2tct

THE COMPLEX FORMED BETWEEN TET REPRESSOR AND TETRACYCLINE-MG2+ REVEALS MECHANISM OF ANTIBIOTIC RESISTANCE

spinqualitylabelsall models 2tct, resolution 2.10Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2tct is a 1 chain structure with sequence from "bacillus_coli"_migula_1895 "bacillus coli" migula 1895. This structure supersedes the now removed PDB entry 1tct. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CTC, MG Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [TETR4_ECOLX] TetR is the repressor of the tetracycline resistance element; its N-terminal region forms a helix-turn-helix structure and binds DNA. Binding of tetracycline to TetR reduces the repressor affinity for the tetracycline resistance gene (tetA) promoter operator sites. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed In recent years Gram-negative bacteria have developed several resistance mechanisms against the broad-spectrum antibiotic tetracycline (Tc). The most abundant mechanism involves a membrane-associated protein (TetA) that exports the antibiotic out of the bacterial cell before it can attach to the ribosomes and inhibit polypeptide elongation. The expression of the TetA protein is regulated by the Tet repressor (TetR). It occurs as a homodimer and binds with two alpha-helix-turn-alpha-helix motifs (HTH) to two tandemly orientated DNA operators, thereby blocking the expression of the associated genes, one encoding for TetA and the other for TetR. If Tc in complex with a divalent cation binds to TetR, a conformational change occurs and the induced TetR is then unable to bind to DNA. TetR of class D, TEtRD, was cocrystallized with tetracycline (7HTc) and Mg2+ in space group I4(1)22 and studied by X-ray diffraction. One TetRD monomer occupies the crystal asymmetric unit, and the dimer is formed by a crystallographic 2-fold rotation. The crystal structure was determined by multiple isomorphous replacement at 2.5 A resolution, and on this basis the structure of the nearly isomorphous complex with 7-chlorotetracycline, TetRD/(Mg 7CITc)+, has been refined to an R-factor of 18.3% using all reflections to 2.1 A resolution. TetRD folds into ten alpha-helices with connecting turns and loops. The N-terminal three alpha-helices of the repressor form the DNA-binding domain, including the HTH with an inverse orientation compared with HTH in other DNA-binding proteins. The distance of 39 A between the two recognition helices explains the inability of the induced TetR to bind to B-form DNA. The core of the protein is formed by helices alpha 5 to alpha 10. It is responsible for dimerization and contains, for each monomer, a binding pocket that accommodates Tc in the presence of a divalent cation. The structure of the TetRD/(Mg 7CITc)+ complex reveals the octahedral coordination of Mg2+ by Tc (chelating O-11, and O-12), His100 N epsilon and by three water molecules; in addition there is an extended network of hydrogen bonding and van der Waals interactions formed between 7CITc and TetR. The detailed view of the Tc-binding pocket and the interactions between the antibiotic and the repressor offers the first solid basis for rational tetracycline design, with the aim of circumventing resistance. The complex formed between Tet repressor and tetracycline-Mg2+ reveals mechanism of antibiotic resistance.,Kisker C, Hinrichs W, Tovar K, Hillen W, Saenger W J Mol Biol. 1995 Mar 24;247(2):260-80. PMID:7707374 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Tetracycline repressor protein

Proteopedia Page Contributors and Editors (what is this?)

OCA