Newton G L, Fahey R C, Cohen G, Aharonowitz Y
Department of Chemistry, University of California, San Diego, La Jolla 92093.
J Bacteriol. 1993 May;175(9):2734-42. doi: 10.1128/jb.175.9.2734-2742.1993.
The intracellular low-molecular-weight thiols present in five gram-positive Streptomyces species and one Flavobacterium species were analyzed by high-performance liquid chromatography after fluorescence labeling with monobromobimane. Bacteria were chosen to include penicillin and cephalosporin beta-lactam producers and nonproducers. No significant amount of glutathione was found in any of the streptomycetes. Major intracellular thiols in all strains examined were cysteine, coenzyme A, sulfide, thiosulfate, and an unknown thiol designated U17. Those streptomycetes that make beta-lactam antibiotics also produce significant amounts of delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine (ACV), a key intermediate in their biosynthesis. In Streptomyces clavuligerus, a potent producer of beta-lactams, the level of ACV was low during the early phase of growth and increased rapidly toward the end of exponential growth, paralleling that of antibiotic production. These and other observations indicate that ACV does not function as a protective thiol in streptomycetes. U17 may have this role since it was the major thiol in all streptomycetes and appeared to occur at levels about 10-fold higher than those of the other thiols measured, including ACV. Purification and amino acid analysis of U17 indicated that it contains cysteine and an unusual amine that is not one of the common amino acids. This thiol is identical to an unknown thiol found previously in Micrococcus roseus and Streptomyces griseus. A high level of ergothioneine was found in Streptomyces lactamdurans, and several unidentified thiols were detected in this and other streptomycetes.
用单溴代联苯胺进行荧光标记后，通过高效液相色谱法分析了5种革兰氏阳性链霉菌属物种和1种黄杆菌属物种中的细胞内低分子量硫醇。选择的细菌包括青霉素和头孢菌素β-内酰胺产生菌及非产生菌。在任何链霉菌中均未发现大量的谷胱甘肽。在所检测的所有菌株中，主要的细胞内硫醇为半胱氨酸、辅酶A、硫化物、硫代硫酸盐以及一种名为U17的未知硫醇。那些产生β-内酰胺抗生素的链霉菌也会产生大量的δ-（L-α-氨基己二酰基）-L-半胱氨酰-D-缬氨酸（ACV），这是其生物合成中的关键中间体。在强效β-内酰胺产生菌克拉维链霉菌中，ACV的水平在生长早期较低，在指数生长末期迅速增加，与抗生素产生情况平行。这些以及其他观察结果表明，ACV在链霉菌中并非作为保护性硫醇发挥作用。U17可能具有这一作用，因为它是所有链霉菌中的主要硫醇，其含量似乎比所测定的其他硫醇（包括ACV）高出约10倍。U17的纯化和氨基酸分析表明，它含有半胱氨酸和一种不常见的胺，该胺不是常见氨基酸之一。这种硫醇与先前在玫瑰微球菌和灰色链霉菌中发现的一种未知硫醇相同。在耐内酰胺链霉菌中发现了高水平的麦角硫因，在该菌及其他链霉菌中还检测到了几种未鉴定的硫醇。
