Structural Determinant of the Vesicle Aggregation Activity of Annexin I

• Published in: Biochemistry (Easton) Vol. 38; no. 42; pp. 14094 - 14100
• Main Authors: Bitto, Eduard, Cho, Wonhwa
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 19.10.1999
• Subjects: Agglomeration; Amino Acid Sequence; Amino acids; Annexin A1 - chemistry; Annexin A1 - genetics; Annexin A1 - metabolism; Binding energy; Biological membranes; Chemical bonds; Chemical reactions; Conformations; Humans; Lysine - genetics; Lysine - metabolism; Membrane Proteins - chemistry; Membrane Proteins - genetics; Membrane Proteins - metabolism; Molecular Sequence Data; Mutagenesis; Mutagenesis, Site-Directed; Peptide Fragments - chemistry; Peptide Fragments - genetics; Peptide Fragments - metabolism; Phospholipids - chemistry; Phospholipids - metabolism; Protein Conformation; Recombinant Fusion Proteins - chemistry; Recombinant Fusion Proteins - metabolism; Sequence Deletion; Serine - genetics; Serine - metabolism; Structure-Activity Relationship
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi990457p

Some annexins, including annexins I, II, IV, and VII, can promote membrane aggregation. To identify amino acids involved in annexin I-mediated membrane aggregation, we generated truncated mutants of human annexin I lacking various parts of the amino terminus. The in vitro vesicle binding and aggregation activities of these mutants indicated that both the amino-terminal region of annexin I spanning residues 26−29 and the carboxy-terminal core are involved in membrane aggregation. This notion was further supported by the finding that a chimera composed of residues 24−35 of annexin I and the core of annexin V has vesicle aggregation activity that is significantly higher than that of annexin V but lower than that of annexin I. Further site-specific mutations in the amino-terminal region of annexin I indicated that Lys-26 and Lys-29 are essential for its membrane aggregation activity. The comparison of tryptic digest patterns of free and vesicle-bound wild type and K29E mutant suggests that a primary role of Lys-26 and Lys-29 is to induce and stabilize an active conformation of annexin I for vesicle aggregation.