Lv Changjiang, Zhao Chungui, Yang Suping, Qu Yinbo
Department of Bioengineering and Biotechnology, Huaqiao University, Xiamen 361021, China.
Wei Sheng Wu Xue Bao. 2012 Dec 4;52(12):1497-507.
To elucidate the arsenic metabolic pathway of purple nonsulfur bacteria (PNSB).
We investigated the distribution within their genomes, organization, composition, arrangement, core genes and coding proteins of arsenic gene clusters found in complete genome from 17 strains of PNSB by comparing the genomes analysis, and studied the arsenic metabolism in 3 members of PNSB under anaerobic conditions by UV-Vis and HPLC-ICP-MS.
Arsenate reduction and arsenite methylation pathways mediated by ars operon are the dominating arsenic metabolic processes. The arsenic gene clusters differ vastly in composition and arrangement. Some members of PNSB evolved two independently families of arsenate reduction genes (arsC). The cells of Rhodopseudomonas palustris CQV97, Rhodobacter azotoformans 134K20 and Rhodobacter capsulatus XJ-1 could reduce As (V) to As (III), whereas As (III) could not be transformed back to As (V). Higher concentration phosphate competitively inhibited arsenate toxicity to cells.
Our investigations shed light on the evolution and functional implications in arsenic gene clusters of PNSB, and support the notion that arsenate reduction and arsenite methylation appears to be the dominant process in PNSB.
阐明紫色非硫细菌（PNSB）的砷代谢途径。
通过比较基因组分析，研究了17株PNSB完整基因组中砷基因簇在其基因组内的分布、组织、组成、排列、核心基因和编码蛋白，并利用紫外可见光谱和高效液相色谱-电感耦合等离子体质谱法研究了3株PNSB在厌氧条件下的砷代谢。
由ars操纵子介导的砷酸盐还原和亚砷酸盐甲基化途径是主要的砷代谢过程。砷基因簇在组成和排列上差异很大。一些PNSB成员进化出了两个独立的砷酸盐还原基因（arsC）家族。沼泽红假单胞菌CQV97、固氮红杆菌134K20和荚膜红杆菌XJ-1的细胞可将As（V）还原为As（III），而As（III）不能再转化回As（V）。较高浓度的磷酸盐可竞争性抑制砷酸盐对细胞的毒性。
我们的研究揭示了PNSB砷基因簇的进化及其功能意义，并支持砷酸盐还原和亚砷酸盐甲基化似乎是PNSB主要过程的观点。
