Submitted to: American Society of Plant Biologists Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: March 2, 2008
Publication Date: N/A
Technical Abstract: Benzoquinone reductase (BR; EC 18.104.22.168) is an enzyme that catalyzes the bivalent redox reactions of quinones without the production of free radical intermediates. Using 2-D PAGE comparisons, two proteins were found to be up-regulated in wild-type cotton ovules during the fiber initiation stage but not in the fiberless line SL 1-7-1. These proteins were excised from the gel, partially sequenced and identified to be BR isoforms. PCR was used to amplify the full length coding regions of 609 bp together and once cloned, the restriction enzyme HindIII was used to distinguish the clones encoding the BR1 (1 site) and BR2 (2 sites) isoforms. Both deduced protein sequences had 203 residues, though they differed at 14 residues. The molecular mass and pIs were similar between the measured protein (2D PAGE) and the theoretical protein (deduced). Heterologous proteins BR1 and BR2 were produced for further study by ligating the BR1 and BR2 clones in frame into the alpha-factor secretion sequence in pPICZ alpha A vector and expressed with Pichia pastoris. Both BR1 and BR2 were approximately 26.5 kDa and did enzymatically reduce 2,6 dimethoxybenzoquinone similar to the fungal BR.