Solution NMR Structure of Surfactant Protein B (11-25) (SP-B11-25)
[PSPB_HUMAN] Defects in SFTPB are the cause of pulmonary surfactant metabolism dysfunction type 1 (SMDP1) [MIM:265120]; also called pulmonary alveolar proteinosis due to surfactant protein B deficiency. A rare lung disorder due to impaired surfactant homeostasis. It is characterized by alveolar filling with floccular material that stains positive using the periodic acid-Schiff method and is derived from surfactant phospholipids and protein components. Excessive lipoproteins accumulation in the alveoli results in severe respiratory distress. Genetic variations in SFTPB are a cause of susceptibility to respiratory distress syndrome in premature infants (RDS) [MIM:267450]. RDS is a lung disease affecting usually premature newborn infants. It is characterized by deficient gas exchange, diffuse atelectasis, high-permeability lung edema and fibrin-rich alveolar deposits called 'hyaline membranes'. Note=A variation Ile to Thr at position 131 influences the association between specific alleles of SFTPA1 and respiratory distress syndrome in premature infants.
[PSPB_HUMAN] Pulmonary surfactant-associated proteins promote alveolar stability by lowering the surface tension at the air-liquid interface in the peripheral air spaces. SP-B increases the collapse pressure of palmitic acid to nearly 70 millinewtons per meter.
Publication Abstract from PubMed
Surfactant protein B (SP-B) is a 79-residue essential component of lung surfactant, the film of lipid and protein lining the alveoli, and is the subject of great interest for its role in lung surfactant replacement therapies. Here we report circular dichroism results and the solution NMR structure of SP-B(11-25) (CRALIKRIQAMIPKG) dissolved in CD(3)OH at 5 degrees C. This is the first report of NMR data related to the protein SP-B, whose structure promises to help elucidate the mechanism of its function. Sequence-specific resonance assignments were made for all observable (1)H NMR signals on the basis of standard 2D NMR methods. Structures were determined by the simulated annealing method using restraints derived from 2D NOESY data. The calculations yielded 17 energy-minimized structures, three of which were subjected to 0.95 ns of restrained dynamics to assess the relevance of the static structures to more realistic dynamic behavior. Our CD and NMR data confirm that this segment is an amphiphilic alpha helix from approximately residue L14 through M21. The backbone heavy-atom RMSD for residues L14 through M21 is 0.09 +/- 0.12 A, and the backbone heavy-atom RMSD for the whole peptide is 0.96 +/- 2.45 A, the difference reflecting fraying at the termini. Aside from the disordered termini, the minimized structures represent dynamic structures well. Structural similarity to the homologous regions of related saposin-like proteins and the importance of the distribution of polar residues about the helix axis are discussed.
NMR structure of lung surfactant peptide SP-B(11-25).,Kurutz JW, Lee KY Biochemistry. 2002 Jul 30;41(30):9627-36. PMID:12135384
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.