The quaternary structure of Escherichia coli N-acetylneuraminate lyase is essential for functional expression.
As part of a general study into the impact of quaternary structure on enzyme function, a library of 31 point mutations were engineered at the dimer-dimer interface of the homotetrameric (beta/alpha)(8)-barrel protein, N-acetylneuraminate lyase (NAL, EC 4.1.3.3). Disruption of the interface generated either soluble tetramers or putative dimers that were absolutely insoluble and inactive. Intriguingly, the soluble tetramers were found to have widely varying k(cat) values, hinting at a role for the interface in catalysis. Leucine 171 was identified as essential to interface integrity. We conclude that the dimer-dimer interface of NAL is intolerant to mutation and essential for functional expression.
Devenish
Sean R A
SR
University of Canterbury, Christchurch, New Zealand. sean.devenish@canterbury.ac.nz
Gerrard
Juliet A
JA
D004926:Escherichia coli / Q000201:enzymology*; D007930:Leucine / Q000737:chemistry / Q000235:genetics; D007652:Oxo-Acid-Lyases / Q000096:biosynthesis* / Q000737:chemistry* / Q000235:genetics; D017354:Point Mutation; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary / Q000235:genetics
D007652:Oxo-Acid-Lyases; C018728:N-acetylneuraminate lyase; D007930:Leucine