title: Effect of pH on the stability of hemochromatosis factor E: a combined spectroscopic and molecular dynamics simulation-based study.
abstract: Hereditary hemochromatosis is an iron overburden condition, which is mainly governed by hereditary hemochromatosis factor E (HFE), a member of major histocompatibility complex class I. To understand the effect of pH on the structure and stability of HFE, we have cloned, expressed, and purified the HFE in the bacterial system and performed circular dichroism, fluorescence, and absorbance measurements at a wide pH range (pH 3.0-11.0). We found that HFE remains stable in the pH range 7.5-11.0 and gets completely acid denatured at low pH values. In this work, we also analyzed the contribution of salt bridges to the stability of HFE. We further performed molecular dynamics simulations for 80 ns at different pH values. An excellent agreement was observed between results from biophysical and MD simulation studies. At lower pH, HFE undergoes denaturation and may be driven toward a degradation pathway, such as ubiquitination. Hence, HFE is not available to bind again with transferrin receptor1 to negatively regulate iron homeostasis. Further we postulated that, might be low pH of cancerous cells helps them to meet their high iron requirement.
authors.affiliation: a Centre for Interdisciplinary Research in Basic Sciences , Jamia Millia Islamia , New Delhi 110025 , India.
authors.forename: Parvez
authors.initials: P
authors.lastname: Khan
authors.affiliation: b Department of Chemistry , Indian Institute of Technology Delhi , New Delhi 110016 , India.
authors.forename: Ashutosh
authors.initials: A
authors.lastname: Shandilya
authors.affiliation: b Department of Chemistry , Indian Institute of Technology Delhi , New Delhi 110016 , India.
authors.forename: B
authors.initials: B
authors.lastname: Jayaram
authors.affiliation: a Centre for Interdisciplinary Research in Basic Sciences , Jamia Millia Islamia , New Delhi 110025 , India.
authors.forename: Asimul
authors.initials: A
authors.lastname: Islam
authors.affiliation: a Centre for Interdisciplinary Research in Basic Sciences , Jamia Millia Islamia , New Delhi 110025 , India.
authors.forename: Faizan
authors.initials: F
authors.lastname: Ahmad
authors.affiliation: a Centre for Interdisciplinary Research in Basic Sciences , Jamia Millia Islamia , New Delhi 110025 , India.
authors.forename: Md Imtaiyaz
authors.initials: MI
authors.lastname: Hassan
mesh_terms: D020816:Amino Acid Motifs; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D005822:Genetic Vectors / Q000737:chemistry / Q000378:metabolism; D000071020:Hemochromatosis Protein / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D056004:Molecular Dynamics Simulation; D000072756:Protein Conformation, alpha-Helical; D000072757:Protein Conformation, beta-Strand; D011489:Protein Denaturation; D054730:Protein Interaction Domains and Motifs; D055550:Protein Stability; D059748:Proteolysis; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013816:Thermodynamics
chemical_list: C103673:HFE protein, human; D000071020:Hemochromatosis Protein; D011994:Recombinant Proteins
keywords: hemochromatosis factor E; hereditary hemochromatosis; iron-homeostasis; molecular dynamics simulations; pH-induced denaturation