Fluorescence studies of nucleotide binding processes of AnmK (1,6-Anhydro-N-acetylmuramic acid kinase)

Abstract

1,6-Anhydro-N-acetylmuramic acid kinase (AnmK) is a homodimeric enzyme that can convert 1,6-Anhydro-N-acetylmuramic acid into N-acetylglucosamine-6-phosphate by consuming one molecule of ATP in murein recycling in Gram-negative bacteria. Structural data indicate that each subunit of AnmK is comprised of two domains that are separated by a deep active site cleft, which bears similarity to the ATPase core of proteins belonging to the hexokinase-hsp70-actin superfamily of proteins. These data also show that binding of ATP analogue changes the structure of AnmK. Our data suggest that AnmK is an allosteric enzyme and ATP binding follows Monod-Wyman-Changeux model (MWC). The apo-AnmK has two different conformations, one is more open (R state) and the other one is closed (T state). Binding of ATP to AnmK stabilizes the more open (R state) and makes AnmK prone to bind to anhMurNAc sugar.