Nitrogen regulatory protein C-controlled genes of Escherichia coli: scavenging as a defense against nitrogen limitation.
Nitrogen regulatory protein C (NtrC) of enteric bacteria activates transcription of genes/operons whose products minimize the slowing of growth under nitrogen-limiting conditions. To reveal the NtrC regulon of Escherichia coli we compared mRNA levels in a mutant strain that overexpresses NtrC-activated genes [glnL(Up)] to those in a strain with an ntrC (glnG) null allele by using DNA microarrays. Both strains could be grown under conditions of nitrogen excess. Thus, we could avoid differences in gene expression caused by slow growth or nitrogen limitation per se. Rearranging the spot images from microarrays in genome order allowed us to detect all of the operons known to be under NtrC control and facilitated detection of a number of new ones. Many of these operons encode transport systems for nitrogen-containing compounds, including compounds recycled during cell-wall synthesis, and hence scavenging appears to be a primary response to nitrogen limitation. In all, approximately 2% of the E. coli genome appears to be under NtrC control, although transcription of some operons depends on the nitrogen assimilation control protein, which serves as an adapter between NtrC and final sigma(70)-dependent promoters.
Zimmer
D P
DP
Departments of Plant and Microbial Biology and Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
Soupene
E
E
Lee
H L
HL
Wendisch
V F
VF
Khodursky
A B
AB
Peter
B J
BJ
Bender
R A
RA
Kustu
S
S
D019677:Artificial Gene Fusion; D001426:Bacterial Proteins / Q000235:genetics*; D005591:Chemical Fractionation; D004268:DNA-Binding Proteins / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D007763:Lac Operon; D009584:Nitrogen / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D051922:PII Nitrogen Regulatory Proteins; D019897:Periplasm / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000235:genetics; D011494:Protein Kinases / Q000235:genetics; D015534:Trans-Activators / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics
D001426:Bacterial Proteins; C097229:Cbl protein, E coli; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C072712:NAC protein, bacteria; C489526:Nac protein, E coli; D051922:PII Nitrogen Regulatory Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C497876:glnG protein, E coli; D011494:Protein Kinases; C055699:protein kinase-phosphatase NTRB; D010749:Phosphoprotein Phosphatases; D009584:Nitrogen