Transcriptional repressor, LexA, regulates the “SOS” response, an indispensable bacterial DNA damage repair machinery. Compared to its E.coli ortholog, LexA from Mycobacterium tuberculosis (Mtb) possesses a unique N-terminal extension of additional 24 amino acids in its DNA binding domain (DBD) and 18 amino acids insertion at its hinge region that connects the DBD to the C-terminal dimerization/autoproteolysis domain. Despite the importance of LexA in “SOS” regulation, Mtb LexA remains poorly characterized and the functional importance of its additional amino acids remained elusive. In addition, the lack of data on kinetic parameters of Mtb LexA-DNA interaction prompted us to perform kinetic analyses of Mtb LexA and its deletion variants using Bio-layer Interferometry (BLI). Mtb LexA is seen to bind to different “SOS” boxes, DNA sequences present in the operator regions of damage-inducible genes, with comparable nanomolar affinity. Deletion of 18 amino acids from the linker region is found to affect DNA binding unlike the deletion of the N-terminal stretch of extra 24 amino acids. The conserved RKG motif has been found to be critical for DNA binding. Overall, this study provides insights into the kinetics of the interaction between Mtb LexA and its target “SOS” boxes. The kinetic parameters obtained for DNA binding of Mtb LexA would be instrumental to clearly understand the mechanism of “SOS” regulation and activation in Mtb.
Research Article|
November 09 2021
Real-time kinetic studies of Mycobacterium tuberculosis LexA-DNA interaction
Chitral Chatterjee;
Chitral Chatterjee
Indian Institute of Technology Kanpur, Kanpur, India
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Soneya Majumdar;
Soneya Majumdar
Indian Institute of Technology Kanpur, Kanpur, India
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Sachin Deshpande;
Sachin Deshpande
Indian Institute of Technology Kanpur, Kanpur, India
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Deepak Pant;
Deepak Pant
Indian Institute of Technology Kanpur, Kanpur, India
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Saravanan Matheshwaran
Indian Institute of Technology Kanpur, Kanpur, India
* Corresponding Author; email: saran@iitk.ac.in
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Publisher: Portland Press Ltd
Received:
June 11 2021
Revision Received:
October 18 2021
Accepted:
October 27 2021
Online ISSN: 1573-4935
Print ISSN: 0144-8463
Copyright 2021 The Author(s)
2021
This is an Accepted Manuscript; not the final Version of Record. You are encouraged to use the final Version of Record that, when published, will replace this manuscript and be freely available under a Creative Commons licence.
Biosci Rep (2021) BSR20211419.
Article history
Received:
June 11 2021
Revision Received:
October 18 2021
Accepted:
October 27 2021
Citation
Chitral Chatterjee, Soneya Majumdar, Sachin Deshpande, Deepak Pant, Saravanan Matheshwaran; Real-time kinetic studies of Mycobacterium tuberculosis LexA-DNA interaction. Biosci Rep 2021; BSR20211419. doi: https://doi.org/10.1042/BCJ20210434
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