1I4A

CRYSTAL STRUCTURE OF PHOSPHORYLATION-MIMICKING MUTANT T6D OF ANNEXIN IV

Summary for 1I4A

• Entry DOI: 10.2210/pdb1i4a/pdb
• Descriptor: ANNEXIN IV, CALCIUM ION, SULFATE ION, ... (4 entities in total)
• Functional Keywords: calcium-binding, membrane-binding, phosphorylation mutant, metal binding protein
• Biological source: Bos taurus (cattle)
• Total number of polymer chains: 1
• Total formula weight: 35995.81

Authors

Kaetzel, M.A.,Mo, Y.D.,Mealy, T.R.,Campos, B.,Bergsma-Schutter, W.,Brisson, A.,Dedman, J.R.,Seaton, B.A. (deposition date: 2001-02-20, release date: 2001-04-25, Last modification date: 2023-08-09)

Primary citation

Kaetzel, M.A.,Mo, Y.D.,Mealy, T.R.,Campos, B.,Bergsma-Schutter, W.,Brisson, A.,Dedman, J.R.,Seaton, B.A.
Phosphorylation mutants elucidate the mechanism of annexin IV-mediated membrane aggregation.
Biochemistry, 40:4192-4199, 2001

PubMed Abstract: Site-directed mutagenesis, electron microscopy, and X-ray crystallography were used to probe the structural basis of annexin IV-induced membrane aggregation and the inhibition of this property by protein kinase C phosphorylation. Site-directed mutants that either mimic (Thr6Asp, T6D) or prevent (Thr6Ala, T6A) phosphorylation of threonine 6 were produced for these studies and compared with wild-type annexin IV. In vitro assays showed that unmodified wild-type annexin IV and the T6A mutant, but not PKC-phosphorylated wild-type or the T6D mutant, promote vesicle aggregation. Electron crystallographic data of wild-type and T6D annexin IV revealed that, similar to annexin V, the annexin IV proteins form 2D trimer-based ordered arrays on phospholipid monolayers. Cryo-electron microscopic images of junctions formed between lipid vesicles in the presence of wild-type annexin IV indicated a separation distance corresponding to the thickness of two layers of membrane-bound annexin IV. In this orientation, a single layer of WT annexin IV, attached to the outer leaflet of one vesicle, would undergo face-to-face self-association with the annexin layer of a second vesicle. The 2.0-A resolution crystal structure of the T6D mutant showed that the mutation causes release of the N-terminal tail from the protein core. This change would preclude the face-to-face annexin self-association required to aggregate vesicles. The data suggest that reversible complex formation through phosphorylation and dephosphorylation could occur in vivo and play a role in the regulation of vesicle trafficking following changes in physiological states.

PubMed: 11300800
DOI: 10.1021/bi002507s

Experimental method

X-RAY DIFFRACTION (2 Å)