DNA Gyrase presentation

BSM3201-1 MOLECULAR BIOLOGY

Group 1:

• CHAI PEI HONG (211616)
• sharanya shree a/p subbarao (212651)
• toh xiao wei (213006)
• sabrina chowdhury diya (213745)

TOPOISOMERASE II

START

DNA gyrase in bacteria (topoisomerase II in eukaryotes) relieves the tension by changing the DNA into negatively supercoiled DNA. How does it work？

DNA GYRASE

Supercoiled

If DNA Gyrase inhibited?

Differences between topoisomerase 1 & 2

Introduction

Mechanism

DNA GYRASE

DNA Gyrase: - A type II topoisomerase - Found in the nucleoid region of bacterial cells- Involved in DNA replication and repair - Require 2 ATP molecules - Contain 3 gates: N-gates, DNA-gates, C-gates Function: - involved in the control of topological transitions of DNA- catalyse negative supercoiling (ATP- dependent

INTRODUCTION

How E.Coli can packed so many DNA in its small volume?

+ Info

Unseparated portion becomes more tightly woundOccur when the DNA strands relieves its helical stress by twisting around itself

Positive Supercoiling

Untangling the Knots: Exploring the Mechanism of Topoisomerase

Mechanism of DNA Gyrase

1. DNA gyrase binds to double-stranded DNA
2. Introduces a double-strand breaks
3. Another double-strand will pass through the gap
4. Reseals the double-strand break (require ATP)
5. The strands are releaved from DNA gyrase

Mechanism of DNA Gyrase

• It has the residue of tyrosine and one of the lone pairs of electrons on this oxygen of tyrosine acts as nucleophile and attacks the phosphorus
• Two electron bonds gets shifted on to this oxygen and an oxygen can pick up a hydrogen.
• It covalently bonds to the phosphorus thus breaking its phosphate sugar backbone

Mechanism of DNA Gyrase

• Dimeric enzyme

(consists of two protein subunits)

• Enzyme which cut the both strands of double helix of DNA

(generate double-strand breaks)

Topoisomerase II

Topoisomerase I

Differences between Topoisomerase I and Topoisomerase II

• Monomeric enzyme

(consists of a single protein subunit)

• Enzyme which only cut one of the two strands of double helix of DNA

(generate single-strand breaks)

• Occurs in both eukaryotes and prokaryotes

• Require ATP hydrolysis

Topoisomerase II

Topoisomerase I

Differences between Topoisomerase I and Topoisomerase II

• Occurs in eukaryotes

• Does not require ATP hydrolysis

Unraveling the power of topoisomerase inhibition: Breaking the chains of cancer growth

Topoisomerase Inhibition

• Topoisomerase inhibition primarily occurs by the Inhibition of the religation reaction.

• This leads to the accumulation of DNA breaks, haulting DNA replication and causing apoptosis.

• The most important effect of these inhibitors is to block their target enzyme by binding to the active site, in the catalytic cycle where the enzyme is covalently bound to DNA. (Top-DNA cleavage complex)

Topoisomerases inhibitors act on both type 1 and 2

Inhibition Mechanism

Chemotherapy

These drugs are now widely adminstered against lung cancer, ovarian cancer, testicular cancer and leukemia

Anthracyclins and podophyllotoxinsact as anti-cancer drugs specifically targeting TOP II. Whereas, Camptothecins inhibits TOP 1 activity. Both group of drugs work by preventing the re-sealing of DNA strands

Fluoroquinolones are broad-spectrum potent anti-bacterial agents. The target these drugs are bacterial type 2 topoisomerase( DNA gyrase). Similarly, quinolones target both DNA gyrase and TOP IV

Anti-cancer agent

Anti-bacterial agent

This inhibition mechanism provides key to drug development.Depending on the organism and type of topoisomerase being targeted; the inhibitors can work as :

Application

REFERENCES

• Reece R. J., Maxwell A. (1991). DNA gyrase: Structure and function. Crit. Rev. Biochem. Mol. Biol. 26 335–375. 10.3109/10409239109114072
• Gore J, Bryant Z, Stone MD, Nollmann M, Cozzarelli NR, Bustamante C, "Mechanochemical Analysis of DNA Gyrase Using Rotor Bead Tracking", Nature 2006 Jan 5 (Vol. 439): 100-104.
• Sugino A, Cozzarelli NR (July 1980). "The intrinsic ATPase of DNA gyrase". The Journal of Biological Chemistry. 255 (13): 6299–306. doi:10.1016/S0021-9258(18)43737-4. PMID 6248518.
• Lakna. (2019). What is the difference between topoisomerase I and II? Retrieved from https://pediaa.com/what-is-the-difference-between-topoisomerase-i-and-ii/
• Kuroda, S., Kagawa, S., & Fujiwara, T. (2014). Selectively Replicating Oncolytic Adenoviruses Combined with Chemotherapy, Radiotherapy, or Molecular Targeted Therapy for Treatment of Human Cancers. Gene Therapy of Cancer (Third Edition), 171-183. https://doi.org/10.1016/B978-0-12-394295-1.00012-3
• Pommier, Y. (2008). Camptothecins. In: Offermanns, S., Rosenthal, W. (eds) Encyclopedia of Molecular Pharmacology. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-38918-7_251
• Bardal, S. K., Waechter, J. E., & Martin, D. S. (2011). Neoplasia. Applied Pharmacology, 305-324. https://doi.org/10.1016/B978-1-4377-0310-8.00020-8

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