Burkholderia sp. NCIMB 10467菌株中原儿茶酸3, 4-双加氧酶基因的分子克隆和生化特性研究（英文稿）

NCIMB 10467是一株木质素降解菌, 根据其16S rDNA序列将其重新分类为Burkholderia菌属。研究显示, 在NCIMB 10467菌株中, 不同的底物可以诱导该菌株对于原儿茶酸的多种代谢形式。根据克隆到的一段原儿茶酸邻位开环酶, 即原儿茶酸3, 4-双加氧酶(P34D; EC 1.13.11.3) a-亚基的保守序列, 通过染色体步移的方法, 得到一段9505 bp的DNA片段。序列分析显示, 在这段9.5 kb的DNA片段中, 两个可能的开放阅读框pcaG 和 pcaH分别编码P34D的a-亚基和b-亚基。将pcaGH克隆并在大肠杆菌中进行表达后, 可以检测到P34D的活性。而pcaH在NCIMB 10467菌株中的敲除则使该菌完全丧失了代谢原儿茶酸的能力。由此证实, 克隆到的pcaGH基因确实编码原儿茶酸3, 4-双加氧酶, 并且对于NCIMB 10467菌株对原儿茶酸的代谢是必需的。

Molecular Cloning and Biochemical Characterization of Protocatechuate 3,4-dioxygenase in Burkholderia sp. NCIMB 10467

Strain NCIMB 10467, a lignin degrader, was reclassified as genus Burkholderia according to its 16S rDNA sequence. It seems that the metabolism of protocatechuate by this strain is diverse under the induction of various substrates. A 9505-bp DNA fragment extending from a conserved region of the gene, which encodes a subunit of ortho cleavage protocatechuate 3,4-dioxygenase (P34D; EC 1.13.11.3), was obtained by genome walking. Sequence analysis revealed two deduced open reading frames, pcaG and pcaH, encoding the a and b subunits of P34D respectively in this fragment. The P34D activity could be detected when pcaGH were expressed in E. coli and the disruption of pcaH in strain NCIMB 10467 has lead to loss of its ability to catabolize protocatechuate. It was proved that the cloned pcaGH were encoding a functional protocatechuate 3,4-dioxygenase which was necessary for the protocatechuate metabolism in this strain.