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NtrC-dependent regulatory network for nitrogen assimilation in Pseudomonas putida
Ana B Hervás1, Inés Canosa, Richard Little
1Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide/CSIC, Seville, Spain.
Journal of Bacteriology
|August 4, 2009
Summary
Nitrogen regulation in Pseudomonas putida KT2440 is simpler than in E. coli. The NtrC protein directly regulates key genes like glnK, codB, and ureD, bypassing the need for the Nac protein found in enterobacteria.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Pseudomonas putida KT2440 is a model organism for biodegradation.
- Nitrogen regulation mechanisms in P. putida are not well understood.
- Enterobacterial nitrogen regulation involves NtrC and Nac proteins.
Purpose of the Study:
- To elucidate the nitrogen regulatory network in P. putida KT2440.
- To compare nitrogen regulation between P. putida and E. coli.
- To identify key regulatory proteins and their targets in P. putida.
Main Methods:
- Functional analysis of NtrC proteins from P. putida and E. coli.
- Footprinting analysis to identify NtrC binding sites.
- In vitro transcription assays to study gene regulation.
- Analysis of nitrogen-regulated genes (glnK, codB, dppA, ureD).
Main Results:
- P. putida and E. coli NtrC proteins are functionally equivalent.
- NtrC directly activates transcription of glnK, codB, and ureD in a sigma(N)-dependent manner.
- Integration host factor is required for glnK promoter activity.
- dppA is not regulated by NtrC.
- P. putida lacks the Nac protein, and regulation of codB and ureD occurs directly via NtrC.
Conclusions:
- P. putida possesses a simplified nitrogen regulatory network compared to enterobacteria.
- NtrC plays a central role in P. putida nitrogen metabolism, directly regulating key genes.
- The absence of Nac is compensated by direct NtrC regulation, highlighting pathway divergence.
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