DNA gyrase subunit A - P0AES4 (GYRA_ECOLI)

 

Protein Feature View of PDB entries mapped to a UniProtKB sequence  

 
Function
A type II topoisomerase that negatively supercoils closed circular double-stranded (ds) DNA in an ATP-dependent manner to maintain chromosomes in an underwound state (PubMed:3031051, PubMed:186775, PubMed:7811004, PubMed:9148951, PubMed:12051842, PubMed:18642932, PubMed:19060136, PubMed:20356737, PubMed:22457353, PubMed:23294697, PubMed:19965760). This makes better substrates for topoisomerase IV (ParC and ParE) which is the main enzyme that unlinks newly replicated chromosomes in E.coli (PubMed:9334322). Gyrase catalyzes the interconversion of other topological isomers of dsDNA rings, including catenanes (PubMed:22457352). Relaxes negatively supercoiled DNA in an ATP-independent manner (PubMed:337300). E.coli gyrase has higher supercoiling activity than many other bacterial gyrases; at comparable concentrations E.coli gyrase introduces more supercoils faster than M.tuberculosis gyrase, while M.tuberculosis gyrase has higher decatenation than supercoiling activity compared to E.coli (PubMed:22457352). E.coli makes 15% more negative supercoils in pBR322 plasmid DNA than S.typhimurium; the S.typhimurium GyrB subunit is toxic in E.coli, while the E.coli copy can be expressed in S.typhimurium even though the 2 subunits have 777/804 residues identical (PubMed:17400739). The enzymatic differences between E.coli gyrase and topoisomerase IV are largely due to the GyrA C-terminal domain (approximately residues 524-841) and specifically the GyrA-box (PubMed:8962066, PubMed:16332690). UniProt
Catalytic Activity
ATP-dependent breakage, passage and rejoining of double-stranded DNA. UniProt
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Subunit Structure
Heterotetramer, composed of two GyrA and two GyrB chains (PubMed:9148951, PubMed:12051842). In the heterotetramer, GyrA contains the active site tyrosine that forms a transient covalent intermediate with the DNA, while GyrB binds cofactors and catalyzes ATP hydrolysis (PubMed:12051842, PubMed:18642932, PubMed:19965760, PubMed:9148951). Can form a 2:2 complex with toxin CcdB in which GyrA is inactive; rejuvenation of GyrA(2)CcdB(2) is effected by CcdA (PubMed:15854646, PubMed:1324324, PubMed:8254658, PubMed:8604132). UniProt
Domain
The C-terminal domain (CTD, approximately residues 535-841) contains 6 tandemly repeated subdomains known as blades, each of which is composed of a 4-stranded antiparallel beta-sheet (PubMed:15897198). The blades form a circular-shaped beta-pinwheel fold arranged in a spiral around a screw axis, to which DNA probably binds, inducing strong positive superhelicity (about 0.8 links/protein) (PubMed:15897198). The non-conserved, C-terminal acidic tail (residues 842-875) regulates wrapping and DNA-binding by the CTD; deletions within the tail show it is autoinhibitory for DNA wrapping and binding, and couples ATP hydrolysis to DNA strand passage (PubMed:22457353). The GyrA-box is a 7 amino acid motif found in the first blade of the CTD which is discriminative for gyrase versus topoisomerase IV activity (PubMed:9426128). The GyrA-box is required for wrapping of DNA around gyrase, and thus is essential for the DNA supercoiling activity but not DNA relaxation or decatenation activities of gyrase (PubMed:16332690). UniProt
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Data in green originates from UniProtKB  
Variation data (sourced from UniProt) shows non-genetic variation from the ExPASy   and dbSNP   websites.
Data in yellow originates from Pfam  , by interacting with the HMMER3 web site  
Data in purple originates from Phosphosite  .
Data in orange originates from the SCOP   (version 1.75) and SCOPe   (version 2.04) classifications.
Data in grey has been calculated using BioJava  . Protein disorder predictions are based on JRONN (Troshin, P. and Barton, G. J. unpublished), a Java implementation of RONN  
  • Red: potentially disorderd region
  • Blue: probably ordered region.
Hydropathy has been calculated using a sliding window of 15 residues and summing up scores from standard hydrophobicity tables.
  • Red: hydrophobic
  • Blue: hydrophilic.
Data in lilac represent the genomic exon structure projected onto the UniProt sequence.
Data in blue originates from PDB
  • Secstruc: Secondary structure projected from representative PDB entries onto the UniProt sequence.
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Data in red indicates combined ranges of Homology Models from the SWISS-MODEL Repository  
The PDB to UniProt mapping is based on the data provided by the EBI SIFTS project. See also Velankar et al., Nucleic Acids Research 33, D262-265 (2005).
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