Department of Pediatrics, USDA/ARS Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX 77030-2600, USA.
FEMS Microbiol Lett. 2010 Mar;304(2):177-82. doi: 10.1111/j.1574-6968.2010.01895.x. Epub 2010 Jan 8.
Although the biosynthesis of oxalic acid is known to occur in a number of bacteria, the mechanism(s) regulating its production remains largely unknown. To date, there is no report on the identification of an oxalic acid biosynthetic pathway gene from bacteria. In an attempt to identify such a gene(s), a mutant screen was conducted using the simple oxalic acid-producing phytopathogenic bacterium, Burkholderia glumae. Four mutants that failed to produce oxalic acid were isolated from a transposon-mutagenized B. glumae library and named Burkholderia oxalate defective (Bod)1. DNA sequence analysis revealed that each mutant contained an insertion event at different sites in the same ORF, which we referred to as the oxalate biosynthetic component (obc)A locus. Complementation of the Bod1 mutant with the obcA gene, however, resulted only in a partial restoration of the oxalic acid-producing phenotype. Further complementation studies utilizing a larger DNA fragment encompassing the obcA locus coupled with deletion mutagenesis led to the identification of another ORF that we named the obcB locus, which was essential for higher levels of oxalic acid production. Transcript analysis indicated that both obcA and obcB are coexpressed and encoded on a single polycistron message.
尽管已知许多细菌都能合成草酸，但草酸产生的调控机制在很大程度上仍然未知。迄今为止，尚无关于从细菌中鉴定草酸生物合成途径基因的报道。为了鉴定这样的基因，我们使用简单的产草酸植物病原菌伯克霍尔德氏菌进行了突变筛选。从转座子诱变的伯克霍尔德氏菌文库中分离出 4 个不能产生草酸的突变体，并将其命名为 Burkholderia oxalate defective (Bod)1。DNA 序列分析表明，每个突变体在相同 ORF 的不同位点都有一个插入事件，我们将其称为草酸生物合成成分（obc）A 基因座。然而，用 obcA 基因对 Bod1 突变体进行互补仅导致草酸产生表型的部分恢复。进一步利用包含 obcA 基因座的更大 DNA 片段进行互补研究，并结合缺失诱变，鉴定了另一个必需的 ORF，我们将其命名为 obcB 基因座，该基因座对于更高水平的草酸产生是必需的。转录分析表明，obcA 和 obcB 均共表达，并编码在单个多顺反子消息上。
