Dipartimento di Biochimica e Biologia Molecolare, Università degli Studi di Bari, Bari, Italy.
J Appl Microbiol. 2009 Jan;106(1):338-49. doi: 10.1111/j.1365-2672.2008.04007.x. Epub 2008 Nov 28.
To investigate the surviving capability of Rhodobacter sphaeroides under phototrophic conditions in the presence of high cobalt concentration and its influence on the photosynthetic apparatus biosynthesis.
Cells from R. sphaeroides strain R26.1 were grown anaerobically in a medium containing 5.0 mmol l(-1) cobalt ions and in a control medium. Metal toxicity was investigated comparing the soluble proteome of Co(2+)-exposed cells and cells grown in control medium by two-dimensional gel electrophoretic analysis. Significant changes in the expression level were detected for 43 proteins, the majority (35) being up-regulated. The enzyme porphobilinogen deaminase (PBGD) was found down-regulated and its activity was investigated.
The up-regulated enzymes mainly belong to the general category of proteins and DNA degradation enzymes, suggesting that part of the catabolic reaction products can rescue bacterial growth in photosynthetically impaired cells. Furthermore, the down-regulation of PBGD strongly indicates that this key enzyme of the tetrapyrrole and bacteriochlorophyll synthesis is directly involved in the metabolic response.
Data and experiments show that the cobalt detrimental effect on the photosynthetic growth of R. sphaeroides is associated with an impaired expression and functioning of PBGD.
研究在高钴浓度存在的光养条件下球形红杆菌的存活能力及其对光合器官生物合成的影响。
从 R. sphaeroides 菌株 R26.1 中分离出的细胞在含有 5.0 mmol l(-1) 钴离子的培养基中和对照培养基中进行厌氧生长。通过二维凝胶电泳分析比较 Co(2+)-暴露细胞和在对照培养基中生长的细胞的可溶性蛋白质组，研究金属毒性。检测到 43 种蛋白质的表达水平发生显著变化，其中大多数（35 种）上调。发现酶卟胆原脱氨酶（PBGD）下调，并对其活性进行了研究。
上调的酶主要属于一般蛋白质和 DNA 降解酶类，表明部分分解代谢产物可以挽救光合受损细胞中的细菌生长。此外，PBGD 的下调强烈表明，该四吡咯和细菌叶绿素合成的关键酶直接参与了代谢反应。
数据和实验表明，钴对 R. sphaeroides 光合生长的有害影响与 PBGD 的表达和功能受损有关。
