Ibrahim, Iskander, Blunskyte, Modesta and Thompson, Elinor ORCID: 0000-0002-6434-9290 (2017) The cyanobacterial rhomboid protease is a new regulator of the CCM. In: Plastid Preview, 4-5 September 2017, University of Cambridge.

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Abstract

The 'rhomboid' membrane-located proteases are almost ubiquitous across evolution, and act as activators of diverse proteins and signalling pathways by cleaving their specific, membrane-sequestered substrates. The family has a conserved 6/7-transmembrane structure that has been solved in crystal structures of bacterial enzymes such as Escherichia coli GlpG. Ironically, however, most work has been carried out on eukaryotic representatives and there is no work on rhomboids of photosynthetic prokaryotes. Following our study of the Arabidopsis thaliana chloroplast RBL10 protease, we identified cyanobacterial orthologues with the aim of discovering if roles might be conserved between these and organellar rhomboids.

Molecular biology and reverse-genetics studies were made on slr1461, a mutant in the single rhomboid protease of Synechocystis sp. PCC 6803. When photosynthetic parameters were investigated, it could be seen that inactivation of slr1461 did not affect nonphotochemical quenching, unlike the chloroplast rbl10 mutant, but Slr1461 was required for reduction of photosynthetic activity in mixotrophic conditions. This reduction allows cyanobacteria to avoid expending energy on the uptake of CO2 when an organic carbon source can be utilised: as might be expected, therefore, Slr1461 transcription was linked with downregulation of genes encoding proteins facilitating high-affinity CO2 import under high CO2 and mixotrophic conditions. Quantitative RT-PCR of CCM network genes suggested that Slr1461 is located upstream of known regulators, including another membrane protease, the slr0228 FtsH, and a central, controlling transcription factor NdhR.

Item Type:	Conference or Conference Paper (Speech)
Uncontrolled Keywords:	Photosynthesis, Membrane, Protease
Subjects:	Q Science > Q Science (General)
Faculty / School / Research Centre / Research Group:	Faculty of Engineering & Science Faculty of Education, Health & Human Sciences > School of Human Sciences (HUM)
Related URLs:	Organisation
Last Modified:	09 Oct 2021 04:45
URI:	http://gala.gre.ac.uk/id/eprint/17631

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