Suzuki K, Wakao N, Kimura T, Sakka K, Ohmiya K
Laboratory of Applied Microbiology, School of Bioresources, Mie University, Tsu, Japan.
Appl Environ Microbiol. 1998 Feb;64(2):411-8. doi: 10.1128/AEM.64.2.411-418.1998.
The arsenic resistance (ars) operon from plasmid pKW301 of Acidiphilium multivorum AIU 301 was cloned and sequenced. This DNA sequence contains five genes in the following order: arsR, arsD, arsA, arsB, arsC. The predicted amino acid sequences of all of the gene products are homologous to the amino acid sequences of the ars gene products of Escherichia coli plasmid R773 and IncN plasmid R46. The ars operon cloned from A. multivorum conferred resistance to arsenate and arsenite on E. coli. Expression of the ars genes with the bacteriophage T7 RNA polymerase-promoter system allowed E. coli to overexpress ArsD, ArsA, and ArsC but not ArsR or ArsB. The apparent molecular weights of ArsD, ArsA, and ArsC were 13,000, 64,000, and 16,000, respectively. A primer extension analysis showed that the ars mRNA started at a position 19 nucleotides upstream from the arsR ATG in E. coli. Although the arsR gene of A. multivorum AIU 301 encodes a polypeptide of 84 amino acids that is smaller and less homologous than any of the other ArsR proteins, inactivation of the arsR gene resulted in constitutive expression of the ars genes, suggesting that ArsR of pKW301 controls the expression of this operon.
嗜酸氧化亚铁硫杆菌AIU 301质粒pKW301上的抗砷（ars）操纵子被克隆并测序。该DNA序列包含五个基因，顺序如下：arsR、arsD、arsA、arsB、arsC。所有基因产物的预测氨基酸序列与大肠杆菌质粒R773和IncN质粒R46的ars基因产物的氨基酸序列同源。从嗜酸氧化亚铁硫杆菌克隆的ars操纵子赋予大肠杆菌对砷酸盐和亚砷酸盐的抗性。利用噬菌体T7 RNA聚合酶启动子系统表达ars基因，使大肠杆菌能够过量表达ArsD、ArsA和ArsC，但不能过量表达ArsR或ArsB。ArsD、ArsA和ArsC的表观分子量分别为13,000、64,000和16,000。引物延伸分析表明，ars mRNA起始于大肠杆菌中arsR ATG上游19个核苷酸的位置。尽管嗜酸氧化亚铁硫杆菌AIU 301的arsR基因编码一种由84个氨基酸组成的多肽，该多肽比任何其他ArsR蛋白都小且同源性更低，但arsR基因的失活导致ars基因的组成型表达，这表明pKW301的ArsR控制该操纵子的表达。
