Label-free Quantitative Proteomics Analysis of Etiolated Maize Seedling Leaves during Greening

Abstract

To better understand light regulation of C 4 plant maize development, we investigated dynamic proteomic differences between green seedlings (control), etiolated seedlings, and etiolated seedlings illuminated for 6 or 12 h using a label-free quantitative proteomics approach based on nanoscale ultraperformance liquid chromatography-ESI-MS E . Among more than 400 proteins identified, 73 were significantly altered during etiolated maize seedling greening. Of these 73 proteins, 25 were identified as membrane proteins that seldom had been identified with two-dimensional electrophoresis methods, indicating the power of our label-free method for membrane protein identification; 31 were related to light reactions of chlorophyll biosynthesis, photosynthesis, and photosynthetic carbon assimilation. The expression of photosystem II subunits was highly sensitive to light; most of them were not identified in etiolated maize seedlings but drastically increased upon light exposure, indicating that the complex process of biogenesis of the photosynthetic apparatus correlates with the transition from a dark-grown to a light-grown morphology. However, transcriptional analysis indicated that most transcripts encoding these proteins were not regulated by light. In contrast, the levels of mRNAs and proteins for enzymes involved in carbon assimilation were tightly regulated by light. Additionally phosphoenolpyruvate carboxykinase, the key enzyme of the phosphoenolpyruvate carboxykinase C 4 pathway, was more tightly regulated by light than the key enzymes of the NADP-malic enzyme C 4 pathway. Furthermore phosphoenolpyruvate carboxylase 1C, which was originally reported to be specifically expressed in roots, was also identified in this study; expression of this enzyme was more sensitive to light than its isoforms. Taken together, these results represent a comprehensive dynamic protein profile and light-regulated network of C 4 plants for etiolated seedling greening and provide a basis for further study of the mechanism of gene function and regulation in light-induced development of C 4 plants.

Biogenesis of thylakoid networks in angiosperms: knowns and unknowns

“…Whole etioplasts, usually as the starting point in greening experiments, were also subjected to proteomic analyses in maize (Lonosky et al 2004;Shen et al 2009), rice (Kleffmann et al 2007;von Zychlinski et al 2005) and pea (Kanervo et al 2008). Notably, amongst the most abundant protein complexes in pea etioplasts were (again) ATP synthase and the ATP-dependent proteases Clp and FtsH (Kanervo et al 2008).…”

Label-Free Quantitative Proteomics Analysis of Cotton Leaf Response to Nitric Oxide

“…29 The parameters of the nanoscale LC separation are outlined. An ethylene bridged hybrid C 18 1.7 μm, 75 μm  250 mm, analytical reverse-phased column (Waters, Manchester, U.K.) was used.…”

Large-scale analysis of phosphorylated proteins in maize leaf

“…The protein extraction method used here is the method we developed previously (Shen et al 2009). Leaves under normal light conditions were harvested and ground in liquid nitrogen.…”

“…Maize (Zea mays L.) is one of the most important cereal crops and a model for the study of genetics, evolution, and domestication (Wei et al 2007). Although numerous proteomics studies over the past few years have focused on various organs, tissues, cells, or organelles, comparative proteomics experiments have also led to the identiWcation of proteins that change in abundance in various developmental or physiological contexts in maize (Lonosky et al 2004;Majeran et al 2005;Sauer et al 2006;Shen et al 2009). A few other large-scale studies on phosphorylated proteins have been reported in maize.…”