Klotz M G, Alzerreca J, Norton J M
Department of Biology, University of Colorado, Denver 80217-3364, USA.
FEMS Microbiol Lett. 1997 May 1;150(1):65-73. doi: 10.1111/j.1574-6968.1997.tb10351.x.
The gene cluster encoding ammonia monooxygenase (AMO) in the chemolithotrophic soil bacterium Nitrosospira sp. NpAV was found to contain a third open reading frame, termed amoC, upstream of the genes amoA and amoB that encode the subunits of AMO. The amoC gene and its flanking regions were isolated and sequenced from a 4.4 kb EcoRI fragment that contains one of three copies of the ammonia monooxygenase gene cluster. The presence of this gene upstream of the other two amoA gene copies in Nitrosospira NpAV as well as upstream of amoA genes in the genomes of other ammonia oxidizing nitrifiers (strains in the genera Nitrosomonas, Nitrosopira, Nitrosolobus and Nitrosovibrio) was confirmed using genomic DNA, oligodeoxyribonucleotide primers and the PCR. The amoC gene in Nitrosospira sp. NpAV encodes a 270 amino acid polypeptide of approximately 36 kDa. Topological analysis of the predicted primary structure revealed 6 membrane spanning domains. The amoC gene was expressed in recombinant Escherichia coli from its indigenous promoter.
在化能自养土壤细菌嗜亚硝化螺菌属NpAV中，编码氨单加氧酶（AMO）的基因簇被发现包含第三个开放阅读框，称为amoC，位于编码AMO亚基的amoA和amoB基因上游。从一个4.4 kb的EcoRI片段中分离并测序了amoC基因及其侧翼区域，该片段包含氨单加氧酶基因簇三个拷贝中的一个。利用基因组DNA、寡脱氧核糖核苷酸引物和PCR，证实了该基因在嗜亚硝化螺菌NpAV中另外两个amoA基因拷贝上游以及其他氨氧化硝化菌（亚硝化单胞菌属、亚硝化螺菌属、亚硝化叶菌属和亚硝化弧菌属中的菌株）基因组中amoA基因上游均存在。嗜亚硝化螺菌属NpAV中的amoC基因编码一个约36 kDa的270个氨基酸的多肽。对预测的一级结构进行拓扑分析发现有6个跨膜结构域。amoC基因从其自身启动子在重组大肠杆菌中表达。
