity of the N-methyl-vinylformamide moiety at the terminus of the macrolide tail for toxin potency. These analyses also show the importance of stable interactions between the macrocyclic ring and the hydrophobic patch on actin for modifying filament structure and how this stability can be compromised by subtle changes in macrolactone ring composition. By identifying the essential components of these complex natural products that underlie their high actin affinity, we have established a framework for designing new therapeutic agents.

Selected figure(s)

Figure 3.
Fig. 3. Overlay of RedA, SphB, and KabC on actin. (A) RedA (green sticks) and SphB (cyan sticks) are shown superimposed in their actin-bound conformation on a surface drawing of actin. Common actin residue contacts are shown in salmon. Residues contacting RedA but not SphB are shown in yellow. Selected atoms and the lactone ring of each toxin have been labeled for reference. (B) RedA (green sticks) and KabC (yellow sticks) are shown superimposed in their actin-bound conformation. Residues that are common to the binding of both RedA and KabC are colored salmon. KabC atom numbers are given primes ('). The coordinates for KabC actin were obtained from Protein Data Bank entry 1QZ5 [PDB] . Toxins were superimposed on actin by using the program SUPERPOSE in CCP4.

Figure 4.
Fig. 4. RedA and KabC contacts on actin. (A) Stereoview of the tail portions of RedA (green ball and stick) and KabC (yellow ball and stick) bound to actin. RedA actin is shown in orange. KabC actin is shown in blue. Contact residues are shown as sticks. The N-methyl-vinylformamide moieties of RedA and KabC are depicted with bridging water molecules from each complex. Waters from the RedA-actin complex are pink; waters from the KabC-actin complex are violet. (B) Stereoview of the ring portions of RedA and KabC. Coloring is as described in A.

Figures were selected by an automated process.