Ai Chenbing, Liang Yuting, Miao Bo, Chen Miao, Zeng Weimin, Qiu Guanzhou
School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, Hunan, China.
Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, 410083, China.
Curr Microbiol. 2018 Jul;75(7):818-826. doi: 10.1007/s00284-018-1453-9. Epub 2018 Feb 20.
Iron-oxidizing Acidithiobacillus spp. are applied worldwide in biomining industry to extract metals from sulfide minerals. They derive energy for survival through Fe oxidation and generate Fe for the dissolution of sulfide minerals. However, molecular mechanisms of their iron oxidation still remain elusive. A novel two-cytochrome-encoding gene cluster (named tce gene cluster) encoding a high-molecular-weight cytochrome c (AFE_1428) and a c-type cytochrome c (AFE_1429) in A. ferrooxidans ATCC 23270 was first identified in this study. Bioinformatic analysis together with transcriptional study showed that AFE_1428 and AFE_1429 were the corresponding paralog of Cyc2 (AFE_3153) and Cyc1 (AFE_3152) which were encoded by the extensively studied rus operon and had been proven involving in ferrous iron oxidation. Both AFE_1428 and AFE_1429 contained signal peptide and the classic heme-binding motif(s) as their corresponding paralog. The modeled structure of AFE_1429 showed high resemblance to Cyc1. AFE_1428 and AFE_1429 were preferentially transcribed as their corresponding paralogs in the presence of ferrous iron as sole energy source as compared with sulfur. The tce gene cluster is highly conserved in the genomes of four phylogenetic-related A. ferrooxidans strains that were originally isolated from different sites separated with huge geographical distance, which further implies the importance of this gene cluster. Collectively, AFE_1428 and AFE_1429 involve in Fe oxidation like their corresponding paralog by integrating with the metalloproteins encoded by rus operon. This study provides novel insights into the Fe oxidation mechanism in Fe-oxidizing A. ferrooxidans ssp.
铁氧化嗜酸氧化硫杆菌属在全球生物采矿行业中被用于从硫化物矿物中提取金属。它们通过铁氧化获取生存能量，并产生铁用于硫化物矿物的溶解。然而，其铁氧化的分子机制仍不清楚。本研究首次在氧化亚铁硫杆菌ATCC 23270中鉴定出一个新的双细胞色素编码基因簇（命名为tce基因簇），该基因簇编码一个高分子量细胞色素c（AFE_1428）和一个c型细胞色素c（AFE_1429）。生物信息学分析和转录研究表明，AFE_1428和AFE_1429分别是Cyc2（AFE_3153）和Cyc1（AFE_3152）的对应旁系同源物，Cyc2和Cyc1由广泛研究的rus操纵子编码，并且已被证明参与亚铁氧化。AFE_1428和AFE_1429都含有信号肽和与其对应旁系同源物相同的经典血红素结合基序。AFE_1429的模拟结构与Cyc1高度相似。与硫相比，在以亚铁作为唯一能源的情况下，AFE_1428和AFE_1429与其对应旁系同源物一样优先转录。tce基因簇在最初从地理距离遥远的不同地点分离的四种系统发育相关的氧化亚铁硫杆菌菌株的基因组中高度保守，这进一步暗示了该基因簇的重要性。总体而言，AFE_1428和AFE_1429与其对应旁系同源物一样，通过与rus操纵子编码的金属蛋白整合参与铁氧化。本研究为铁氧化嗜酸氧化硫杆菌亚种的铁氧化机制提供了新的见解。
