The central loop of Escherichia coli glutamine synthetase is flexible and functionally passive.

@article{Pearson2005TheCL,
  title={The central loop of Escherichia coli glutamine synthetase is flexible and functionally passive.},
  author={Josh T. Pearson and Michael J Dabrowski and Irene Y. Kung and William M Atkins},
  journal={Archives of biochemistry and biophysics},
  year={2005},
  volume={436 2},
  pages={397-405}
}
Bacterial glutamine synthetases (GSs) are dodecameric aggregates comprised of two face-to-face hexameric rings, which form a cylindrical aqueous channel. Available crystal structures indicate that each subunit provides a 'central loop' that protrudes into this channel. Residues on either side of this loop contribute directly to substrate or metal ion cofactor binding. Although it has been suggested that this conspicuous structural feature may be functionally important, a systematic structure… CONTINUE READING