Image credit: Sathya Srinivasachari, Vikas R. Tiwari, Tripti Kharbanda, Ramanathan Sowdamini, Ramaswamy Subramanian (2023) A dimer between monomers and hexamers—Oligomeric variations in glucosamine-6-phosphate deaminase family. PLoS ONE 18(1): e0271654.  https://doi.org/10.1371/journal.pone.0271654 Figure 3.

Sathya Srinivasachari et al report the crystal structures of Glucosamine-6-phosphate deaminase (NagB) from Haemophilus influenzae (Hi) and Pasturella multocida (Pm) in the Journal PLoS ONE, published January 4, 2023. The Hi-NagB crystal was obtained through vapor diffusion by mixing 0.5 uL of the protein with 0.5 uL of 2% v/v Tacsimate pH 5.0, 0.1 M Sodium citrate tribasic pH 5.6, 16% w/v Polyethylene glycol 3,350 (PEG/Ion 2 Reagent# 31), and 0. M Strontium chloride hexahydrate (as an additive). This crystal showed Hi-NagB is active as a hexamer.  Pm-NagB crystal was obtained using a similar method, but with 0.1 M Sodium cacodylate pH 6.5, 0.2 M Magnesium chloride, and 20% w/v Polyethylene glycol 1,000. The Pm-NagB structureshowed it was active as a dimer. They propose the dimer form of Pm-NagB as an evolutionary link between the monomer and hexamer forms of NagB.