title: Effect of pH on the structure, function, and stability of human calcium/calmodulin-dependent protein kinase IV: combined spectroscopic and MD simulation studies.
abstract: Human calcium/calmodulin-dependent protein kinase IV (CAMKIV) is a member of Ser/Thr protein kinase family. It is regulated by the calcium-calmodulin dependent signal through a secondary messenger, Ca(2+), which leads to the activation of its autoinhibited form. The over-expression and mutation in CAMKIV as well as change in Ca(2+) concentration is often associated with numerous neurodegenerative diseases and cancers. We have successfully cloned, expressed, and purified a functionally active kinase domain of human CAMKIV. To observe the effect of different pH conditions on the structural and functional properties of CAMKIV, we have used spectroscopic techniques such as circular diachroism (CD) absorbance and fluorescence. We have observed that within the pH range 5.0-11.5, CAMKIV maintained both its secondary and tertiary structures, along with its function, whereas significant aggregation was observed at acidic pH (2.0-4.5). We have also performed ATPase activity assays under different pH conditions and found a significant correlation between the structure and enzymatic activities of CAMKIV. In-silico validations were further carried out by modeling the 3-dimensional structure of CAMKIV and then subjecting it to molecular dynamics (MD) simulations to understand its conformational behavior in explicit water conditions. A strong correlation between spectroscopic observations and the output of molecular dynamics simulation was observed for CAMKIV.
authors.affiliation: a Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India.
authors.forename: Huma
authors.initials: H
authors.lastname: Naz
authors.affiliation: b Department of Chemistry, Durban University of Technology, Durban-4000, South Africa.
authors.forename: Mohd
authors.initials: M
authors.lastname: Shahbaaz
authors.affiliation: b Department of Chemistry, Durban University of Technology, Durban-4000, South Africa.
authors.forename: Krishna
authors.initials: K
authors.lastname: Bisetty
authors.affiliation: a Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, 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, Jamia Nagar, 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, Jamia Nagar, New Delhi 110025, India.
authors.forename: Md Imtaiyaz
authors.initials: MI
authors.lastname: Hassan
mesh_terms: D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002942:Circular Dichroism; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D006863:Hydrogen-Ion Concentration; D056004:Molecular Dynamics Simulation; D055550:Protein Stability; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013329:Structure-Activity Relationship
chemical_list: D011994:Recombinant Proteins; C517683:CAMK4 protein, human; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4
keywords: calcium/calmodulin-dependent protein kinase IV; effect of pH; effet du pH; kinase activity; molecular dynamics simulation; protéine kinase dépendante du calcium et de la calmoduline IV; relation structure–fonction; simulation de dynamique moléculaire; spectroscopic techniques; structure–function relationship; techniques spectroscopiques