همایش ملی بیوانفورماتیک ایران

صفحه اصلی / 4th international edition and 13th Iranian Conference on Bioinformatics

Bioinformatics investigation of the structure and function of photoprotein mnemiopsin2 following Glutamine 23 substitutions using a site-directed mutagenesis

نویسندگان :

Zahra Karimi Takaromi¹ Vahab Jafarian² Amir Dehghani³ Khosrow Khalifeh⁴ Fateme Khatami⁵

1- University of Azarbaijan Shahid Madani 2- University of Guilan 3- University of Azarbaijan Shahid Madani 4- University of Zanjan 5- University of Guilan

کلمات کلیدی :

Calcium sensitivity،Mnemiopsin 2،Molecular Modeling،Photoprotein،Site-directed Mutagenesis

چکیده :

Ctenophores are bioluminescent marine organisms that are found all over the world. Light emission in these organisms is carried out by Ca2+-regulated photoproteins. Ca2+ is not essential for light emission in these photoproteins(Stepanyuk and Liu, 2013). However, The light-yielding reaction proceeds at a very slow rate in the absence of Ca2+, and the light intensity is increased up to 1 million-fold with the addition of Ca2+(Eremeeva and Vysotski, 2019). One of the main applications of Ca2+-regulated photoproteins, due to their ability to emit light upon binding to calcium, is their use for detecting calcium ions in biological systems(Natashin and Markova, 2014). These photoproteins consist of a single polypeptide chain and are structurally compact and globular(Hematyar and Jafarian, 2022). Mnemiopsin 2 is a Ca2+-regulated photoprotein extracted from Mnemiopsis leidyi. Light emotion in this photoprotein is blue light, by coelenterazine as a substrate in the presence of calcium ions (Hosseinnia and Khalifeh, 2020). Photoprotein mnemiopsin 2 has three active motifs; EF-hand I, III, and IV, which are located in 45–56, 137–148, and 171–182, respectively(Jafarian and Sajedi, 2018). The Q23E mutation was investigated to increase the negative surface charge for enhanced Ca2+ sensitivity in mnemiopsin 2. Therefore, The three-dimensional structure of the mutant was made with the Modeller program V. 10.4, and the best structure was selected and evaluated using ModEval and SAVES. The VADAR and ProtParam servers were used to Evaluate the secondary structure of the protein, structure stability, and physicochemical properties. The Kyte & Doolittle hydropathy plot was obtained using the ProtScale server. Then, the graphical form of the desirable model was drawn using the UCSF Chimera software, and the compactness of the protein's tertiary structure was examined. Finally, the selected mutant model was compared with the native model. The results indicate a decrease in the folding free energy of the protein with the Q23E mutation, and as a result, it is more stable than the wild-type protein. Also In terms of hydrophobicity, it has not changed. It seems that by reducing the isoelectric point of the mutated protein due to the substitution of an acidic amino acid and an increase in the protein's accessible surface area, binding to Ca2+ increases.