IDENTIFICATION OF AN OPERON INVOLVED IN SULFOLIPID BIOSYNTHESIS IN RHODOBACTER-SPHAEROIDES
IDENTIFICATION OF AN OPERON INVOLVED IN SULFOLIPID BIOSYNTHESIS IN RHODOBACTER-SPHAEROIDES
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DOI：
10.1128/jb.174.20.6479-6487.1992
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发表时间：
1992-10-01
影响因子：
3.2
通讯作者：
SOMERVILLE, CR
中科院分区：
文献类型：
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作者：
BENNING, C;SOMERVILLE, CR
通过脂质提取物的薄层层析直接筛选诱变细胞株的极性脂质组成，分离到两个新的硫脂积累缺陷型球形红细菌突变株。鉴定了一个基因组克隆，其补充了这两个品系中的突变，但不是先前描述的硫脂质缺陷sqdA突变体。克隆的相关区域的序列分析揭示了三个串联开放阅读框，命名为sqdB、ORF 2和sqdC。其中一个突变体由sqdB基因互补，另一个由sqdC基因互补。sqdB的插入失活也使sqdC失活，表明sqdB和sqdC是共转录的。由sqdB基因编码的46-kDa推定蛋白的N-末端区域与来自各种生物体的UDP-葡萄糖差向异构酶表现出轻微的同源性。由ORF 2编码的30-kDa推定的蛋白质显示出非常惊人的同源性，兔肌糖原，UDP-葡萄糖利用，autoglycosylating糖基转移酶。由sqdC基因编码的26-kDa推定蛋白质与任何已知功能的蛋白质都不同源。
Two new mutants of Rhodobacter sphaeroides deficient in sulfolipid accumulation were isolated by directly screening mutagenized cell tines for polar lipid composition by thin-layer chromatography of lipid extracts. A genomic clone which complemented the mutations in these two lines, but not the previously described sulfolipid-deficient sqdA mutant, was identified. Sequence analysis of the relevant region of the clone revealed three, in tandem open reading frames, designated sqdB, ORF2, and sqdC. One of the mutants was complemented by the sqdB gene, and the other was complemented by the sqdC gene. Insertional inactivation of sqdB also inactivated sqdC, indicating that sqdB and sqdC are cotranscribed. The N-terminal region of the 46-kDa putative protein encoded by the sqdB gene showed slight homology to UDP-glucose epimerase from various organisms. The 30-kDa putative protein encoded by ORF2 showed very striking homology to rabbit muscle glycogenin, a UDP-glucose utilizing, autoglycosylating glycosyltransferase. The 26-kDa putative protein encoded by the sqdC gene was not homologous to any protein of known function.