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MksEF Accessory Proteins Inhibit MksB ATPase Activity and Modulate DNA Substrate Binding
Pratibha, Kumari and Shamila Minnu, K. C. and Teasha, Biswas and Vinayak, Hegde and Umesh, Appaiah and Dharma Prasad, M. and Kunal, Sharan and Dhabaleswar, Patra and Ravi, Kumar (2025) MksEF Accessory Proteins Inhibit MksB ATPase Activity and Modulate DNA Substrate Binding. Biochemistry, 64. pp. 4067-4080.
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Abstract
Chromosome organization and segregation are fundamental processes across all domains of life. In bacteria, the mechanisms governing nucleoid organization remain poorly under- stood. This study investigates the function of an alternative structural maintenance of chromosomes (SMC) complex, MksBEF, in Mycobacterium smegmatis. We show that MksB, the SMC subunit of the complex, binds DNA and plays a crucial role in local chromosome organization, a function distinct from that of other condensins. We successfully reconstituted the MksBEF complex and determined its stoichiometry as MksB2E4F2 using gel filtration and ultracentrifuga- tion. Gel shift assays and isothermal titration calorimetry reveal that the accessory proteins MksE and MksF interact with MksB and significantly enhance its DNA-binding affinity�an effect not observed in SMC or MukB-associated accessory proteins. Furthermore, ANS-based fluorescence experiments indicate that DNA binding induces structural rearrangements in both MksB alone and the MksBEF complex. Notably, although MksEF enhances the DNA-binding affinity of MksB, it also markedly suppresses its ATPase activity, a unique regulatory mechanism distinct from other SMC complexes. These findings provide mechanistic insights into how MksE and MksF modulate MksB activity, advancing our understanding of chromosome dynamics in mycobacteria.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | MksEF Accessory Proteins, DNA Substrate, SMC proteins |
| Subjects: | 600 Technology > 08 Food technology > 16 Nutritive value > 03 Proteins |
| Divisions: | Molecular Nutrition |
| Depositing User: | Somashekar K S |
| Date Deposited: | 21 Nov 2025 06:48 |
| Last Modified: | 21 Nov 2025 06:48 |
| URI: | http://ir.cftri.res.in/id/eprint/20101 |
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