Mejía-Ruíz H, Guzmán J, Moreno S, Soberón-Chávez G, Espín G
Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos.
Gene. 1997 Oct 15;199(1-2):271-7. doi: 10.1016/s0378-1119(97)00380-6.
A 2.8-kb DNA region, located immediately downstream of algD, contains the A. vinelandii alg8 and alg44 genes, whose sequences are highly homologous to those of the corresponding Pseudomonas aeruginosa genes. These genes occur on a transcript that does not include algD, and are transcribed from a promoter different from that transcribing algD; this is the fourth promoter described within the alginate biosynthetic gene cluster. alg8 and alg44 mutants were constructed and shown to be completely impaired in alginate production. Alg8 shares 28.20% identity and 38.09% similarity to Azorhizobium caulinodans NodC, a glycosyl transferase catalyzing the formation of beta-1,4 linkages. A topological model is predicted, which supports the idea of Alg8 being the polymerase responsible for alginate synthesis.
一个位于algD基因紧邻下游的2.8 kb DNA区域，包含了棕色固氮菌的alg8和alg44基因，其序列与铜绿假单胞菌相应基因的序列高度同源。这些基因位于一个不包含algD的转录本上，并且由一个与转录algD的启动子不同的启动子转录；这是藻酸盐生物合成基因簇中描述的第四个启动子。构建了alg8和alg44突变体，并证明它们在藻酸盐产生方面完全受损。Alg8与茎瘤固氮根瘤菌的NodC（一种催化β-1,4连接形成的糖基转移酶）具有28.20%的同一性和38.09%的相似性。预测了一个拓扑模型，该模型支持Alg8是负责藻酸盐合成的聚合酶这一观点。
