2N8Y

Holo form of Calmodulin-Like Domain of Human Non-Muscle alpha-actinin 1

Summary for 2N8Y

• Entry DOI: 10.2210/pdb2n8y/pdb
• Related: 2N8Z
• NMR Information: BMRB: 25870
• Descriptor: Alpha-actinin-1, CALCIUM ION (2 entities in total)
• Functional Keywords: calcium binding protein
• Biological source: Homo sapiens (human)
• Cellular location: Cytoplasm, cytoskeleton : P12814
• Total number of polymer chains: 1
• Total formula weight: 17026.85

Authors

Drmota Prebil, S.,Slapsak, U.,de Almeida Ribeiro, E.,Pavsic, M.,Ilc, G.,Zielinska, K.,Hartl, M.,Backman, L.,Plavec, J.,Lenarcic, B.,Djinovic-Carugo, K. (deposition date: 2015-10-28, release date: 2016-06-29, Last modification date: 2024-05-15)

Primary citation

Drmota Prebil, S.,Slapsak, U.,Pavsic, M.,Ilc, G.,Puz, V.,de Almeida Ribeiro, E.,Anrather, D.,Hartl, M.,Backman, L.,Plavec, J.,Lenarcic, B.,Djinovic-Carugo, K.
Structure and calcium-binding studies of calmodulin-like domain of human non-muscle alpha-actinin-1.
Sci Rep, 6:27383-27383, 2016

PubMed Abstract: The activity of several cytosolic proteins critically depends on the concentration of calcium ions. One important intracellular calcium-sensing protein is α-actinin-1, the major actin crosslinking protein in focal adhesions and stress fibers. The actin crosslinking activity of α-actinin-1 has been proposed to be negatively regulated by calcium, but the underlying molecular mechanisms are poorly understood. To address this, we determined the first high-resolution NMR structure of its functional calmodulin-like domain (CaMD) in calcium-bound and calcium-free form. These structures reveal that in the absence of calcium, CaMD displays a conformationally flexible ensemble that undergoes a structural change upon calcium binding, leading to limited rotation of the N- and C-terminal lobes around the connecting linker and consequent stabilization of the calcium-loaded structure. Mutagenesis experiments, coupled with mass-spectrometry and isothermal calorimetry data designed to validate the calcium binding stoichiometry and binding site, showed that human non-muscle α-actinin-1 binds a single calcium ion within the N-terminal lobe. Finally, based on our structural data and analogy with other α-actinins, we provide a structural model of regulation of the actin crosslinking activity of α-actinin-1 where calcium induced structural stabilisation causes fastening of the juxtaposed actin binding domain, leading to impaired capacity to crosslink actin.

PubMed: 27272015
DOI: 10.1038/srep27383

Experimental method

SOLUTION NMR