Bacterial carotenoids suppressCaenorhabditis eleganssurveillance and defense of translational dysfunction

Abstract

Microbial toxins and virulence factors often target the eukaryotic translation machinery.Caenorhabditis elegans surveils for such microbial attacks by monitoring translational competence, and if a deficit is detected, particular drug detoxification and bacterial defense genes are induced. The bacteria Kocuria rhizophila has evolved countermeasures to animal translational surveillance and defense pathways. Here, we used comprehensive genetic analysis of Kocuria rhizophila to identify the bacterial genetic pathways that inhibit C. elegans translational toxin surveillance and defense. Kocuria rhizophila mutations that disrupt its ability to disable animal immunity and defense map to multiple steps in the biosynthesis of a 50-carbon bacterial carotenoid from 5 carbon precursors. Extracts of the C50 carotenoid from wild type K. rhizophila could restore this bacterial anti-immunity activity to K. rhizophila carotenoid biosynthetic mutant. Corynebacterium glutamicum, also inhibits the C. elegans translation detoxification response by producing the C50 carotenoid decaprenoxanthin, and C. glutamicum carotenoid mutants are defective in this suppression of C. elegans detoxification.Consistent with the salience of these bacterial countermeasures to animal drug responses, bacterial carotenoids sensitize C. elegans to drugs that target translation and inhibit food aversion behaviors normally induced by protein translation toxins or mutations. The surveillance and response to toxins is mediated by signaling pathways conserved across animal phylogeny, suggesting that these bacterial carotenoids may also suppress such human immune and toxin responses.

Isolation and characterization of a heavy metal- and antibiotic-tolerant novel bacterial strain from a contaminated culture plate of Chlamydomonas reinhardtii, a green micro-alga.

“…We found that the C. glutamicum (X spectrum in Figure 12B) and K. rhizophila (Z spectrum in Figure 12D) pigment absorption spectra exhibited three major absorption peaks that are representative of decaprenoxanthin absorption at 413 nm, 437 nm and 467 nm as described in the literature. [29][30][31] These three absorption peaks from C. glutamicum absorption spectrum X and K. rhizophila absorption spectrum Z very nicely overlaid against the three absorption peaks from the Clip185 absorption spectrum (Y spectrum in Figure 12B and Figure 12D). This result very strongly indicates the presence of decaprenoxanthin in Clip185.…”

“…as anti-oxidants and light harvesting pigments, photo-protection, acting as membrane stabilizers or repressors of translational surveillance and defense pathways in nematodes etc.). 29,67,68 Commercially, carotenoids are used as food colorants, animal feed supplements, cosmetics, antioxidants and other health supplements. 67,69 Pathways and related enzymes for carotenoid biosynthesis are well characterized (Figure 11).…”

“…Three maximum absorption peaks of decaprenoxanthin were monitored at 413 nm, 437 nm and 467 nm, as described for decaprenoxanthin and its glucosides in the literature. [29][30][31] C. glutamicum and K. rhizophila were used as positive controls in spectrophotometric analyses. Three replicates per strain were used in this experiment.…”

“…we extracted the yellow pigment from Clip185 (Figure 12A; Figure 12C) and performed spectrophotometric analyses to determine whether Clip185 produces decaprenoxanthin (Figure 12). As actinobacteria C. glutamicum and Kocuria rhizophila are known to produce decaprenoxanthin, 16,29 we used extracted pigments from these two bacterial strains (Figure 12A; Figure 12C) as positive controls in the spectrophotometric assays (Figure 12).…”

Isolation and characterization of a heavy metal- and antibiotic-tolerant novel bacterial strain from a contaminated culture plate of Chlamydomonas reinhardtii, a green micro-alga.

“…Three maximum absorption peaks of decaprenoxanthin were monitored at 413 nm, 437 nm and 467 nm, as described for decaprenoxanthin and its glucosides in the literature. 30 – 32 C. glutamicum and K. rhizophila were used as positive controls in spectrophotometric analyses. Three biological replicates per strain were used in this experiment.…”