6zt3 | pdb_00006zt3
N-terminal 47 kDa fragment of the Mycobacterium smegmatis DNA Gyrase B subunit complexed with ADPNP
Structural highlights
Function[GYRB_MYCS2] A type II topoisomerase that negatively supercoils closed circular double-stranded (ds) DNA in an ATP-dependent manner (PubMed:8878580) to modulate DNA topology and maintain chromosomes in an underwound state. Negative supercoiling favors strand separation, and DNA replication, transcription, recombination and repair, all of which involve strand separation. Also able to catalyze the interconversion of other topological isomers of dsDNA rings, including catenanes and knotted rings. Type II topoisomerases break and join 2 DNA strands simultaneously in an ATP-dependent manner.[HAMAP-Rule:MF_01898][1] Publication Abstract from PubMedDNA gyrase, a type II topoisomerase, introduces negative supercoils into DNA using ATP hydrolysis. The highly effective gyrase-targeted drugs, fluoroquinolones (FQs), interrupt gyrase by stabilizing a DNA-cleavage complex, a transient intermediate in the supercoiling cycle, leading to double-stranded DNA breaks. MfpA, a pentapeptide-repeat protein in mycobacteria, protects gyrase from FQs, but its molecular mechanism remains unknown. Here, we show that Mycobacterium smegmatis MfpA (MsMfpA) inhibits negative supercoiling by M. smegmatis gyrase (Msgyrase) in the absence of FQs, while in their presence, MsMfpA decreases FQ-induced DNA cleavage, protecting the enzyme from these drugs. MsMfpA stimulates the ATPase activity of Msgyrase by directly interacting with the ATPase domain (MsGyrB47), which was confirmed through X-ray crystallography of the MsMfpA-MsGyrB47 complex, and mutational analysis, demonstrating that MsMfpA mimics a T (transported) DNA segment. These data reveal the molecular mechanism whereby MfpA modulates the activity of gyrase and may provide a general molecular basis for the action of other pentapeptide-repeat proteins. The pentapeptide-repeat protein, MfpA, interacts with mycobacterial DNA gyrase as a DNA T-segment mimic.,Feng L, Mundy JEA, Stevenson CEM, Mitchenall LA, Lawson DM, Mi K, Maxwell A Proc Natl Acad Sci U S A. 2021 Mar 16;118(11). pii: 2016705118. doi:, 10.1073/pnas.2016705118. PMID:33836580[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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