Proteomic Analysis of Hydrogen Photoproduction in Sulfur-Deprived Chlamydomonas Cells

Abstract

The green alga Chlamydomonas reinhardtii is a model organism to study H(2) metabolism in photosynthetic eukaryotes. To understand the molecular mechanism of H(2) metabolism, we used 2-DE coupled with MALDI-TOF and MALDI-TOF/TOF-MS to investigate proteomic changes of Chlamydomonas cells that undergo sulfur-depleted H(2) photoproduction process. In this report, we obtained 2-D PAGE soluble protein profiles of Chlamydomonas at three time points representing different phases leading to H(2) production. We found over 105 Coomassie-stained protein spots, corresponding to 82 unique gene products, changed in abundance throughout the process. Major changes included photosynthetic machinery, protein biosynthetic apparatus, molecular chaperones, and 20S proteasomal components. A number of proteins related to sulfate, nitrogen and acetate assimilation, and antioxidative reactions were also changed significantly. Other proteins showing alteration during the sulfur-depleted H(2) photoproduction process were proteins involved in cell wall and flagella metabolisms. In addition, among these differentially expressed proteins, 11 were found to be predicted proteins without functional annotation in the Chlamydomonas genome database. The results of this proteomic analysis provide new insight into molecular basis of H(2) photoproduction in Chlamydomonas under sulfur depletion.

Multiple regulatory mechanisms in the chloroplast of green algae: relation to hydrogen production

“…Recent developments in ''omics'' technologies, including transcriptomics, proteomics, and metabolomics, have revealed new details of C. reinhardtii responses on nitrogen and sulfur depletions (Nguyen et al 2008;Matthew et al 2009;González-Ballester et al 2010;Chen et al 2010;Schmollinger et al 2014;Juergens et al 2015). In general, nutrient deficiency induces repression of most transcripts and proteins involved in the Calvin-Benson cycle, lightharvesting, photosynthetic electron transport, and tricarboxylic acid cycle, whereas those involved in the pentose phosphate pathway and fermentative metabolism, including hydrogen evolution, are enhanced.…”

“…The levels of inactivation of photosynthetic protein complexes, including Rubisco, PSII, PSI, and cytb 6 f, as well as the chloroplast ATP synthase are different in S-and N-deprived C. reinhardtii. Thus, S deficiency is characterized by predominant degradation of Rubisco and PSII complexes, and remodeling from LET to CET, whereas cytb 6 f, PSI, and the chloroplast ATP synthase suffer more in the absence of N (Wykoff et al 1998;Chen et al 2010;Schmollinger et al 2014). These peculiar responses of photosynthesis imply the involvement of nutrient-specific regulation and adaptation mechanisms.…”

“…During the last decade, significant amount of information became available on complex metabolic responses to macronutrient deficiency stress, anaerobic metabolism, and regulation of photosynthetic machinery in C. reinhardtii (Nguyen et al 2008;Matthew et al 2009;Peltier et al 2010;González-Ballester et al 2010;Chen et al 2010;Cardol et al 2011;Catalanotti et al 2013;Schmollinger et al 2014;Yang et al 2015;Juergens et al 2015). In the present review, we summarize this information to describe a complex of regulatory mechanisms induced in response to nutrient (nitrogen, sulfur, phosphorus) deficiency under aerobic and anoxic conditions in the light in the chloroplast of C. reinhardtii.…”

Relevance of nutrient media composition for hydrogen production in Chlamydomonas

“…Sulfur (S) deficiency is the most employed and studied strategy to sustain H 2 production in Chlamydomonas since Melis et al (2000) reported that Chlamydomonas cultures were capable of producing H 2 in medium devoid of S. S deficiency has a very broad impact in cell metabolism (Bolling and Fiehn 2005;Timmins et al 2009;Chen et al 2010;Gonzalez-Ballester et al 2010;Toepel et al 2013). Among other consequences, PSII centers undergo a rapid degradation and electron flow is severely inhibited at the PSII level, whereas PSI activity is essentially unchanged in S-starved cells Melis et al 2000;.…”

“…This alga has become a model organism due to its sequenced genome, the genetic tools, and the wealth of information available (Merchant et al 2007;Harris and Witman 2008). Multiple ''omics'' studies under different conditions have been published, which renders Chlamydomonas even more compelling as a model organism for biofuel studies in general and H 2 in particular (Miura et al 2004;Bolling and Fiehn 2005;Merchant et al 2007;Mus et al 2007;May et al 2008;Matthew et al 2009;Chen et al 2010;Doebbe et al 2010;Gonzalez-Ballester et al 2010;Terashima et al 2010;Castruita et al 2011;Subramanian et al 2014). Moreover, Chlamydomonas is able to grow heterotrophically using acetate as sole carbon source and also possesses a very versatile fermentative metabolism (Mus et al 2007;Dubini et al 2009;Catalanotti et al 2012;Magneschi et al 2012;Yang et al 2014) which gives this alga the potential for producing biofuels under autotrophic or heterotrophic conditions.…”