The pssA gene encodes UDP-glucose:: Polyprenyl phosphate-glucosyl phosphotransferase initiating biosynthesis of Rhizobium leguminosarum exopolysaccharide
The pssA gene encodes UDP-glucose:: Polyprenyl phosphate-glucosyl phosphotransferase initiating biosynthesis of Rhizobium leguminosarum exopolysaccharide
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DOI：
10.1134/s1068162007010177
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发表时间：
2007-02-01
影响因子：
1
通讯作者：
Shibaev, V. N.
中科院分区：
文献类型：
--
作者：
Ksenzenko, V. N.;Ivashina, T. V.;Shibaev, V. N.
共生固氮菌豆科根瘤菌豌豆VF39分泌酸性杂多糖，其生物合成涉及聚戊烯基二磷酸八糖的形成阶段，其碳水化合物片段对应于重复的聚合物单元。对PSSA基因产物的氨基酸分析表明，它与细菌聚异戊二烯基磷酸己糖1-磷酸转移酶同源，该转移酶催化聚戊烯基磷酸和己糖1-磷酸之间形成磷酸二酯键，其供体为核苷酸。免疫印迹表明，根瘤菌细胞合成了一种相对分子质量为25 kDa的蛋白质，这意味着第二个起始密码子的开放阅读框发生了翻译，随后进行了蛋白质加工。结果表明，PSSA是一种完整的膜结合蛋白，参与了葡萄糖1-磷酸从UDP-葡萄糖向聚戊烯基磷酸转移形成聚戊烯基二磷酸葡萄糖的过程。这些结果表明，PSSA基因编码UDP-葡萄糖：聚戊烯基磷酸-葡萄糖磷酸转移酶。
Symbiotic nitrogen-fixing bacteria Rhizobium leguminosarum bv. viciae VF39 secrete an acidic heteropolysaccharide, the biosynthesis of which involves the stage of polyprenyl diphosphate octasaccharide formation with its carbohydrate fragment corresponding to the repeating polymer unit. The amino acid analysis of the product of the pssA gene, we have earlier identified, showed its homology to bacterial polyisoprenyl phosphate hexose 1-phosphate transferases catalyzing the formation of phosphodiester bonds between polyprenyl phosphates and hexose 1-phosphates, whose donors are nucleotide sugars. The immunoblotting demonstrated that Rhizobium cells synthesize a protein with a molecular mass of 25 kDa, which implies the translation of the open reading frame occurring from the second initiating codon followed by the protein processing. It was shown that PssA is an integral membrane-bound protein involved in glucose 1-phosphate transfer from UDP-glucose to polyprenyl phosphate to form polyprenyl diphosphate glucose. These results suggest that the pssA gene encodes UDP-glucose:polyprenyl phosphate-glucosyl phosphotransferase.