Kobayashi H, Takami H, Hirayama H, Kobata K, Usami R, Horikoshi K
Deep-Sea Microorganisms Research Group, Japan Marine Science and Technology Center, Yokosuka 237-0061, Japan.
J Bacteriol. 1999 Aug;181(15):4493-8. doi: 10.1128/JB.181.15.4493-4498.1999.
We isolated a toluene-sensitive mutant, named mutant No. 32, which showed unchanged antibiotic resistance levels, from toluene-tolerant Pseudomonas putida IH-2000 by transposon mutagenesis with Tn5. The gene disrupted by insertion of Tn5 was identified as cyoC, which is one of the subunits of cytochrome o. The membrane protein, phospholipid, and lipopolysaccharide (LPS) of IH-2000 and that of mutant No. 32 were examined and compared. Some of the outer membrane proteins showed a decrease in mutant No. 32. The fatty acid components of LPS were found to be dodecanoic acid, 2-hydroxydodecanoic acid, 3-hydroxydodecanoic acid, and 3-hydroxydecanoic acid in both IH-2000 and No. 32; however, the relative proportions of these components differed in the two strains. Furthermore, cell surface hydrophobicity was increased in No. 32. These data suggest that mutation of cyoC caused the decrease in outer membrane proteins and the changing fatty acid composition of LPS. These changes in the outer membrane would cause an increase in cell surface hydrophobicity, and mutant No. 32 is considered to be sensitive to toluene.
我们通过用Tn5进行转座子诱变，从耐甲苯的恶臭假单胞菌IH-2000中分离出了一个对甲苯敏感的突变体，命名为32号突变体，其抗生素抗性水平未发生变化。被Tn5插入破坏的基因被鉴定为cyoC，它是细胞色素o的亚基之一。对IH-2000和32号突变体的膜蛋白、磷脂和脂多糖（LPS）进行了检测和比较。32号突变体中的一些外膜蛋白有所减少。在IH-2000和32号突变体中，LPS的脂肪酸成分均为十二烷酸、2-羟基十二烷酸、3-羟基十二烷酸和3-羟基癸酸；然而，这两种菌株中这些成分的相对比例有所不同。此外，32号突变体的细胞表面疏水性增加。这些数据表明，cyoC的突变导致了外膜蛋白的减少以及LPS脂肪酸组成的变化。外膜的这些变化会导致细胞表面疏水性增加，并且32号突变体被认为对甲苯敏感。
