King N D, Hojnacki D, O'Brian M R
Department of Biochemistry and Center for Microbial Pathogenesis, State University of New York at Buffalo, Buffalo, New York 14214, USA.
Appl Environ Microbiol. 2000 Dec;66(12):5469-71. doi: 10.1128/AEM.66.12.5469-5471.2000.
Plant host-derived proline is proposed to serve as an energy source for rhizobia in the rhizosphere and in symbiotic root nodules. The Bradyrhizobium japonicum proC gene was isolated, and a proC mutant strain that behaved as a strict proline auxotroph in culture was constructed. The proC strain elicited undeveloped nodules on soybeans that lacked nitrogen fixation activity and plant hemoglobin. We conclude that the proC gene is essential for symbiosis and suggest that the mutant does not obtain an exogenous supply of proline in association with soybeans sufficient to satisfy its auxotrophy.
植物宿主来源的脯氨酸被认为是根际和共生根瘤中根瘤菌的能量来源。分离出了慢生根瘤菌的脯氨酸合成酶基因proC，并构建了一个在培养中表现为严格脯氨酸营养缺陷型的proC突变菌株。该proC菌株在大豆上诱导出未发育成熟的根瘤，这些根瘤缺乏固氮活性和植物血红蛋白。我们得出结论，proC基因对于共生至关重要，并表明该突变体在与大豆共生时无法获得足以满足其营养缺陷的外源脯氨酸供应。
