 |
PDBsum entry 1bc3
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Calcium-binding protein
|
PDB id
|
|
|
|
1bc3
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
References listed in PDB file
|
|
|
Key reference
|
|
|
Title
|
|
Mutational and crystallographic analyses of interfacial residues in annexin V suggest direct interactions with phospholipid membrane components.
|
|
|
Authors
|
|
B.Campos,
Y.D.Mo,
T.R.Mealy,
C.W.Li,
M.A.Swairjo,
C.Balch,
J.F.Head,
G.Retzinger,
J.R.Dedman,
B.A.Seaton.
|
|
|
Ref.
|
|
Biochemistry, 1998,
37,
8004-8010.
[DOI no: ]
|
|
|
PubMed id
|
|
|
|
|
|
Abstract
|
|
|
Annexin V belongs to a family of eukaryotic calcium-dependent membrane-binding
proteins. The calcium-binding sites at the annexin-membrane interface have been
investigated in some detail; however, little is known about the functional roles
of highly conserved interfacial residues that do not coordinate calcium
themselves. In the present study, the importance of tryptophan 185, and
threonine or serine at positions 72, 144, 228, and 303, in rat annexin V is
investigated by site-directed mutagenesis, X-ray crystallography, and functional
assays. The high-resolution crystal structures of the mutants show that the
mutations do not cause structural perturbations of the annexin molecule itself
or disappearance of bound calcium ions from calcium-binding sites. The assays
indicate that relative to wild-type annexin V, loss of the methyl substituent at
position 72 (Thr72-->Ser) has no effect while loss of the hydroxyl group
(Thr72-->Ala or Thr72-->Lys) causes reduction of membrane binding.
Multiple lysine substitutions (e.g., Thr72,Ser144,Ser228,Ser303-->Lys) have a
greater adverse effect than the single lysine mutation, suggesting that in
annexin V the introduction of potentially favorable electrostatic interactions
between the lysine side chains and the net negatively charged membrane surface
is not sufficient to overcome the loss of the hydroxyl side chains. Replacement
of the unique tryptophan, Trp185, by alanine similarly decreases membrane
binding affinity. Taken together, the data suggest that the side chains mutated
in this study contribute to phospholipid binding and participate directly in
intermolecular contacts with phospholipid membrane components.
|
|
|
|
|
|
|
