Ridge Justin P, Lin Marianne, Larsen Eloise I, Fegan Mark, McEwan Alastair G, Sly Lindsay I
Centre for Bacterial Diversity and Identification, University of Queensland, St. Lucia, Qld 4072, Australia.
Environ Microbiol. 2007 Apr;9(4):944-53. doi: 10.1111/j.1462-2920.2006.01216.x.
Pedomicrobium sp. ACM 3067 is a budding-hyphal bacterium belonging to the alpha-Proteobacteria which is able to oxidize soluble Mn2+ to insoluble manganese oxide. A cosmid, from a whole-genome library, containing the putative genes responsible for manganese oxidation was identified and a primer-walking approach yielded 4350 bp of novel sequence. Analysis of this sequence showed the presence of a predicted three-gene operon, moxCBA. The moxA gene product showed homology to multicopper oxidases (MCOs) and contained the characteristic four copper-binding motifs (A, B, C and D) common to MCOs. An insertion mutation of moxA showed that this gene was essential for both manganese oxidation and laccase-like activity. The moxB gene product showed homology to a family of outer membrane proteins which are essential for Type I secretion in Gram-negative bacteria. moxBA has not been observed in other manganese-oxidizing bacteria but homologues were identified in the genomes of several bacteria including Sinorhizobium meliloti 1021 and Agrobacterium tumefaciens C58. These results suggest that moxBA and its homologues constitute a family of genes encoding an MCO and a predicted component of the Type I secretion system.
球形微杆菌 ACM 3067 是一种属于α-变形菌纲的芽殖-菌丝细菌，能够将可溶性 Mn2+ 氧化为不溶性锰氧化物。从全基因组文库中鉴定出一个包含负责锰氧化的假定基因的黏粒，并采用引物步移法获得了 4350 bp 的新序列。对该序列的分析表明存在一个预测的三基因操纵子 moxCBA。moxA 基因产物与多铜氧化酶（MCOs）具有同源性，并包含 MCOs 共有的特征性四个铜结合基序（A、B、C 和 D）。moxA 的插入突变表明该基因对于锰氧化和漆酶样活性均至关重要。moxB 基因产物与革兰氏阴性菌 I 型分泌所必需的一类外膜蛋白具有同源性。moxBA 在其他锰氧化细菌中未被观察到，但在包括苜蓿中华根瘤菌 1021 和根癌农杆菌 C58 在内的几种细菌基因组中鉴定出了同源物。这些结果表明，moxBA 及其同源物构成了一个编码 MCO 和预测的 I 型分泌系统组分的基因家族。
