5h5m
Crystal structure of HMP-1 M domain
Structural highlights
FunctionHMP1_CAEEL Required for cell migration during body enclosure and cell shape changes during body elongation (PubMed:9531567). Required for proper localization of other junctional components, such as pac-1 (PubMed:25938815).[1] [2] Publication Abstract from PubMedIntercellular epithelial junctions formed by classical cadherins, beta-catenin, and the actin-binding protein alpha-catenin link the actin cytoskeletons of adjacent cells into a structural continuum. These assemblies transmit forces through the tissue and respond to intracellular and extracellular signals. However, the mechanisms of junctional assembly and regulation are poorly understood. Studies of cadherin-catenin assembly in a number of metazoans have revealed both similarities and unexpected differences in the biochemical properties of the cadherin.catenin complex that likely reflect the developmental and environmental requirements of different tissues and organisms. Here, we report the structural and biochemical characterization of HMP-1, the Caenorhabditis elegans alpha-catenin homolog, and compare it with mammalian alpha-catenin. HMP-1 shares overall similarity in structure and actin-binding properties, but displayed differences in conformational flexibility and allosteric regulation from mammalian alpha-catenin. HMP-1 bound filamentous actin with an affinity in the single micromolar range, even when complexed with the beta-catenin homolog HMP-2 or when present in a complex of HMP-2 and the cadherin homolog HMR-1, indicating that HMP-1 binding to F-actin is not allosterically regulated by the HMP-2.HMR-1 complex. The middle (i.e. M) domain of HMP-1 appeared to be less conformationally flexible than mammalian alpha-catenin, which may underlie the dampened effect of HMP-2 binding on HMP-1 actin-binding activity compared with that of the mammalian homolog. In conclusion, our data indicate that HMP-1 constitutively binds beta-catenin and F-actin, and although the overall structure and function of HMP-1 and related alpha-catenins are similar, the vertebrate proteins appear to be under more complex conformational regulation. Structural and functional characterization of Caenorhabditis elegans alpha-catenin reveals constitutive binding to beta-catenin and F-actin.,Kang H, Bang I, Jin KS, Lee B, Lee J, Shao X, Heier JA, Kwiatkowski AV, Nelson WJ, Hardin J, Weis WI, Choi HJ J Biol Chem. 2017 Apr 28;292(17):7077-7086. doi: 10.1074/jbc.M116.769778. Epub, 2017 Mar 15. PMID:28298447[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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