An amphipathic helical motif common to tumourolytic polypeptide NK‐lysin and pulmonary surfactant polypeptide SP‐B

FEBS Letters

Curstedt, Tore¹  Johansson, Jan²  Andersson, Mats²  Jörnvall, Hans² 

[1] Department of Clinical Chemistry, Karolinska Institutet at Danderyd Hospital, S-182 88 Danderyd, Sweden;Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 77 Stockholm, Sweden

关键词: Lipid-binding polypeptide;    Secondary structure;    Saposin-like module;    CD;    circular dichroism;    DPC;    dodecylphosphocholine;    DPPC;    1;    2-dipalmitoyl-sn-glycero-3-phosphocholine;    DTT;    dithiothreitol;    NK;    natural killer;    PA;    palmitic acid;    PG;    phosphatidylglycerol;    SP;    surfactant protein;   

DOI  :  10.1016/0014-5793(95)00268-E

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The tumour-lysing and antimicrobial polypeptide NK-lysin and the pulmonary surfactant-associated polypeptide SP-B exhibit 24% residue identities (49% similarities), including six half-cystine residues in the same disulphide bonding pattern, and similar far-UV circular dichroism spectra corresponding to 45–55% α-helix and 20–25% β-sheet structures. From this, we conclude that the conformations of NK-lysin and SP-B are similar. In contrast, the functional properties of the two proteins are dissimilar: SP-B does not exhibit antibacterial activity and NK-lysin does not significantly effect phospholipid spreading at an air/water interface. Saposins, which solubilize lipids and activate lysosomal hydrolases, the pore-forming amoebapores, and parts of acid sphingomyelinase and acyloxyacylhydrolase, also share 18–27% sequence identities with NK-lysin (and SP-B), including the six conserved half-cystine residues. The inclusion of NK-lysin extends the family of saposin-like polypeptides, all members of which appear to interact with lipids. Strictly conserved structural features with implications for helix topology and lipid interactions are observed.

【 授权许可】

Unknown