Unique crystal structure of a novel surfactant protein from the foam nest of the frog Leptodactylus vastus.
Breeding by releasing eggs into stable biofoams ("foam nests") is a peculiar reproduction mode within anurans, fish, and tunicates; not much is known regarding the biochemistry or molecular mechanisms involved. Lv-ranaspumin (Lv-RSN-1) is the predominant protein from the foam nest of the frog Leptodactylus vastus. This protein shows natural surfactant activity, which is assumed to be crucial for stabilizing foam nests. We elucidated the amino acid sequence of Lv-RSN-1 by de novo sequencing with mass-spectrometry and determined the high-resolution X-ray structure of the protein. It has a unique fold mainly composed of a bundle of 11 α-helices and two small antiparallel β-strands. Lv-RSN-1 has a surface rich in hydrophilic residues and a lipophilic cavity in the region of the antiparallel β-sheet. It possesses intrinsic surface-active properties, reducing the surface tension of water from 73 to 61 mN m(-1) (15 μg mL(-1)). Lv-RSN-1 belongs to a new class of surfactants proteins for which little has been reported regarding structure or function.
Lab. de Ecologia Microbiana e Biotecnologia-LEMBiotech, Departamento de Biologia, Universidade Federal do Ceará, Av. Humberto Monte 2977, Campus do Pici, Bloco 909, Fortaleza, CE, 60455-000 (Brazil).
Denise
D
Cavalcante Hissa
Gustavo
G
Arruda Bezerra
Ruth
R
Birner-Gruenberger
Luciano
L
Paulino Silva
Isabel
I
Usón
Karl
K
Gruber
Vânia Maria
VM
Maciel Melo
D000818:Animals; D001001:Anura / Q000378:metabolism*; D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D030562:Databases, Protein; D057927:Hydrophobic and Hydrophilic Interactions; D013058:Mass Spectrometry; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism; D020539:Sequence Analysis, Protein; D013500:Surface Tension
D011506:Proteins
Lv-ranaspumin; amphibians; mass spectrometry; structural biology; surfactants