Nowak Petri, Soupas Laura, Thomas-Oates Jane, Lindström Kristina
Department of Applied Chemistry and Microbiology, PO Box 56, 00014 University of Helsinki, Helsinki, Finland.
Carbohydr Res. 2004 Apr 28;339(6):1061-7. doi: 10.1016/j.carres.2004.02.013.
Sinorhizobium arboris and S. kostiense are rhizobia that nodulate the tropical leguminous trees Acacia senegal and Prosopis chilensis. The lipochito-oligosaccharidic signalling molecules (LCOs) of S. arboris HAMBI 2361 and S. kostiense HAMBI 2362 were analyzed by mass spectrometry. The major LCOs produced by the strains were shown to be pentameric, acylated with common fatty acids, N-methylated, O-6-carbamoylated and partially sulfated, as are the LCOs characterized to date for other Acacia-nodulating rhizobia. Besides the major LCOs the two strains produced (i) tetrameric LCOs, (ii) LCOs acylated with fatty acids other than those commonly found, (iii) LCOs with only an acyl substituent and (iv) noncarbamoylated LCOs. Production of LCOs (i) to (iii) are novel among Acacia-nodulating rhizobia. The roles of the different structural characteristics of LCOs in the rhizobium-A. senegal symbiosis are discussed. Specific structural features of the LCOs are proposed to be important in the selection of effective nitrogen-fixing rhizobia by A. senegal.
树木中华根瘤菌和科氏中华根瘤菌是能使热带豆科树木塞内加尔金合欢和智利牧豆树结瘤的根瘤菌。通过质谱分析法对树木中华根瘤菌HAMBI 2361和科氏中华根瘤菌HAMBI 2362的脂壳寡糖信号分子（LCOs）进行了分析。结果表明，这些菌株产生的主要LCOs为五聚体，被常见脂肪酸酰化、N-甲基化、O-6-氨甲酰化并部分硫酸化，这与迄今已鉴定的其他能使金合欢结瘤的根瘤菌的LCOs情况相同。除了主要的LCOs外，这两种菌株还产生了（i）四聚体LCOs，（ii）被不常见脂肪酸酰化的LCOs，（iii）仅带有一个酰基取代基的LCOs，以及（iv）非氨甲酰化的LCOs。LCOs（i）至（iii）的产生在能使金合欢结瘤的根瘤菌中是新颖的。文中讨论了LCOs不同结构特征在根瘤菌与塞内加尔金合欢共生关系中的作用。有人提出，LCOs的特定结构特征对于塞内加尔金合欢选择有效的固氮根瘤菌很重要。
