Skip to main content

An alternative N-terminal fold of the intestine-specific annexin A13a induces dimerization and regulates membrane-binding


AUTHORS

McCulloch KM , Yamakawa I , Shifrin DA , McConnell RE , Foegeding NJ , Singh PK , Mao S , Tyska MJ , Iverson TM , . The Journal of biological chemistry. 2019 1 4; 294(10). 3454-3463

ABSTRACT

Annexin proteins function as Ca-dependent regulators of membrane trafficking and repair that may also modulate membrane curvature. Here, using high-resolution confocal imaging, we report that the intestine-specific annexin A13 (ANX A13) localizes to the tips of intestinal microvilli and determined the crystal structure of the ANX A13a isoform to 2.6 Å resolution. The structure revealed that the N terminus exhibits an alternative fold that converts the first two helices and the associated helix-loop-helix motif into a continuous α-helix, as stabilized by a domain-swapped dimer. We also found that the dimer is present in solution and partially occludes the membrane-binding surfaces of annexin, suggesting that dimerization may function as a means for regulating membrane binding. Accordingly, as revealed by binding and cellular localization assays, ANX A13a variants that favor a monomeric state exhibited increased membrane association relative to variants that favor the dimeric form. Together, our findings support a mechanism for how the association of the ANX A13a isoform with the membrane is regulated.



Tags: ,

VIEW MORE EVENTS >