Data_Sheet_4_Quantitative Proteomic Profiling of Marine Diatom Skeletonema dohrnii in Response to Temperature and Silicate Induced Environmental Stress.doc

Global warming is expected to reduce the nutrient concentration in the upper ocean and affect the physiology of marine diatoms, but the underlying molecular mechanisms controlling these physiological changes are currently unknown. To understand these mechanisms, here we investigated iTRAQ based proteomic profiling of diatom Skeletonema dohrnii in a multifactorial experimental with a combining change of temperature and silicate concentrations. In total, 3369 differently abundant proteins were detected in four different environmental conditions, and the function of all proteins was identified using Gene Ontology and KEGG pathway analysis. For discriminating the proteome variation among samples, multivariate statistical analysis (PCA, PLS-DA) was performed by comparing the protein ratio differences. Further, performing pathway analysis on diatom proteomes, we here demonstrated downregulation of photosynthesis, carbon metabolism, and ribosome biogenesis in the cellular process that leads to decrease the oxidoreductase activity and affects the cell cycle of the diatom. Using PLS-DA VIP score plot analysis, we identified 15 protein biomarkers for discriminating studied samples. Of these, five proteins or gene (rbcL, PRK, atpB, DNA-binding, and signal transduction) identified as key biomarkers, induced by temperature and silicate stress in diatom metabolism. Our results show that proteomic finger-printing of S. dohrnii with different environmental conditions adds biological information that strengthens marine phytoplankton proteome analysis.

全球变暖预计将降低上层海洋的营养盐浓度，并影响海洋硅藻的生理机能，但调控此类生理变化的潜在分子机制目前仍未阐明。为解析该类机制，本研究通过温度与硅酸盐浓度联合变化的多因子实验，对多氏骨条藻（*Skeletonema dohrnii*）开展了基于同位素相对与绝对定量标记（iTRAQ，isobaric Tags for Relative and Absolute Quantitation）的蛋白质组学分析。本研究在4种不同环境条件下共检测到3369个差异丰度蛋白，并通过基因本体（Gene Ontology, GO）注释与京都基因与基因组百科全书通路（KEGG pathway）分析完成了所有蛋白的功能注释。为区分不同样本间的蛋白质组差异，本研究通过比较蛋白比值差异开展了多元统计分析（主成分分析PCA、偏最小二乘判别分析PLS-DA）。进一步针对硅藻蛋白质组开展通路富集分析后，本研究证实：在相关细胞过程中，光合作用、碳代谢及核糖体生物发生通路出现下调，进而导致氧化还原酶活性降低，并影响硅藻的细胞周期。通过偏最小二乘判别分析可变重要性投影得分（VIP score）图分析，本研究鉴定出15个可区分受试样本的蛋白质生物标志物。其中，5个蛋白/基因（rbcL、PRK、atpB、DNA结合蛋白及信号转导相关蛋白）被鉴定为关键生物标志物，其表达受温度与硅酸盐胁迫诱导，参与硅藻代谢过程。本研究结果表明，针对不同环境条件下的多氏骨条藻开展蛋白质组指纹图谱分析，可为强化海洋浮游植物蛋白质组学研究提供新的生物学信息。