Insights from the Structure of Mycobacterium tuberculosis Topoisomerase I with a Novel Protein Fold
The DNA topoisomerase I enzyme of Mycobacterium tuberculosis (MtTOP1) is essential for the viability of the organism and survival in a murine model. This topoisomerase is being pursued as a novel target for the discovery of new therapeutic agents for the treatment of drug-resistant tuberculosis. In this study, we succeeded in obtaining a structure of MtTOP1 by first predicting that the C-terminal region of MtTOP1 contains four repeated domains that do not involve the Zn-binding tetracysteine motifs seen in the C-terminal domains of Escherichia coli topoisomerase I. A construct (amino acids A2-T704), MtTOP1-704t, that includes the N-terminal domains (D1-D4) and the first predicted C-terminal domain (D5) of MtTOP1 was expressed and found to retain DNA cleavage-religation activity and catalyze single-stranded DNA catenation. MtTOP1-704t was crystallized, and a structure of 2.52 angstrom resolution limit was obtained. The structure of the MtTOP1 N-terminal domains has features that have not been observed in other previously available bacterial topoisomerase I crystal structures. The first C-terminal domain D5 forms a novel protein fold of a four-stranded antiparallel beta-sheet stabilized by a crossing-over alpha-helix. Since there is only one type IA topoisomerase present in Mycobacteriaceae and related Actinobacteria, this subfamily of type IA topoisomerase may be required for multiple functions in DNA replication, transcription, recombination, and repair. The unique structural features observed for MtTOP1 may allow these topoisomerase I enzymes to carry out physiological functions associated with topoisomerase III enzyme in other bacteria.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- National Institutes of Health (NIH); USDOE Office of Science - Office of Biological and Environmental Research
- DOE Contract Number:
- AC02-06CH11357
- OSTI ID:
- 1251611
- Journal Information:
- Journal of Molecular Biology, Vol. 428, Issue 1; ISSN 0022-2836
- Publisher:
- Elsevier
- Country of Publication:
- United States
- Language:
- English
Similar Records
Mechanistic insights from structure of Mycobacterium smegmatis topoisomerase I with ssDNA bound to both N- and C-terminal domains
Regulation of the catalytic cycle of topoisomerase II