Fine‐tuning modulation of oxidation-mediated posttranslational control of Bradyrhizobium diazoefficiens FixK2 transcription factor

Parejo Trevino, Sergio, Cabrera Rodriguez, Juan J., Jimenez-Levia, Andrea, Tomas-Gallardo, Laura, Bedmar, Eulogio J., Gates, Andrew J. and Mesa, Socorro (2022) Fine‐tuning modulation of oxidation-mediated posttranslational control of Bradyrhizobium diazoefficiens FixK2 transcription factor. International Journal of Molecular Sciences, 23 (9). ISSN 1661-6596

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Abstract

FixK2 is a CRP/FNR‐type transcription factor that plays a central role in a sophisticated regulatory network for the anoxic, microoxic and symbiotic lifestyles of the soybean endosymbiont Bradyrhizobium diazoefficiens. Apart of the balanced expression of the fixK2 gene under microoxic conditions (induced by the two‐component regulatory system FixLJ and negatively auto‐repressed), FixK2 activity is posttranslationally controlled by proteolysis, and by oxidation of a singular cysteine residue (C183) near its DNA‐binding domain. To simulate permanent oxidation of FixK2, we replaced C183 for aspartic acid. Purified C183D FixK2 protein showed both low DNA binding and in vitro transcriptional activation from the promoter of the fixNOQP operon, required for respiration under symbiosis. However, in a B. diazoefficiens strain coding for C183D FixK2, expression of a fixNOQP’‐‘lacZ fusion was similar to that in the wild type, when both strains were grown microoxically. The C183D FixK2 encoding strain also showed a wild‐type phenotype in symbiosis with soybeans, and increased fixK2 gene expression levels and FixK2 protein abundance in cells. These two latter observations together with a global transcriptional profile of the microoxically cultured C183D FixK2 encoding strain suggest the existence of a finely tuned regulatory strategy to counterbalance the oxidation‐mediated inactivation of FixK2 in vivo.

Item Type: Article
Additional Information: Funding: This research was funded by grants AGL2015-63651-P and PID2020-114330GB-100 (Ministerio de Ciencia e Innovación, Spain) to S.M. Grants P12-AGR-1968 and P18-RT-1401 to E.J.B. and S.M., respectively, and continuous support of group BIO-275 (Junta de Andalucía, Spain), are also acknowledged. Work in A.J.G.’s laboratory was supported by grants BB/M00256X/1 and BB/S008942/1 (BBSRC, UK). S.P. was supported by the FPU Program (Ministerio de Educación, Cultura y Deporte, presently Ministerio de Universidades, Spain; grant FPU2015/04716).
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: LivePure Connector
Date Deposited: 29 Apr 2022 08:32
Last Modified: 13 May 2022 14:30
URI: https://ueaeprints.uea.ac.uk/id/eprint/84851
DOI: 10.3390/ijms23095117

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