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Published on: September 17, 2017
Structural studies on the second Mycobacterium smegmatis Dps: invariant and variable features of structure, assembly
Siddhartha Roy1, Ramachandran Saraswathi, Dipankar Chatterji
1Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India.
Journal of Molecular Biology
|December 7, 2007
Summary
Researchers identified a new DNA binding protein, MsDps2, in Mycobacterium smegmatis. Its unique N-terminal tail influences DNA binding and dodecamer stability, differing from MsDps1 and showing varied DNA complexation modes.
Area of Science:
- * Molecular Biology and Structural Biology
- * Bacterial protein structure and function
Background:
- * DNA binding proteins (Dps) are crucial for bacterial stress response.
- * Mycobacterium smegmatis contains multiple Dps proteins with distinct structural features.
- * Understanding Dps variability is key to comprehending bacterial DNA protection mechanisms.
Purpose of the Study:
- * To identify, clone, express, and characterize a second DNA binding protein (MsDps2) from Mycobacterium smegmatis.
- * To determine the crystal structure of MsDps2 and compare it with MsDps1.
- * To investigate the role of MsDps2's N-terminal tail in DNA binding and dodecamer assembly.
Main Methods:
- * Gene identification and cloning from Mycobacterium smegmatis genome.
- * Protein expression and purification.
- * X-ray crystallography for structure determination.
- * Sequence analysis of Dps proteins across bacterial species.
Main Results:
- * MsDps2 shares a dodecameric core with MsDps1 but possesses a distinct N-terminal tail.
- * The N-terminal tail of MsDps2 is crucial for DNA binding and direct dodecamer stabilization.
- * MsDps2 directly forms dodecamers, unlike MsDps1 which requires incubation and an intermediate trimeric stage.
- * Differences in pore structure and DNA sequestration modes were observed between MsDps1 and MsDps2.
- * A survey identified 300 Dps proteins in bacteria, with variations in Dps type and presence.
Conclusions:
- * MsDps2 exhibits unique structural and functional properties compared to MsDps1, particularly regarding its N-terminal tail.
- * The study highlights the diverse mechanisms of DNA binding and complexation employed by Dps proteins.
- * Variations in Dps protein presence and type across bacterial species suggest diverse roles in adaptation and survival.
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