Chen A, Kroon P A, Poulter C D
Department of Chemistry, University of Utah, Salt Lake City 84112.
Protein Sci. 1994 Apr;3(4):600-7. doi: 10.1002/pro.5560030408.
Isoprenyl diphosphate synthases are ubiquitous enzymes that catalyze the basic chain-elongation reaction in the isoprene biosynthetic pathway. Pairwise sequence comparisons were made for 6 farnesyl diphosphate synthases, 6 geranylgeranyl diphosphate synthases, and a hexaprenyl diphosphate synthase. Five regions with highly conserved residues, two of which contain aspartate-rich DDXX(XX)D motifs found in many prenyltransferases, were identified. A consensus secondary structure for the group, consisting mostly of alpha-helices, was predicted for the multiply aligned sequences from amino acid compositions, computer assignments of local structure, and hydropathy indices. Progressive sequence alignments suggest that the 13 isoprenyl diphosphate synthases evolved from a common ancestor into 3 distinct clusters. The most distant separation is between yeast hexaprenyl diphosphate synthetase and the other enzymes. Except for the chromoplastic geranylgeranyl diphosphate synthase from Capsicum annuum, the remaining farnesyl and geranylgeranyl diphosphate synthases segregate into prokaryotic/archaebacterial and eukaryotic families.
异戊二烯基二磷酸合酶是普遍存在的酶，催化异戊二烯生物合成途径中的基本链延长反应。对6种法呢基二磷酸合酶、6种香叶基香叶基二磷酸合酶和1种六异戊二烯基二磷酸合酶进行了两两序列比较。鉴定出5个具有高度保守残基的区域，其中两个区域含有许多异戊二烯基转移酶中发现的富含天冬氨酸的DDXX(XX)D基序。根据氨基酸组成、局部结构的计算机分配和亲水性指数，对多重比对序列预测了该组的共有二级结构，该结构主要由α螺旋组成。渐进序列比对表明，13种异戊二烯基二磷酸合酶从一个共同祖先进化为3个不同的簇。距离最远的是酵母六异戊二烯基二磷酸合酶与其他酶之间。除了来自辣椒的质体香叶基香叶基二磷酸合酶外，其余的法呢基和香叶基香叶基二磷酸合酶分为原核生物/古细菌和真核生物家族。
