Changes in strand 6B and helix B during neuroserpin inhibition: Implication in severity of clinical phenotype

Publication date: Available online 16 January 2020Source: Biochimica et Biophysica Acta (BBA) - Proteins and ProteomicsAuthor(s): Mohammad Farhan Ali, Abhinav Kaushik, Dinesh Gupta, Shoyab Ansari, Mohamad Aman JairajpuriAbstractNeuroserpin (NS) is predominantly expressed in brain and inhibits tissue-type plasminogen activator (tPA) with implications in brain development and memory. Nature of conformational change in pathological variants in strand 6B and helix B of NS that cause a relatively mild to severe epilepsy (and/or dementia) remains largely elusive. MD simulation with wild type (WT) NS, strand 6B and helix B variants indicated that substitution in this region affects the conformation of the strands 5B, 5A and reactive centre loop. Therefore, we designed variants of NS in strand 6B (I46D and F48S) and helix B (A54F, L55A and L55P) to investigate their role in tPA inhibition mechanism and propensity to aggregate. An interaction analysis showed disturbance of a hydrophobic patch centered at strands 5B, 6B and helix B in I46D and F48S but not in A54F, L55A, L55P and WT NS. Purified I46D, F48S and L55P variants showed decrease in fluorescence emission intensity but with similar α-helical content, results of A54F and L55A were comparable to WT NS. Analysis of tPA inhibition showed marginal effect on A54F and L55A variant with tPA-NS complex formation. In contrast, I46D, F48S and L55P variants showed massive decrease in tPA inhibition, with no tPA-NS complex formation. Anal...
Source: Biochimica et Biophysica Acta (BBA) Proteins and Proteomics - Category: Biochemistry Source Type: research