Genetic experiments with full length AraC and biophysical experiments with its dimerization domain plus linker suggest that arabinose binding to the dimerization domain changes the properties of the inter-domain linker which connects the dimerization domain to the DNA binding domain via interactions that do not depend on the DNA binding domain. Normal AraC function was found to tolerate considerable linker sequence alteration excepting proline substitutions. The proline substitutions partially activate transcription even in the absence of arabinose and hint that a structural shift between helix and coil may be involved. To permit fluorescence anisotropy measurements that could detect arabinose-dependent dynamic differences in the linkers, IAEDANS was conjugated to a cysteine residue substituted at the end of the linker of dimerization domain. Arabinose, but not other sugars, decreased the steady-state anisotropy, indicating either an increase in mobility and/or an increase in the fluorescence lifetime of the IAEDANS. Time-resolved fluorescence measurements showed that the arabinose-induced anisotropy decrease did not result from an increase in the excited-state lifetime. Hence arabinose-induced decreases in anisotropy appear to result from increased tumbling of the fluorophore. Arabinose did not decrease the anisotropy in mutants incapable of binding arabinose nor did it alter the anisotropy when IAEDANS was conjugated elsewhere in the dimerization domain. Experiments with heterodimers of the dimerization domain showed that the binding of arabinose to one subunit of the dimer decreases the fluorescence anisotropy of only a fluorophore on the linker of the other subunit.
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http://dx.doi.org/10.1002/prot.24990 | DOI Listing |
J Biol Chem
December 2024
Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada. Electronic address:
Calpain-3 is an intracellular Ca-dependent cysteine protease abundant in skeletal muscle. Loss-of-function mutations in its single-copy gene cause a dystrophy of the limb-girdle muscles. These mutations, of which there are over 500 in humans, are spread all along this 94-kDa multi-domain protein that includes three 40+-residue sequences (NS, IS1, and IS2).
View Article and Find Full Text PDFProtein Sci
January 2025
Department of Physics, University of Toronto, Toronto, Ontario, Canada.
The point mutation N642H of the signal transducer and activator of transcription 5B (STAT5B) protein is associated with aggressive and drug-resistant forms of leukemia. This mutation is thought to promote cancer due to hyperactivation of STAT5B caused by increased stability of the active, parallel dimer state. However, the molecular mechanism leading to this stabilization is not well understood as there is currently no structure of the parallel dimer.
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December 2024
Department of Immunology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran; Molecular and Cell Biology Research Center (MCBRC), School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran. Electronic address:
Background: Tumor cells exploit epidermal growth factor receptor (EGFR) family to develop resistance against therapeutic antibodies, such as Herceptin. Upon ligand binding, dimerization between EGFR and HER2 is one of the most important causes of treatment failure in breast cancer and other cancers expressing EGFR and HER2. The aim of this study was to develop and evaluate the function of a human recombinant single-chain variable fragment (scFv) antibody against the dimerization domain of EGFR to inhibit its interaction with other members of the epidermal growth factor receptor family, especially HER2.
View Article and Find Full Text PDFCell
December 2024
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China; Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China. Electronic address:
ATP-binding cassette (ABC) transporter subfamily H is only identified in arthropods and zebrafish. It transports lipids and is related to insecticide resistance. However, the precise mechanisms of its functions remain elusive.
View Article and Find Full Text PDFJ Med Genet
December 2024
Institute of Neuroanatomy, Medical Faculty, University of Bonn, Bonn, Germany.
Background: Previous studies in mouse, and zebrafish embryos show strong expression in progenitor cells of neuronal and neural crest tissues suggesting its involvement in neural crest specification. However, the role of human transcription factor activator protein 2 ( in human embryonic central nervous system (CNS), orofacial and maxillofacial development is unknown.
Methods: Through a collaborative work, exome survey was performed in families with congenital CNS, orofacial and maxillofacial anomalies.
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