Tiburtius A, de Luca N G, Hussain H, Johnston A W
School of Biological Sciences, University of East Anglia, Norwich, UK.
Microbiology (Reading). 1996 Sep;142 ( Pt 9):2621-9. doi: 10.1099/00221287-142-9-2621.
Some mutants of Agrobacterium radiobacter, defective in exopolysaccharide synthesis, were phenotypically complemented by two different regions of cloned chromosomal DNA. One of these had been shown to contain a gene termed ros, a novel class of transcriptional regulator. The other contains a gene termed exoY which encodes a glycosyltransferase that is involved in one of the early steps in exopolysaccharide synthesis. Mutations in ros reduced the expression of exoY and a model to account for the complementation of certain exo alleles by both ros and exoY is presented. TnphoA insertions into exoY which expressed alkaline phosphatase activity were isolated and mapped, confirming the membrane location of the exoY gene product. Some of these mutations were dominant, causing merodiploids to be non-mucoid. exoY is linked to two genes, one encoding an omega-aminotransferase and the other encoding an aldehyde dehydrogenase.
一些在胞外多糖合成方面存在缺陷的放射形土壤杆菌突变体，在表型上被克隆染色体DNA的两个不同区域互补。其中一个区域已被证明含有一个名为ros的基因，这是一类新型的转录调节因子。另一个区域含有一个名为exoY的基因，它编码一种糖基转移酶，该酶参与胞外多糖合成的早期步骤之一。ros突变会降低exoY的表达，并提出了一个解释ros和exoY对某些exo等位基因进行互补的模型。分离并定位了插入exoY且表达碱性磷酸酶活性的TnphoA插入片段，证实了exoY基因产物的膜定位。其中一些突变是显性的，导致部分二倍体无黏液状。exoY与两个基因相连，一个编码ω-氨基转移酶，另一个编码醛脱氢酶。
