Structural highlights
Disease
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.[1] 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.[2]
Function
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 essential for normal lung surfactant function, which is in itself essential to life. However, the molecular basis for SP-B's activity is not understood and a high-resolution structure for SP-B has not been determined. Mini-B is a 34-residue peptide with internal disulfide linkages that is composed of the N- and C-terminal helical regions of SP-B. It has been shown to retain similar activity to full-length SP-B in certain in vitro and in vivo studies. We have used solution NMR to determine the structure of Mini-B in the presence of micelles composed of the anionic detergent sodium dodecyl sulfate (SDS). Under these conditions, Mini-B forms two alpha-helices connected by an unstructured loop. Mini-B possesses a strikingly amphipathic surface with a large positively charged patch on one face of the peptide and a large hydrophobic patch on the opposite face. A tryptophan side chain extends outward from the peptide in a position to interact with lipids at the polar/apolar interface. Interhelix interactions are stabilized by both disulfide bonds and by interleaving of hydrophobic side chains from the two helices.
Structure of mini-B, a functional fragment of surfactant protein B, in detergent micelles.,Sarker M, Waring AJ, Walther FJ, Keough KM, Booth V Biochemistry. 2007 Oct 2;46(39):11047-56. Epub 2007 Sep 11. PMID:17845058[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Ballard PL, Nogee LM, Beers MF, Ballard RA, Planer BC, Polk L, deMello DE, Moxley MA, Longmore WJ. Partial deficiency of surfactant protein B in an infant with chronic lung disease. Pediatrics. 1995 Dec;96(6):1046-52. PMID:7491219
- ↑ Haataja R, Ramet M, Marttila R, Hallman M. Surfactant proteins A and B as interactive genetic determinants of neonatal respiratory distress syndrome. Hum Mol Genet. 2000 Nov 1;9(18):2751-60. PMID:11063734
- ↑ Sarker M, Waring AJ, Walther FJ, Keough KM, Booth V. Structure of mini-B, a functional fragment of surfactant protein B, in detergent micelles. Biochemistry. 2007 Oct 2;46(39):11047-56. Epub 2007 Sep 11. PMID:17845058 doi:http://dx.doi.org/10.1021/bi7011756
