Interdependence of phospholipid specificity and calcium binding in annexin I as shown by site-directed mutagenesis.
We have mutated the lysine 128 of domain II of annexin I, which flanks a putative calcium-binding loop, into a glutamic acid residue. The properties of the mutated recombinant protein were compared to those of the wild-type recombinant protein. A change in the isotherm of calcium binding in the presence of lipids was observed. A slight decrease in the affinity for lipids was evident. When tested for the vesicle aggregation property, the mutation induced a change in lipid specificity; unlike the wild-type protein, the mutant protein aggregates vesicles containing phosphatidylserine plus phosphatidylethanolamine better than vesicles containing only phosphatidylserine. These experiments are in agreement with a model which suggests that a lipid molecule is inserted into the calcium-binding loop of annexin I and that the conserved lysine residue is involved in the specificity of annexins for anionic phospholipids.
Travé
G
G
INSERM U-65, Departement de Biologie Santé, Université Montpellier II, France.
Quignard
J F
JF
Lionne
C
C
Sri Widada
J
J
Liautard
J P
JP
D000595:Amino Acid Sequence; D017305:Annexin A1 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D004252:DNA Mutational Analysis; D008081:Liposomes / Q000378:metabolism; D008239:Lysine / Q000235:genetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010714:Phosphatidylethanolamines / Q000494:pharmacology; D010718:Phosphatidylserines / Q000494:pharmacology; D010743:Phospholipids / Q000378:metabolism*; D011485:Protein Binding; D011994:Recombinant Proteins / Q000378:metabolism; D013329:Structure-Activity Relationship
D017305:Annexin A1; D008081:Liposomes; D010714:Phosphatidylethanolamines; D010718:Phosphatidylserines; D010743:Phospholipids; D011994:Recombinant Proteins; D008239:Lysine; D002118:Calcium