A1543 is a Potential Bridge Between Cellular Redox State and RNA Processing

Abstract

Synechococcus Sp. PCC 7002 is a rapidly growing, genetically tractable, photosynthetic microbe of industrial interest. Understanding how gene expression and carbon fixation are regulated in PCC 7002 is essential for its advancement as an industrial microbe. Towards that aim, we are investigating a cyanobacterial homolog to E. coli RNase II/R, A1543, that we hypothesize regulates gene expression and other cellular processes in response to changes in cellular redox state.A1543 is an RNA binding protein with three RNA binding domains ‐ two OB folds and an S1 domain. Multiple alignment of PCC 7002 A1543 to RNase II/R homologues in other cyanobacteria show conservation across the genre of two cysteines. Threading of the A1543 sequence onto the E. coli RNase II crystal structure shows that these two cysteines sit in L12 and b2 of the first OB fold, within 4 angstroms of each other, and thus could potentially interact via a disulfide bond.To characterize the role of A1543 in vivo we constructed a segregated A1543 knockout line, DA1543, which shows, as previously reported in the literature, defects in both pigmentation and growth. Additionally, we found that our DA1543 line shows resistance to the carbonic anhydrase acetazolamide compared to wild‐type. This phenotype had been characterized before in a related species, Synechocystis sp. 6803. We have found concentrations of acetazolamide that is lethal and inhibitory to both wildtype and DA1543 cells in several different growth conditions. Interestingly, at 3% CO2, acetazolamide has a greater effect on growth than in air for both cell lines.A1543 is a potential link between the cellular redox state and RNA processing in cyanobacterial cells via changes of RNA binding behavior through oxidation or reduction of a disulfide bridge in a conserved OB‐fold. Understanding if this type of regulation is occurring and how it affects cyanobacterial gene expression and carbon fixation will enable further development of Synechococcus Sp. PCC 7002 as an industrial research organism.Support or Funding InformationPatrick Thomas is supported by the NIH T32 Biophysics training grantThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.