PDBsum entry 2wgo

Surfactant protein

PDB id: 2wgo

Contents

Protein chain

98 a.a.

PDB id:

2wgo

Name:

Surfactant protein

Title:

Structure of ranaspumin-2, a surfactant protein from the foam nests of a tropical frog

Structure:

Ranaspumin-2. Chain: a. Fragment: residues 2-97. Synonym: rsn-2. Engineered: yes. Other_details: ranaspumin-2 with an amphiphilic amino acid sequence, exhibits substantial detergent-like surfactant activity necessary for production of foam, yet is harmless to the membranes of eggs and spermatozoa

Source:

Engystomops pustulosus. Tungara frog. Organism_taxid: 76066. Organ: oviduct. Expressed in: escherichia coli. Expression_system_taxid: 469008.

NMR struc:

25 models

Authors:

C.D.Mackenzie,B.O.Smith,M.W.Kennedy,A.Cooper

Key ref:

C.D.Mackenzie et al. (2009). Ranaspumin-2: structure and function of a surfactant protein from the foam nests of a tropical frog. Biophys J, 96, 4984-4992. PubMed id: 19527658

Date:

21-Apr-09 Release date: 23-Jun-09

Protein chain

B5DCK2  (B5DCK2_ENGPU) -  Ranaspumin-2 from Engystomops pustulosus

Seq: 97 a.a.

Struc: 98 a.a.*

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

Biophys J 96:4984-4992 (2009)

PubMed id: 19527658

Ranaspumin-2: structure and function of a surfactant protein from the foam nests of a tropical frog.

C.D.Mackenzie, B.O.Smith, A.Meister, A.Blume, X.Zhao, J.R.Lu, M.W.Kennedy, A.Cooper.

ABSTRACT

Ranaspumin-2 (Rsn-2) is a monomeric, 11 kDa surfactant protein identified as one of the major foam nest components of the túngara frog (Engystomops pustulosus), with an amino acid sequence unlike any other protein described so far. We report here on its structure in solution as determined by high-resolution NMR analysis, together with investigations of its conformation and packing at the air-water interface using a combination of infrared and neutron reflectivity techniques. Despite the lack of any significant sequence similarity, Rsn-2 in solution adopts a compact globular fold characteristic of the cystatin family, comprising a single helix over a four-stranded sheet, in a motif not previously associated with surfactant activity. The NMR structure of Rsn-2 shows no obvious amphiphilicity that might be anticipated for a surfactant protein. This suggests that it must undergo a significant conformational change when incorporated into the air-water interface that may involve a hinge-bending, clamshell opening of the separate helix and sheet segments to expose hydrophobic faces to air while maintaining the highly polar surfaces in contact with the underlying water layer. This model is supported by direct observation of the relative orientations of secondary structure elements at the interface by infrared reflection absorption spectroscopy, and by protein packing densities determined from neutron reflectivity profiles.