The influence of acetyl phosphate on DspA signalling in the Cyanobacterium Synechocystis sp. PCC6803.

S Shawn Morrison,Mark K Ashby,Conrad W Mullineaux

doi:10.1186/1471-2180-5-47

Abstract

BackgroundThe dspA (hik33) gene, coding for a putative sensory histidine kinase, is conserved in plastids (ycf26) and cyanobacteria. It has been linked with a number of different stress responses in cyanobacteria.ResultsWe constructed an insertional mutant of dspA (ycf26) in Synechocystis 6803. We found little phenotypic effect during nitrogen starvation. However, when the mutation was combined with deletion of the pta gene coding for phosphotransacetylase, a more significant phenotype was observed. Under nitrogen starvation, the pta/dspA double mutant degrades its phycobilisomes less than the wild type and still has about half of its chlorophyll-protein complexes.ConclusionOur data indicates that acetyl-phosphate-dependent phosphorylation of response regulator(s) overlaps with DspA-dependent signalling of the degradation of chlorophyll-protein complexes (and to a lesser extent phycobilisomes) in Synechocystis 6803.

Highlights

The dspA gene, coding for a putative sensory histidine kinase, is conserved in plastids and cyanobacteria
We show that the inactivation of dspA has little phenotypic effect under nitrogen starvation, unless the mutation is combined with deletion of the pta gene
Analysis of cyanobacterial and plastid deduced Ycf26 protein sequences The deduced amino acid sequences for Ycf26 from 15 available cyanobacterial annotated genome sequences and the red algal species Porphyra purpurea, Gracilaria tenuistipitata and Cyanidium caldarium were analysed by Pfam and SMART

Summary

Introduction

The dspA (hik33) gene, coding for a putative sensory histidine kinase, is conserved in plastids (ycf26) and cyanobacteria It has been linked with a number of different stress responses in cyanobacteria. Two-component signal transduction pathways form a major part of the signalling machinery, mediating adaptive responses to a broad range of environmental stimuli [2,3,4]. In response to such stimuli, a sensor kinase autophosphorylates an internal histidine residue, and transfers the phosphate to a conserved aspartate residue on the receiver domain of its cognate response regulator. Chamnongpol & Groisman [11] identified acetyl phosphate as the phosphate donor for a mutant version of the response regulator PhoP (PhoP*) and showed that inactivation of the pta gene abolished PhoP*-mediated (page number not for citation purposes)

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