Original Research ARTICLE
THE SYNECHOCYSTIS SP. PCC 6803 GENOME ENCODES UP TO FOUR 2-PHOSPHOGLYCOLATE PHOSPHATASES
- 1Institute of Biosciences, University of Rostock, Germany
- 2Department Leben, Licht & Materie, Interdisziplinäre Fakultät, Universität Rostock, Germany
- 3Institut für Pflanzenphysiologie, Universität Rostock, Germany
- 4Centre of Advanced Study in Botany, Faculty of Science, Banaras Hindu University, India
- 5Institut für Angewandte Ökologie und Phykologie, Universität Rostock, Germany
- 6Department of Plant and Environmental Sciences, Hebrew University of Jerusalem, Israel
- 7Max-Planck-Institut für Molekulare Pflanzenphysiologie, Germany
Photorespiratory phosphoglycolate (2PG) metabolism is essential for cyanobacteria, algae, and plants. The first enzyme of the pathway, 2PG phosphatase (PGPase), is known from plants and algae but was scarcely investigated in cyanobacteria. In silico analysis revealed four candidate genes (slr0458, slr0586, sll1349 and slr1762I) in the genome of the model cyanobacterium Synechocystis sp. PCC 6803 that all belong to the 2-haloacid dehalogenase (HAD) superfamily and could possibly encode PGPase proteins. However, in contrast to known algal and plant PGPases, the putative cyanobacterial PGPases belong to another HAD subfamily implying that PGPases in eukaryotic phototrophs did not originate from cyanobacterial PGPases. To verify their function, these four genes were inactivated both individually and in combination. A mild high-CO2-requiring (HCR) growth phenotype typical for photorespiratory mutants was observed only in ∆sll1349. Combinatorial inactivation enhanced the HCR phenotype in specific double and triple mutants. Heterologous expression of the putative cyanobacterial PGPases in E. coli led to higher PGPase activities in crude cell extracts, but only the purified Slr0458 protein showed PGPase activity. Hence, we propose that a consortium of up to four photorespiratory PGPases may initiate photorespiratory 2PG metabolism in Synechocystis. We suggest that redundancy of this essential enzyme activity could be related to the highly adaptive lifestyle of cyanobacteria such as Synechocystis sp. PCC 6803, which allows them to grow under very diverse conditions.
Keywords: Cyanobactaria, Haloacid dehalogenase, mutant, Phosphoglycolate phosphatase, photorespiration
Received: 25 Sep 2018;
Accepted: 05 Nov 2018.
Edited by:Cornelia Spetea, University of Gothenburg, Sweden
Reviewed by:Anja Schneider, Ludwig Maximilian University of Munich, Germany
Cheng-Cai Zhang, Chinese Academy of Sciences, China
Copyright: © 2018 Hagemann, Rai, Lucius, Kern, Bauwe, Kaplan and Kopka. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Prof. Martin Hagemann, University of Rostock, Institute of Biosciences, Rostock, D-18059, Germany, email@example.com