Weston S A, Camble R, Colls J, Rosenbrock G, Taylor I, Egerton M, Tucker A D, Tunnicliffe A, Mistry A, Mancia F, de la Fortelle E, Irwin J, Bricogne G, Pauptit R A
Zeneca Pharmaceuticals, Macclesfield, UK.
Nat Struct Biol. 1998 Mar;5(3):213-21. doi: 10.1038/nsb0398-213.
N-myristoyl transferase (NMT) catalyzes the transfer of the fatty acid myristate from myristoyl-CoA to the N-terminal glycine of substrate proteins, and is found only in eukaryotic cells. The enzyme in this study is the 451 amino acid protein produced by Candida albicans, a yeast responsible for the majority of systemic infections in immuno-compromised humans. NMT activity is essential for vegetative growth, and the structure was determined in order to assist in the discovery of a selective inhibitor of NMT which could be developed as an anti-fungal drug. NMT has no sequence homology with other protein sequences and has a novel alpha/beta fold which shows internal two-fold symmetry, which may be a result of gene duplication. On one face of the protein there is a long, curved, relatively uncharged groove, at the center of which is a deep pocket. The pocket floor is negatively charged due to the vicinity of the C-terminal carboxylate and a nearby conserved glutamic acid residue, which separates the pocket from a cavity. These observations, considered alongside the positions of residues whose mutation affects substrate binding and activity, suggest that the groove and pocket are the sites of substrate binding and the floor of the pocket is the catalytic center.
N-肉豆蔻酰转移酶（NMT）催化肉豆蔻酸从肉豆蔻酰辅酶A转移至底物蛋白的N端甘氨酸，且仅存在于真核细胞中。本研究中的该酶是由白色念珠菌产生的含451个氨基酸的蛋白质，白色念珠菌是一种酵母，可导致免疫功能低下的人类发生大多数全身性感染。NMT活性对于营养生长至关重要，确定其结构是为了帮助发现一种可作为抗真菌药物开发的NMT选择性抑制剂。NMT与其他蛋白质序列无序列同源性，具有一种新颖的α/β折叠，呈现内部二重对称，这可能是基因复制的结果。在该蛋白质的一个面上有一条长的、弯曲的、相对不带电的凹槽，其中心是一个深口袋。由于C端羧酸盐和附近一个保守的谷氨酸残基的存在，口袋底部带负电，这将口袋与一个腔分隔开。这些观察结果，结合那些其突变影响底物结合和活性的残基的位置来看，表明凹槽和口袋是底物结合位点，口袋底部是催化中心。
