Zanjan, Iran | Monday, September 25, 2017   


Institute for Advanced Studies in Basic Sciences (IASBS)

No. 444, Prof. Yousef Sobouti Blvd.

P. O. Box 45195-1159 Zanjan Iran

F: (+98) 24 3315-5142

T: (+98) 24 33151

W: iasbs.ac.ir


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Home>Department of Biological Sciences>
Department of Biological Sciences
 
 
Shekufeh Zareian  
Assistant Professor
Room: Building
Tel: 33153311
Fax:
Email:
Personal Homepage

Education:

Rice University, Bioscience Research Collaborative, Houston, TX, USA, Jul 2011 - Apr 2012 Visiting Scholar, Metabolic Engieenring for Biofuel Production

Tarbait Modares University, Tehran, Iran, Sept 2007-Jul 2012  Ph.D., Biochemistry

Tarbiat Modares University, Tehran, Iran, Sept 2004 – Sep 2007 Master of Science, Biochemistry

Tarbiat Moalem University of Tehran, Iran, Sept 2000 –Jun 2004 Bachelor of Science, Biology


Research interests:

Protein Engineering

Protein Structure

Enzyme Kinetics

Enzyme Immobilization

Drug Design

Metabolic Engineering for Production of Biofuels and  Pharmaceuticals

Metabolism

Synthetic Biology


Teaching Experiences:


1. Biophysics, topics covered in this course include; Protein physics and nucleic acids structure and function

2. Biochemistry, topics covered in this course include; Proteins, Nucleic acids, Carbohydrates, Fatty acids and Principles of metabolism

3. Proteins and Nucleic Acids Structure and Function

4. Principles of Enzymology

‌5. Biochemistry of Hormones

 

 


Some neat stuff:

http://www.reed.edu/persian-calligraphy/fa/


Research area:

Enzymology, Biotechnology


Publications:
Journal
1- Mohammadi , M., Zareian, S., Khajeh, K., "Conversion of non-allosteric methylglyoxal synthase into a homotropic allosteric enzyme by C-terminal deletion", Journal of Molecular Catalysis B: Enzymatic , 1-27, (2014).

Abstract:
Our previous study revealed that the Hill coefficient of E. coli methylglyoxal synthase (EMGS) is higher than what we have calculated for MGS from Thermus sp. GH5 (TMGS). Amino acid sequence alignment of EMGS and TMGS shows that key residues of allosteric pathways in EMGS exist in TMGS as well, except Arg150 which plays a crucial role in forming a salt bridge with Asp20 in the neighboring subunit and consequently transfers the allosteric signal between the subunits. To equalize allosteric pathway in EMGS with TMGS, ten amino acid residues, containing Arg150, are omitted from the EMGS C-terminal tail. The resulting recombinant enzyme (EMGS-ΔC) surprisingly shows homotropic cooperative behavior in presence of dihydroxyacetone phosphate. Structural studies and irreversible thermoinactivation data shows EMGS-ΔC is not only more flexible but also less stable compared to wild-type EMGS. These data suggest EMGS C-terminal tail may play an important role in allosteric behavior and stability of wild-type EMGS and thus indicating that the homotropic cooperatvity is arisen by binding of the substrate which pushes the pre-existing equilibrium between the relatively inactive (RI) and relatively active (RA) conformations.
2- Mohammadi , M., Atabakhshi Kashi , M., Zareian , S., Mirshahi , M., Khajeh, K., "Remarkable improvement of methylglyoxal synthase thermostability by His-His interaction", Appl Biochem Biotechnol, 172: (1), 157-167, (2014).

Abstract:
Lately it has been proposed that interaction between two positively charged side chains can stabilize the folded state of proteins. To further explore this point, we studied the effect of histidine-histidine interactions on thermostability of methylglyoxal synthase from Thermus sp. GH5 (TMGS). The crystal structure of TMGS revealed that His23, Arg22, and Phe19 are in close distance and form a surface loop. Here, two modified enzymes were produced by site-directed mutagenesis (SDM); one of them, one histidine (TMGS-HH(O)), and another two histidines (TMGS-HHH(O)) were inserted between Arg22 and His23 (H(O)). In comparison with the wild type, TMGS-HH(O) thermostability increased remarkably, whereas TMGS-HHH(O) was very unstable. To explore the role of His23 in the observed phenomenon, the original His23 in TMGS-HHH(O) was replaced with Ala (TMGS-HHA). Our data showed that the half-life of TMGS-HHA decreased in relation to the wild type. However, its half-life increased in comparison with TMGS-HHH(O). These results demonstrated that histidine-histidine interactions at position 23 in TMGS-HH(O) probably have the main role in TMGS thermostability.
3- Shavandi, M., Soheili, M., Zareian, S., Akbari, N., Khajeh, K., "Gene cloning, overexpression, purification and characterization of dibenzothiophene monooxygenase and desulfinase from Gordonia alkanivorans RIPI90A", Journal of Petroleum Science and Technology , 3: (2), 57-64, (2013).

Abstract:
The biodesulfurization (BDS) of sulfur compounds in fossil fuels is a process to reduce sulfur dioxide emissions that cause environmental pollution. Gordonia alkanivorans RIPI90A is able to convert dibenzothiophene, an organic sulfur compound in petroleum, to 2-hydroxybiphenyl (2-HBP) in 4S pathway. In this study, (DBT), DszA and DszB, DBT sulfone monooxygenase, and desulfinase were respectively isolated from G. alkanivorans RIPI90A. PCR amplified fragments were obtained by using primers designed based on known sequences from G. alkanivorans RIPI90A. They are identified as dszA and dszB and have shown high similarity compared to Rhodococcus erythropolis IGTS8 (88% for dszA and 88% for dszB). Subsequently, dszA and dszB genes were expressed under the control of T7 promoter in Escherichia coli. The recombinant proteins were purified to achieve homogeneity using Ni-agarose column chromatography. The molecular mass of the purified DszA and DszB were determined to be 51.9 and 39.2 kDa respectively by using SDS-polyacrylamide gel electrophoresis. DszA showed a Km of 0.14±0.005 mM and a maximal velocity of 0.004±0.0004 mM/min. DszB showed a wide substrate range in a way that all aromatic sulfonates compounds acted as its substrate; as it seemed the active site was suitable for the sulfonated aromatic rings. The Km and Vmax values of DszB were calculated to be 1.81±0.02 mM and 6.55 ± 0.005 µM/min respectively using 4-Amino-3-hydroxy-naphthalene-sulfonic acid as a substrate.
4- Falahati, H., Pazhang, M., Zareian, S., Ghaemi, N., Rofougaran, R., Hofer, A., R.Rezaie, A., Khajeh, K., "Transmitting the allosteric signal in methylglyoxal synthase", Protein Eng. Des. Sel, 26: (4), 445-452, (2013).

Abstract:
The homohexameric enzyme methylglyoxal synthase (MGS) converts dihydroxyacetone phosphate (DHAP) to methylglyoxal and phosphate. This enzyme is allosterically inhibited by phosphate. The allosteric signal induced by phosphate in MGS from Thermus sp. GH5 (TMGS) has been tracked by site-directed mutagenesis, from the binding site of phosphate to the pathways that transmit the signal, and finally to the active site which is the receiver of the signal. In TMGS, Ser-55 distinguishes the inhibitory phosphate from the phosphoryl group of the substrate, DHAP, and transmits the allosteric signal through Pro-82, Arg-97 and Val-101 to the active site. Furthermore, the addition of a C-terminal tail to TMGS reinforces the allosteric signal by introducing a new salt bridge between Asp-10 and an Arg in this tail. Lastly, the active site amino acid, Gly-56, is shown to be involved in both allostery and phosphate elimination step from DHAP by TMGS. Interestingly, some of the mutations also trigger homotropic allostery, supporting the hypothesis that allostery is an intrinsic property of all dynamic proteins. The details of the TMGS allosteric network discussed in this study can serve as a model system for understanding the enigmatic allosteric mechanism of other proteins.
5- Zareian, S., Khajeh, K., Pazhang, M., Ranjbar, B., "Rationalization of allosteric pathway in Thermus sp. GH5 methylglyoxal synthase", BMB Rep, 45: (12), 748-753, (2012).

Abstract:
A sequence of 10 amino acids at the C-terminus region of methylglyoxal synthase from Escherichia coli (EMGS) provides an arginine, which plays a crucial role in forming a salt bridge with a proximal aspartate residue in the neighboring subunit, consequently transferring the allosteric signal between subunits. In order to verify the role of arginine, the gene encoding MGS from a thermophile species, Thermus sp. GH5 (TMGS) lacking this arginine was cloned with an additional 30 bp sequence at the 3´-end and then expressed in form of a fusion TMGS with a 10 residual segment at the C-terminus (TMGS(+)). The resulting recombinant enzyme showed a significant increase in cooperativity towards phosphate, reflected by a change in the Hill coefficient (nH) from 1.5 to 1.99. Experiments including site directed mutagenesis for Asp-10 in TMGS and TMGS(+), two dimentional structural survey, fluorescence and irreversible thermoinactivation were carried out to confirm this pathway.
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