A bacterial cytokine

Viable cells of Micrococcus luteus secrete a factor, which promotes the resuscitation and growth of dormant, nongrowing cells of the same organism. The resuscitation-promoting factor (Rpf) is a protein, which has been purified to homogeneity. In picomolar concentrations, it increases the viable cell count of dormant M. luteus cultures at least 100-fold and can also stimulate the growth of viable cells. Rpf also stimulates the growth of several other high G+C Gram-positive organisms, including Mycobacterium avium, Mycobacterium bovis (BCG), Mycobacterium kansasii, Mycobacterium smegmatis, and Mycobacterium tuberculosis. Similar genes are widely distributed among high G+C Gram-positive bacteria; genome sequencing has uncovered examples in Mycobacterium leprae and Mb. tuberculosis and others have been detected by hybridization in Mb. smegmatis, Corynebacterium glutamicum, and Streptomyces spp. The mycobacterial gene products may provide different targets for the detection and control of these important pathogens. This report is thus a description of a proteinaceous autocrine or paracrine bacterial growth factor or cytokine.

藤黄微球菌（Micrococcus luteus）的活细胞可分泌一种因子，能够促进该菌自身休眠且处于静止增殖状态的细胞复苏与生长。复苏促进因子（resuscitation-promoting factor，Rpf）是一种已被纯化至均一状态的蛋白质。在皮摩尔浓度下，该因子可使休眠的藤黄微球菌培养物的活细胞数量至少提升100倍，同时还可刺激活细胞的增殖。Rpf还能促进多种其他高G+C革兰氏阳性菌（high G+C Gram-positive organisms）的生长，涵盖鸟分枝杆菌（Mycobacterium avium）、牛分枝杆菌（Mycobacterium bovis，BCG）、堪萨斯分枝杆菌（Mycobacterium kansasii）、耻垢分枝杆菌（Mycobacterium smegmatis）以及结核分枝杆菌（Mycobacterium tuberculosis）。此类同源基因广泛分布于高G+C革兰氏阳性菌中；基因组测序已在麻风分枝杆菌（Mycobacterium leprae）与结核分枝杆菌中发现了该类基因，此外通过杂交技术还可在耻垢分枝杆菌、谷氨酸棒杆菌（Corynebacterium glutamicum）以及链霉菌属（Streptomyces spp.）中检测到相关基因。分枝杆菌来源的该基因编码产物，可为这类重要致病菌的检测与防控提供差异化靶点。因此，本研究报道的是一种具有蛋白质特性的细菌自分泌或旁分泌生长因子，亦可归类为细胞因子。