Carminatti C A, Oliveira I L, Recouvreux D O S, Antônio R V, Porto L M
Departamento de Engenharia Química e Engenharia de Alimentos, Universidade Federal de Santa Catarina, Florianópolis, SC, Brasil.
Genet Mol Res. 2008 Sep 16;7(3):830-8. doi: 10.4238/vol7-3x-meeting001.
Tryptophan is an aromatic amino acid used for protein synthesis and cellular growth. Chromobacterium violaceum ATCC 12472 uses two tryptophan molecules to synthesize violacein, a secondary metabolite of pharmacological interest. The genome analysis of this bacterium revealed that the genes trpA-F and pabA-B encode the enzymes of the tryptophan pathway in which the first reaction is the conversion of chorismate to anthranilate by anthranilate synthase (AS), an enzyme complex. In the present study, the organization and structure of AS protein subunits from C. violaceum were analyzed using bioinformatics tools available on the Web. We showed by calculating molecular masses that AS in C. violaceum is composed of alpha (TrpE) and beta (PabA) subunits. This is in agreement with values determined experimentally. Catalytic and regulatory sites of the AS subunits were identified. The TrpE and PabA subunits contribute to the catalytic site while the TrpE subunit is involved in the allosteric site. Protein models for the TrpE and PabA subunits were built by restraint-based homology modeling using AS enzyme, chains A and B, from Salmonella typhimurium (PDB ID 1I1Q).
色氨酸是一种用于蛋白质合成和细胞生长的芳香族氨基酸。紫色色杆菌ATCC 12472利用两个色氨酸分子合成了紫菌素，一种具有药理学意义的次级代谢产物。对该细菌的基因组分析表明，trpA - F和pabA - B基因编码色氨酸途径中的酶，其中第一个反应是由邻氨基苯甲酸合酶（AS）（一种酶复合物）将分支酸转化为邻氨基苯甲酸。在本研究中，利用网络上可用的生物信息学工具分析了紫色色杆菌AS蛋白亚基的组织和结构。我们通过计算分子量表明，紫色色杆菌中的AS由α（TrpE）和β（PabA）亚基组成。这与实验确定的值一致。鉴定了AS亚基的催化和调节位点。TrpE和PabA亚基对催化位点有贡献，而TrpE亚基参与变构位点。使用来自鼠伤寒沙门氏菌（PDB ID 1I1Q）的AS酶A链和B链，通过基于约束的同源建模构建了TrpE和PabA亚基的蛋白质模型。
