Comparison of Chloroflexus aurantiacus strain J-10-fl proteomes of cells grown chemoheterotrophically and photoheterotrophically

Abstract

Chloroflexus aurantiacus J-10-fl is a thermophilic green bacterium, a filamentous anoxygenic phototroph, and the model organism of the phylum Chloroflexi. We applied high-throughput, liquid chromatography-mass spectrometry in a global quantitative proteomics investigation of C. aurantiacus cells grown under oxic (chemoorganoheterotrophically) and anoxic (photoorganoheterotrophically) redox states. Our global analysis identified 13,524 high-confidence peptides that matched to 1,286 annotated proteins, 242 of which were either uniquely identified or significantly increased in abundance under photoheterotrophic culture condition. Fifty-four of the 242 proteins are previously characterized photosynthesis-related proteins, including chlorosome proteins, proteins involved in the bacteriochlorophyll biosynthesis, 3-hydroxypropionate (3-OHP) CO(2) fixation pathway, and components of electron transport chains. The remaining 188 proteins have not previously been reported. Of these, five proteins were found to be encoded by genes from a novel operon and observed only in photoheterotrophically grown cells. These proteins candidates may prove useful in further deciphering the phototrophic physiology of C. aurantiacus and other filamentous anoxygenic phototrophs.

‘Candidatus Thermochlorobacter aerophilum:’ an aerobic chlorophotoheterotrophic member of the phylum Chlorobi defined by metagenomics and metatranscriptomics

“…switch from oxygenic photosynthesis to respiration and then fermentation (Nold and Ward, 1996, Steunou et al, 2006, Jensen et al, 2011. Other genes in the 'night pattern' cluster included csmC, encoding another GSB-specific chlorosome envelope protein ; pucC, whose product has various roles in photosynthesis (Tichy et al, 1991;Steunou et al, 2004;Jaschke et al, 2008); and genes neighboring csmA and csmC, whose probable functioning in photosynthesis is suggested by these and other data (Cao et al, 2012;Garcia Costas et al, 2012;Supplementary Figure 2). Assuming that translation continues in 'Ca.…”

Temporal metatranscriptomic patterning in phototrophic Chloroflexi inhabiting a microbial mat in a geothermal spring

“…These proteins were hypothesized to function during phototrophic (AurA) and respiratory (AurB) electron transfer, respectively (Lee et al, 2009). Contrary to these predictions, a recent proteomic analysis of C. aurantiacus OK-70-fl revealed that peptides corresponding to AurA were more abundant in cultures grown under dark oxic conditions than when grown photoheterotrophically, while peptides from AurB showed higher abundance during photoheterotrophic growth (Cao et al, 2012). The transcript levels for the aurA and aurB genes of Chloroflexus spp.…”

“…Genomes of Chloroflexus spp. contain paralogous genes encoding the soluble electron carrier, auracyanin (McManus et al, 1992;van Driessche et al, 1999;Tsukatani et al, 2007;Cao et al 2012), and both Chloroflexus and Roseiflexus spp. contain paralogs of some of the major enzyme complexes involved in the electron transport chain, namely NADH:menaquinone oxidoreductase (Complex I; van der Meer et al, 2010;Tang et al, 2011), and Alternative Complex III (ACIII; Yanyushin et al, 2005;Gao et al, 2009).…”

“…modulate the transcriptional activity of their paralogous ACIII complexes in order to produce complexes specialized for either phototrophic or respiratory electron transfer. Regardless of the lack of in situ transcriptional evidence, a recent proteomic study of C. aurantiacus showed that peptides derived from subunits of the Cp-ACIII complex occurred in higher abundance during photoheterotrophic growth compared with levels in cells grown chemoorganoheterotrophically (Cao et al, 2012). It remains to be determined whether the abundance of the Cp and Cr proteins exhibit diel patterns, and ongoing metaproteomic work will determine if the same pattern is observed in situ.…”

“…have only one gene for auracyanin (Tsukatani et al, 2007), and its transcript levels were highest during the day. Ongoing metaproteomic characterization of this community such as the work done by Schaffert et al (2012) could indicate whether the abundance of proteins correlates with the observed transcription patterns and will enable direct comparisons to the proteomes of C. aurantiacus cells grown heterotrophically and photoheterotrophically in the laboratory (Cao et al, 2012).…”