A Comparative Quantitative Proteomic Study Identifies New Proteins Relevant for Sulfur Oxidation in the Purple Sulfur Bacterium Allochromatium vinosum

Abstract

bIn the present study, we compared the proteome response of Allochromatium vinosum when growing photoautotrophically in the presence of sulfide, thiosulfate, and elemental sulfur with the proteome response when the organism was growing photoheterotrophically on malate. Applying tandem mass tag analysis as well as two-dimensional (2D) PAGE, we detected 1,955 of the 3,302 predicted proteins by identification of at least two peptides (59.2%) and quantified 1,848 of the identified proteins. Altered relative protein amounts (>1.5-fold) were observed for 385 proteins, corresponding to 20.8% of the quantified A. vinosum proteome. A significant number of the proteins exhibiting strongly enhanced relative protein levels in the presence of reduced sulfur compounds are well documented essential players during oxidative sulfur metabolism, e.g., the dissimilatory sulfite reductase DsrAB. Changes in protein levels generally matched those observed for the respective relative mRNA levels in a previous study and allowed identification of new genes/proteins participating in oxidative sulfur metabolism. One gene cluster (hyd; Alvin_2036-Alvin_2040) and one hypothetical protein (Alvin_2107) exhibiting strong responses on both the transcriptome and proteome levels were chosen for gene inactivation and phenotypic analyses of the respective mutant strains, which verified the importance of the so-called Isp hydrogenase supercomplex for efficient oxidation of sulfide and a crucial role of Alvin_2107 for the oxidation of sulfur stored in sulfur globules to sulfite. In addition, we analyzed the sulfur globule proteome and identified a new sulfur globule protein (SgpD; Alvin_2515).

New Proteins Involved in Sulfur Trafficking in the Cytoplasm of Allochromatium vinosum

“…Its abundance is comparable with that for proteins involved in central carbon and energy metabolism as well as in photosynthesis. TusA even outnumbers the most prominent proteins of the Dsr system, DsrC, and DsrAB (40). Taken together, these observations strongly support the idea that A. vinosum TusA is not restricted to biosynthesis of sulfurcontaining co-factors.…”

“…2). Further hints toward the function of TusA come from proteomic data (40). TusA is one of the major proteins in A. vinosum cells grown on reduced sulfur compounds.…”

Geochemically distinct carbon isotope distributions in Allochromatium vinosum DSM 180T grown photoautotrophically and photoheterotrophically

“…Preferential expression of rbcAB during autotrophy also was observed by Weissgerber, Sylvester, et al. (), but they were unable to detect the products of rbcSL during growth on malate, while here we were able to detect low‐level rbcSL expression during growth on acetate. Measurable Rubisco in the heterotrophic culture is consistent with its use in recycling intracellular CO 2 or for CO 2 fixation at the low background concentration of the growth medium.…”

“…During photolithoautotrophic growth, H 2 S and other reduced sulfur species serve as electron donors for CO 2 fixation using Rubisco form IA (Viale, Kobayashi, & Akazawa, ; Weissgerber et al., ). During photoorganoheterotrophic growth, the cells use acetate as both the carbon substrate and the electron donor (Weissgerber, Sylvester, et al., ; Weissgerber, Watanabe, et al., ). The measured δ 13 C values of bulk biomass reflect the isotope fractionations associated with these processes, relative to the initial substrates.…”

A Sulfur Oxygenase from the Haloalkaliphilic Bacterium Thioalkalivibrio paradoxus with Atypically Low Reductase Activity

“…Both SOR and PDO might then oxidize the transiently formed sulfur from the globules upon depletion of the primary substrate. A homolog of Alvin_2107 was also found, which is essential for the oxidation of sulfur stored in sulfur globules of Allochromatium vinosum (see Table S2 in the supplemental material) (26).…”