Differential expression of the glucose transporter gene glcH in response to glucose and light in marine picocyanobacteria
- Published
- Accepted
- Subject Areas
- Ecology, Marine Biology, Microbiology, Molecular Biology, Biological Oceanography
- Keywords
- glucose uptake, gene expression, transcriptional regulation, marine picocyanobacteria, darkness
- Copyright
- © 2018 Moreno-Cabezuelo et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2018. Differential expression of the glucose transporter gene glcH in response to glucose and light in marine picocyanobacteria. PeerJ Preprints 6:e27423v1 https://doi.org/10.7287/peerj.preprints.27423v1
Abstract
Background
Our team discovered that Prochlorococcus can take up glucose, in a process that changes the transcriptional pattern of several genes involved in glucose metabolization. We have also shown that glcH encodes a very high affinity glucose transporter, and that glucose is taken up by natural Prochlorococcus populations. We demonstrated that the kinetic parameters of glucose uptake show significant diversity in different Prochlorococcus and Synechococcus strains. Here we tested whether the transcriptional response of glcH to several glucose concentrations and light conditions was also different depending on the studied strain.
Methods
Cultures were grown in the light, supplemented with five different glucose concentrations or subjected to darkness, and cells harvested after 24 h of treatment. qRT-PCR was used to determine glcH expression in four Prochlorococcus and two Synechococcus strains.
Results
In all studied strains glcH was expressed in the absence of glucose, and it increased upon glucose addition to cultures. The changes differed depending on the strain, both in the magnitude and in the way cells responded to the tested glucose concentrations. Unlike the other strains, Synechococcus BL107 showed the maximum glucose uptake at 5 nM glucose. Darkness induced a strong decrease in glcH expression, especially remarkable in Prochlorococcus MIT9313.
Discussion
Our results suggest that marine picocyanobacteria are actively monitoring the availability of glucose, to upregulate glcH expression in order to exploit the presence of sugars in the environment. The diverse responses observed in different strains suggest that the transcriptional regulation of glucose uptake has been adjusted by evolutive selection. Darkness promotes a strong decrease in glcH expression in all studied strains, which fits with previous results on glucose uptake in Prochlorococcus. Overall, this work reinforces the importance of mixotrophy for marine picocyanobacteria.
Author Comment
This is a submission to PeerJ for review.