Kamath A V, Vaaler G L, Snell E E
Department of Microbiology, University of Texas, Austin 78712.
J Biol Chem. 1991 May 25;266(15):9432-7.
The hdc genes encoding the inducible pyridoxal-P-dependent histidine decarboxylase (HisDCase) of Klebsiella planticola and Enterobacter aerogenes were isolated, sequenced, and expressed in Escherichia coli under control of the lac promoter, and the overproduced enzymes were purified to homogeneity from the recombinant host. Formation of inclusion bodies during synthesis of the E. aerogenes enzyme was avoided by cooling the culture and inducing at 25 degrees C. The cloned enzymes were produced in amounts three to four times those present in the fully induced native hosts and were identical in properties to those isolated earlier (Guirard, B. M., and Snell, E. E. (1987) J. Bacteriol. 169, 3963-3968). The two enzymes showed 85% sequence identity and also showed 80% sequence identity with the previously sequenced (Vaaler, G. L., Brasch, M. A., and Snell, E. E. (1986) J. Biol. Chem. 261, 11010-11014) HisDCase of Morganella morganii. Nevertheless, antibodies to the M. morganii HisDCase do not cross-react with these enzymes suggesting that the regions of amino acid variations are located on the outer surface of the proteins. All three HisDCases are the same length (377 amino acid residues); encoded N-terminal methionine was completely removed in each case. These closely related pyridoxal-P enzymes show no sequence homology with the pyruvoyl-dependent HisDCases of Gram-positive bacteria.
分离、测序了编码植物源克雷伯氏菌和产气肠杆菌中可诱导的磷酸吡哆醛依赖性组氨酸脱羧酶（HisDCase）的hdc基因，并在乳糖启动子的控制下在大肠杆菌中表达，从重组宿主中纯化过量产生的酶至均一性。通过冷却培养物并在25℃诱导，避免了产气肠杆菌酶合成过程中包涵体的形成。克隆酶的产量是完全诱导的天然宿主中酶产量的三到四倍，并且其性质与早期分离的酶相同（吉拉德，B.M.，和斯内尔，E.E.（1987年）《细菌学杂志》169卷，3963 - 3968页）。这两种酶显示出85%的序列同一性，并且与先前测序的摩根氏摩根菌HisDCase（瓦勒，G.L.，布拉施，M.A.，和斯内尔，E.E.（1986年）《生物化学杂志》261卷，11010 - 11014页）也显示出80%的序列同一性。然而，针对摩根氏摩根菌HisDCase的抗体与这些酶不发生交叉反应，这表明氨基酸变异区域位于蛋白质的外表面。所有三种HisDCase长度相同（377个氨基酸残基）；每种情况下编码的N端甲硫氨酸都被完全去除。这些密切相关的磷酸吡哆醛酶与革兰氏阳性菌中依赖于丙酮酸的HisDCase没有序列同源性。
