7EWC

Mycobacterium tuberculosis HigA2 (Form I)

Summary for 7EWC

• Entry DOI: 10.2210/pdb7ewc/pdb
• Descriptor: Putative antitoxin HigA2 (2 entities in total)
• Functional Keywords: antitoxin, higa2, dna binding protein
• Biological source: Mycobacterium tuberculosis (strain ATCC 25618 / H37Rv)
• Total number of polymer chains: 4
• Total formula weight: 45239.71

Authors

Kim, H.J. (deposition date: 2021-05-25, release date: 2022-03-02, Last modification date: 2023-11-29)

Primary citation

Richardson, W.,Kang, G.W.,Lee, H.J.,Kwon, K.M.,Kim, S.,Kim, H.J.
Chasing the structural diversity of the transcription regulator Mycobacterium tuberculosis HigA2.
Iucrj, 8:823-832, 2021

PubMed Abstract: Transcription factors are the primary regulators of gene expression and recognize specific DNA sequences under diverse physiological conditions. Although they are vital for many important cellular processes, it remains unclear when and how transcription factors and DNA interact. The antitoxin from a toxin-antitoxin system is an example of negative transcriptional autoregulation: during expression of the cognate toxin it is suppressed through binding to a specific DNA sequence. In the present study, the antitoxin HigA2 from M37Rv was structurally examined. The crystal structure of HigA2 comprises three sections: an N-terminal autocleavage region, an α-helix bundle which contains an HTH motif, and a C-terminal β-lid. The N-terminal region is responsible for toxin binding, but was shown to cleave spontaneously in its absence. The HTH motif performs a key role in DNA binding, with the C-terminal β-lid influencing the interaction by mediating the distance between the motifs. However, HigA2 exhibits a unique coordination of the HTH motif and no DNA-binding activity is detected. Three crystal structures of HigA2 show a flexible alignment of the HTH motif, which implies that the motif undergoes structural rearrangement to interact with DNA. This study reveals the molecular mechanisms of how transcription factors interact with partner proteins or DNA.

PubMed: 34584743
DOI: 10.1107/S2052252521007715

Experimental method

X-RAY DIFFRACTION (2.05 Å)