Wexler M, Todd J D, Kolade O, Bellini D, Hemmings A M, Sawers G, Johnston A W B
School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK.
John Innes Centre, Norwich Research Park, Colney Lane, Norwich NR4 7UH, UK.
Microbiology (Reading). 2003 May;149(Pt 5):1357-1365. doi: 10.1099/mic.0.26130-0.
Rhizobium leguminosarum fur mutants were unaffected in Fe-dependent regulation of several operons that specify different Fe uptake systems, yet cloned R. leguminosarum fur partially corrected an Escherichia coli fur mutant and R. leguminosarum Fur protein bound to canonical fur boxes. The lack of a phenotype in fur mutants is not due to functional redundancy with Irr, another member of the Fur superfamily found in the rhizobia, since irr fur double mutants are also unaffected in Fe-responsive regulation of several operons involved in Fe uptake. Neither Irr nor Fur is needed for symbiotic N(2) fixation on peas. As in Bradyrhizobium japonicum, irr mutants accumulated protoporphyrin IX. R. leguminosarum irr is not regulated by Fur and its Irr protein lacks the motif needed for haem-dependent post-translational modification that occurs in B. japonicum Irr. The similarities and differences in the Fur superfamily in the rhizobia and other Gram-negative bacteria are discussed.
豆科根瘤菌（Rhizobium leguminosarum）的fur突变体在几种指定不同铁摄取系统的操纵子的铁依赖性调控中未受影响，但克隆的豆科根瘤菌fur部分校正了大肠杆菌的fur突变体，并且豆科根瘤菌Fur蛋白与典型的fur框结合。fur突变体中缺乏表型并非由于与Irr（根瘤菌中发现的Fur超家族的另一个成员）功能冗余所致，因为irr fur双突变体在参与铁摄取的几个操纵子的铁响应调控中也未受影响。豌豆上的共生固氮作用既不需要Irr也不需要Fur。与日本慢生根瘤菌（Bradyrhizobium japonicum）一样，irr突变体积聚原卟啉IX。豆科根瘤菌irr不受Fur调控，其Irr蛋白缺乏日本慢生根瘤菌Irr中发生的血红素依赖性翻译后修饰所需的基序。本文讨论了根瘤菌和其他革兰氏阴性细菌中Fur超家族的异同。
