The Pkn22 Ser-Thr kinase in Nostoc PCC 7120: role of FurA and NtcA regulators and transcript profiling under nitrogen starvation and oxidative stressReportar como inadecuado

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BMC Genomics

, 16:557

First Online: 29 July 2015Received: 18 March 2015Accepted: 15 June 2015DOI: 10.1186-s12864-015-1703-1

Cite this article as: Yingping, F., Lemeille, S., González, A. et al. BMC Genomics 2015 16: 557. doi:10.1186-s12864-015-1703-1


BackgroundThe filamentous cyanobacterium Nostoc sp. strain PCC 7120 can fix N2 when combined nitrogen is not available. Furthermore, it has to cope with reactive oxygen species generated as byproducts of photosynthesis and respiration. We have previously demonstrated the synthesis of Ser-Thr kinase Pkn22 as an important survival response of Nostoc to oxidative damage. In this study we wished to investigate the possible involvement of this kinase in signalling peroxide stress and nitrogen deprivation.

ResultsQuantitative RT-PCR experiments revealed that the pkn22 gene is induced in response to peroxide stress and to combined nitrogen starvation. Electrophoretic motility assays indicated that the pkn22 promoter is recognized by the global transcriptional regulators FurA and NtcA. Transcriptomic analysis comparing a pkn22-insertion mutant and the wild type strain indicated that this kinase regulates genes involved in important cellular functions such as photosynthesis, carbon metabolism and iron acquisition. Since metabolic changes may lead to oxidative stress, we investigated whether this is the case with nitrogen starvation. Our results rather invalidate this hypothesis thereby suggesting that the function of Pkn22 under nitrogen starvation is independent of its role in response to peroxide stress.

ConclusionsOur analyses have permitted a more complete functional description of Ser-Thr kinase in Nostoc. We have decrypted the transcriptional regulation of the pkn22 gene, and analysed the whole set of genes under the control of this kinase in response to the two environmental changes often encountered by cyanobacteria in their natural habitat: oxidative stress and nitrogen deprivation.

KeywordsCyanobacteria Nostoc Ser-Thr kinase Oxidative stress Nitrogen starvation Signalling Microarray AbbreviationsEMSAElectrophoretic motility shift assays.

qRT-PCRQuantitative reverse transcription-polymerase chain reaction

Electronic supplementary materialThe online version of this article doi:10.1186-s12864-015-1703-1 contains supplementary material, which is available to authorized users.

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Autor: Fan Yingping - Sylvain Lemeille - Andrés González - Véronique Risoul - Yann Denis - Pierre Richaud - Otmane Lamrabet - M


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