Imperial College London
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ProfessorIolyKotta-Loizou

Faculty of Natural Sciences, Department of Life Sciences

Honorary Lecturer
 
 
 
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Contact

 

i.kotta-loizou13

 
 
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Location

 

Sir Alexander Fleming BuildingSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Waite:2021:10.3389/fmicb.2021.718487,
author = {Waite, C and Lindstrom-Battle, A and Bennett, M and Carey, M and Kotta-Loizou, I and Hong, C and Buck, M and Schumacher, J},
doi = {10.3389/fmicb.2021.718487},
journal = {Frontiers in Microbiology},
pages = {1--20},
title = {Resource allocation during the transition to diazotrophy in Klebsiella oxytoca},
url = {http://dx.doi.org/10.3389/fmicb.2021.718487},
volume = {12},
year = {2021}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - Free-living nitrogen-fixing bacteria can improve growth yields of some non-leguminous plants and, if enhanced through bioengineering approaches, have the potential to address major nutrient imbalances in global crop production by supplementing inorganic nitrogen fertilizers. However, nitrogen fixation is a highly resource-costly adaptation and is de-repressed only in environments in which sources of reduced nitrogen are scarce. Here we investigate nitrogen fixation (nif) gene expression and nitrogen starvation response signalling in the model diazotroph Klebsiella oxytoca (Ko) M5a1 during ammonium depletion and the transition to growth on atmospheric N2. Exploratory RNA-sequencing revealed that over 50% of genes were differentially expressed under diazotrophic conditions, among which the nif genes are among the most highly expressed and highly upregulated. Isotopically labelled QconCAT standards were designed for multiplexed, absolute quantification of Nif and nitrogen-stress proteins via multiple reaction monitoring mass spectrometry (MRM-MS). Time-resolved Nif protein concentrations were indicative of bifurcation in the accumulation rates of nitrogenase subunits (NifHDK) and accessory proteins. We estimate that the nitrogenase may account for more than 40% of cell protein during diazotrophic growth and occupy approximately half the active ribosome complement. The concentrations of free amino acids in nitrogen-starved cells were insufficient to support the observed rates of Nif protein expression. Total Nif protein accumulation was reduced 10-fold when the NifK protein was truncated and nitrogenase catalysis lost (nifK1-1203), implying that reinvestment of de novo fixed nitrogen is essential for further nif expression and a complete diazotrophy transition. Several amino acids accumulated in non-fixing ΔnifLA and nifK1-1203 mutants, while the rest remained highly stable despite prolonged N starvation. Monitoring post-translational uridylylation of the PII-type
AU  - Waite,C
AU  - Lindstrom-Battle,A
AU  - Bennett,M
AU  - Carey,M
AU  - Kotta-Loizou,I
AU  - Hong,C
AU  - Buck,M
AU  - Schumacher,J
DO  - 10.3389/fmicb.2021.718487
EP  - 20
PY  - 2021///
SN  - 1664-302X
SP  - 1
TI  - Resource allocation during the transition to diazotrophy in Klebsiella oxytoca
T2  - Frontiers in Microbiology
UR  - http://dx.doi.org/10.3389/fmicb.2021.718487
UR  - https://www.frontiersin.org/articles/10.3389/fmicb.2021.718487/abstract
UR  - http://hdl.handle.net/10044/1/90597
VL  - 12
ER  -
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