H-030. The Construction of Whole-Genome Oligomer Microarray and its Application for Transcriptome Analysis of Sulfur Acclimation in Cyanobacterium Synechocystis sp. PCC 6803

Z. Zhang1, N. D. Pendse1, K. N. Phillips2, A. B. Khodursky1;
1BioTechnology Inst., Univ. of Minnesota, St. Paul, MN, 2Univ. of Minnesota, St. Paul, MN.

Background: The unicellular photosynthetic Cyanobacterium Synechocystis sp. PCC 6803 is emerging as a model system for photobiological production of hydrogen, a clean and renewable fuel, from sunlight and water. Several macronutrient limitation conditions, including sulfur, were found to promote hydrogen evolution. However little is known about the underlying genome-wide transcriptional regulation mechanisms and their impact on the interactions between biomass accumulation, photosynthesis, respiration, and hydrogen production, which is critical for optimization of biological processes leading to energy storage. Results: We have designed and validated Synechocystis whole-genome oligonucleotide (70-mer) microarray as a platform to probe the genome-wide transcriptional regulation. As a first step the transcriptional responses to sulfur deprivation were investigated. The microarray data were independently verified by quantitative PCR. We found that transcriptional changes were relatively small, but significant. Sulfur deprivation conditions down-regulate protein-coding genes for transcriptional and translational machinery, light-harvesting antenna phycobilisome, photosystems I and II, Cytochrome b6/f complex and ATP synthase, while genes encoding for high-affinity sulfate transporter, phycobilisome degradation protein genes, along with many other genes of unknown function, were up-regulated. The transcriptional reprogramming significantly improved hydrogen production. Conclusion: Our microarray tool is well applicable for Synechocystis whole-genome transcription pattern investigations. Our data suggests that regulation of gene transcription in sulfur acclimation is critical for Synechocystis to sense nutrient limitations and tune its metabolism for efficiently utilization of available resources for survival and proliferation. The identified large portion of significantly regulated genes of unknown function implies that future systems biology studies is necessary to completely understand the metabolic and regulatory information, which may be exploited for improving the hydrogen productivity and sustainability by Cyanobacteria.