@article {3743,
	title = {A dimer between monomers and hexamers-Oligomeric variations in glucosamine-6-phosphate deaminase family.},
	journal = {PLoS One},
	volume = {18},
	year = {2023},
	month = {2023},
	pages = {e0271654},
	abstract = {<p>In bacteria that live in hosts whose terminal sugar is a sialic acid, Glucosamine-6-phosphate deaminase (NagB) catalyzes the last step in converting sialic acid into Fructose-6-phosphate. These bacteria then use the Fructose-6-phosphate as an energy source. The enzyme NagB exists as a hexamer in Gram-negative bacteria and is allosterically regulated. In Gram-positive bacteria, it exists as a monomer and lacks allosteric regulation. Our identification of a dimeric Gram-negative bacterial NagB motivated us to characterize the structural basis of two closely related oligomeric forms. We report here the crystal structures of NagB from two Gram-negative pathogens, Haemophilus influenzae (Hi) and Pasturella multocida (Pm). The Hi-NagB is active as a hexamer, while Pm-NagB is active as a dimer. Both Hi-NagB and Pm-NagB contain the C-terminal helix implicated as essential for hexamer formation. The hexamer is described as a dimer of trimers. In the Pm-NagB dimer, the dimeric interface is conserved. The conservation of the dimer interface suggests that the three possible oligomeric forms of NagB are a monomer, a dimer, and a trimer of dimers. Computational modeling and MD simulations indicate that the residues at the trimeric interface have less stabilizing energy of oligomer formation than those in the dimer interface. We propose that Pm-NagB is the evolutionary link between the monomer and the hexamer forms.</p>
},
	keywords = {Aldose-Ketose Isomerases, Bacterial Proteins, Haemophilus influenzae, N-Acetylneuraminic Acid, Pasteurella multocida, Polymers},
	issn = {1932-6203},
	doi = {10.1371/journal.pone.0271654},
	author = {Srinivasachari, Sathya and Tiwari, Vikas R and Kharbanda, Tripti and Sowdamini, Ramanathan and Subramanian, Ramaswamy}
}
@article {1597,
	title = {Crystal structures and kinetics of N-acetylneuraminate lyase from Fusobacterium nucleatum.},
	journal = {Acta Crystallogr F Struct Biol Commun},
	volume = {74},
	year = {2018},
	month = {2018 Nov 01},
	pages = {725-732},
	abstract = {<p>N-Acetyl-D-neuraminic acid lyase (NanA) catalyzes the breakdown of sialic acid (Neu5Ac) to N-acetyl-D-mannosamine (ManNAc) and pyruvate. NanA plays a key role in Neu5Ac catabolism in many pathogenic and bacterial commensals where sialic acid is available as a carbon and nitrogen source. Several pathogens or commensals decorate their surfaces with sialic acids as a strategy to escape host innate immunity. Catabolism of sialic acid is key to a range of host-pathogen interactions. In this study, atomic resolution structures of NanA from Fusobacterium nucleatum (FnNanA) in ligand-free and ligand-bound forms are reported at 2.32 and 1.76 {\r A} resolution, respectively. F. nucleatum is a Gram-negative pathogen that causes gingival and periodontal diseases in human hosts. Like other bacterial N-acetylneuraminate lyases, FnNanA also shares the triosephosphate isomerase (TIM)-barrel fold. As observed in other homologous enzymes, FnNanA forms a tetramer. In order to characterize the structure-function relationship, the steady-state kinetic parameters of the enzyme are also reported.</p>
},
	keywords = {Bacterial Proteins, Crystallography, X-Ray, Fusobacterium nucleatum, Hydrogen Bonding, Models, Molecular, N-Acetylneuraminic Acid, Oxo-Acid-Lyases, Protein Conformation, Protein Folding, Pyruvic Acid, Schiff Bases, Sequence Alignment, Tyrosine},
	issn = {2053-230X},
	doi = {10.1107/S2053230X18012992},
	author = {Kumar, Jay Prakash and Rao, Harshvardhan and Nayak, Vinod and Ramaswamy, S}
}
