Glucosamine-6-phosphate N-acetyltransferase 1 (GNA1) produces GlcNAc-6-phosphate from GlcN-6-phosphate and acetyl coenzyme A. Early mercury-labelling experiments implicated a conserved cysteine in the reaction mechanism, whereas recent structural data appear to support a mechanism in which this cysteine plays no role. Here, two crystal structures of Caenorhabditis elegans GNA1 are reported, revealing an unusual covalent complex between this cysteine and the coenzyme A product. Mass-spectrometric and reduction studies showed that this inactive covalent complex can be reactivated through reduction, yet mutagenesis of the cysteine supports a previously reported bi-bi mechanism. The data unify the apparently contradictory earlier reports on the role of a cysteine in the GNA1 active site.
|Number of pages||11|
|Journal||Acta Crystallographica Section D: Biological Crystallography|
|Publication status||Published - 2012|
Dorfmueller, H. C., Fang, W., Rao, F. V., Blair, D. E., Attrill, H., & van Aalten, D. M. F. (2012). Structural and biochemical characterization of a trapped coenzyme a adduct of Caenorhabditis elegans glucosamine-6-phosphate N-acetyltransferase 1. Acta Crystallographica Section D: Biological Crystallography, 68(8), 1019-1029. https://doi.org/10.1107/S0907444912019592