Masai Eiji, Katayama Yoshihiro, Fukuda Masao
Department of Bioengineering, Nagaoka University of Technology, Japan.
Biosci Biotechnol Biochem. 2007 Jan;71(1):1-15. doi: 10.1271/bbb.60437. Epub 2007 Jan 7.
Lignins are the most abundant aromatic compounds in nature, and their decomposition is essential to the terrestrial carbon cycle. White rot fungi secreting phenol oxidases are assumed to be involved in the initial degradation of native lignin, whereas bacteria play a main role in the mineralization of lignin-derived low-molecular-weight compounds in soil. There are a number of reports on the degradation pathways for lignin-derived aromatic compounds, but their catabolism has not been enzymatically or genetically characterized. Sphingomonas paucimobilis SYK-6 is one of the best-characterized lignin-degrading bacteria. It can grow on a wide variety of lignin-related biaryls and monoaryls, including beta-aryl ether, biphenyl, diarylpropane, and phenylpropane. These compounds are degraded via the protocatechuate (PCA) 4,5-cleavage pathway or multiple 3-O-methylgallate (3MGA) catabolic pathways. In this review, the enzyme systems for beta-aryl ether and biphenyl degradation, O demethylation linked with one carbon metabolism, the PCA 4,5-cleavage pathway, and the multiple 3MGA catabolic pathways in SYK-6 are outlined.
木质素是自然界中含量最丰富的芳香族化合物，其分解对陆地碳循环至关重要。分泌酚氧化酶的白腐真菌被认为参与天然木质素的初始降解，而细菌在土壤中木质素衍生的低分子量化合物的矿化过程中起主要作用。关于木质素衍生的芳香族化合物的降解途径已有许多报道，但其分解代谢尚未在酶学或遗传学上得到表征。少动鞘氨醇单胞菌SYK-6是最具代表性的木质素降解细菌之一。它可以在多种与木质素相关的联苯和单芳基化合物上生长，包括β-芳基醚、联苯、二芳基丙烷和苯丙烷。这些化合物通过原儿茶酸（PCA）4,5-裂解途径或多种3-O-甲基没食子酸（3MGA）分解代谢途径降解。在这篇综述中，概述了SYK-6中β-芳基醚和联苯降解的酶系统、与一碳代谢相关的O-去甲基化、PCA 4,5-裂解途径以及多种3MGA分解代谢途径。
