A novel autoregulation mechanism of fnrN expression in Rhizobium leguminosarum bv viciae

被引:17
作者
Colombo, MV [1 ]
Gutiérrez, D [1 ]
Palacios, JM [1 ]
Imperial, J [1 ]
Ruiz-Argüeso, T [1 ]
机构
[1] Univ Politecn Madrid, ETS Ingn Agron, Microbiol Lab, Madrid, Spain
关键词
D O I
10.1046/j.1365-2958.2000.01867.x
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
The fnrN gene from Rhizobium leguminosarum UPM791 controls microaerobic expression of both nitrogen fixation and hydrogenase activities in symbiotic cells. Two copies of fnrN are present in this strain, one chromosomal (fnrN1) and the other located in the symbiotic plasmid (fnrN2). Their expression was studied by cloning the regulatory regions in lacZ promoter-probe vectors. The fnrN genes were found to be autoregulated: they are expressed only at basal levels under aerobic conditions; they are highly expressed under microaerobic conditions; and they are expressed at basal levels in the double mutant DG2 (fnrN1 fnrN2) under any condition. The promoters of both genes contain two FnrN-binding sequences (anaeroboxes), centred at positions -12.5 (proximal anaerobox) and -44.5 (distal anaerobox). Expression analysis and gel retardation experiments with fnrN1-derivative promoter mutants altered in key bases of the anaerobox sequences demonstrated that binding of FnrN1 to the distal anaerobox is necessary for microaerobic activation of transcription, and that binding of FnrN1 to the proximal anaerobox results in transcriptional repression. The apparent affinity of FnrN1 for the proximal anaerobox was fivefold lower than for the distal anaerobox, resulting in repression of transcription of fnrN1 only at high-FnrN1 concentrations. This positive and negative autoregulation mechanism ensures an equilibrated expression of fnrN in response to microaerobic conditions.
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页码:477 / 486
页数:10
相关论文
共 45 条
[1]   Region 2.5 of the Escherichia coli RNA polymerase sigma(70) subunit is responsible for the recognition of the 'extended -10' motif at promoters [J].
Barne, KA ;
Bown, JA ;
Busby, SJW ;
Minchin, SD .
EMBO JOURNAL, 1997, 16 (13) :4034-4040
[2]   FIXK, A GENE HOMOLOGOUS WITH FNR AND CRP FROM ESCHERICHIA-COLI, REGULATES NITROGEN-FIXATION GENES BOTH POSITIVELY AND NEGATIVELY IN RHIZOBIUM-MELILOTI [J].
BATUT, J ;
DAVERANMINGOT, ML ;
JACOBS, MDJ ;
GARNERONE, AM ;
KAHN, D .
EMBO JOURNAL, 1989, 8 (04) :1279-1286
[3]   Dissection of the transcription machinery for housekeeping genes of Bradyrhizobium japonicum [J].
Beck, C ;
Marty, R ;
Klausli, S ;
Hennecke, H ;
Gottfert, M .
JOURNAL OF BACTERIOLOGY, 1997, 179 (02) :364-369
[4]   AN FNR-LIKE PROTEIN ENCODED IN RHIZOBIUM-LEGUMINOSARUM BIOVAR VICIAE SHOWS STRUCTURAL AND FUNCTIONAL HOMOLOGY TO RHIZOBIUM-MELILOTI FIXK [J].
COLONNAROMANO, S ;
ARNOLD, W ;
SCHLUTER, A ;
BOISTARD, P ;
PUHLER, A ;
PRIEFER, UB .
MOLECULAR & GENERAL GENETICS, 1990, 223 (01) :138-147
[5]   CASCADE REGULATION OF NIF GENE-EXPRESSION IN RHIZOBIUM-MELILOTI [J].
DAVID, M ;
DAVERAN, ML ;
BATUT, J ;
DEDIEU, A ;
DOMERGUE, O ;
GHAI, J ;
HERTIG, C ;
BOISTARD, P ;
KAHN, D .
CELL, 1988, 54 (05) :671-683
[6]   GENETIC-REGULATION OF NITROGEN-FIXATION IN RHIZOBIA [J].
FISCHER, HM .
MICROBIOLOGICAL REVIEWS, 1994, 58 (03) :352-386
[7]   Identification of a surface of FNR overlapping activating region 1 that is required for repression of gene expression [J].
Green, J ;
Marshall, FA .
JOURNAL OF BIOLOGICAL CHEMISTRY, 1999, 274 (15) :10244-10248
[8]   Reconstitution of the [4Fe-4S] cluster in FNR and demonstration of the aerobic-anaerobic transcription switch in vitro [J].
Green, J ;
Bennett, B ;
Jordan, P ;
Ralph, ET ;
Thomson, AJ ;
Guest, JR .
BIOCHEMICAL JOURNAL, 1996, 316 :887-892
[9]  
GUEST JR, 1996, REGULATION GENE EXPR, P347
[10]   FnrN controls symbiotic nitrogen fixation and hydrogenase activities in Rhizobium leguminosarum biovar viciae UPM791 [J].
Gutierrez, D ;
Hernando, Y ;
Palacios, JM ;
Imperial, J ;
RuizArgueso, T .
JOURNAL OF BACTERIOLOGY, 1997, 179 (17) :5264-5270