SurR regulates hydrogen production in Pyrococcus furiosus by a sulfur-dependent redox switch

Abstract

SummaryWe present structural and biochemical evidence for a redox switch in the archaeal transcriptional regulator SurR of Pyrococcus furiosus, a hyperthermophilic anaerobe. P. furiosus produces H2 during fermentation, but undergoes a metabolic shift to produce H2S when elemental sulfur (S 0 ) becomes available. Changes in gene expression occur within minutes of S 0 addition, and the majority of these S 0 -responsive genes are regulatory targets of SurR, a key regulator involved in primary S 0 response. SurR was shown in vitro to have dual functionality, activating transcription of some of these genes, notably the hydrogenase operons, and repressing others, including a geneencoding sulfur reductase. This work demonstrates via biochemical and structural evidence that the activity of SurR is modulated by cysteine residues in a CxxC motif that constitutes a redox switch. Oxidation of the switch with S 0 inhibits sequence-specific DNA binding by SurR, leading to deactivation of genes related to H2 production and derepression of genes involved in S 0 metabolism.

Deletion Strains Reveal Metabolic Roles for Key Elemental Sulfur-Responsive Proteins in Pyrococcus furiosus

“…These enzymes, in combination with SuDH I and SuDH II, may be able to generate amounts of sulfide in NSR1 comparable to those in the parent strain. It has been shown that in the absence of S 0 , SurR activates the transcription of genes necessary for H 2 metabolism and represses that of those required for growth with S 0 (27). Addition of S 0 leads to SurR oxidation, possibly mediated by either colloidal S 0 or polysulfide, such that it is unable to bind DNA (27).…”

“…It has been shown that in the absence of S 0 , SurR activates the transcription of genes necessary for H 2 metabolism and represses that of those required for growth with S 0 (27). Addition of S 0 leads to SurR oxidation, possibly mediated by either colloidal S 0 or polysulfide, such that it is unable to bind DNA (27). Since the degree of the SurR-mediated gene regulation was up to 80% lower in the MBX1 and NSR1 deletion strains than in the parent strain (Fig.…”

“…The DNA-binding activity of SurR is modulated by a redox-dependent conformational change whereby SurR is unable to bind DNA in the presence of S 0 (27). Accordingly, the expression of the genes encoding both MBX and NSR increases and the expression of the operon encoding MBH (as well as those encoding two soluble NiFe-hydrogenases, SHI and SHII) decreases as part of the primary S 0 response (22).…”

Engineering Hydrogen Gas Production from Formate in a Hyperthermophile by Heterologous Production of an 18-Subunit Membrane-bound Complex

“…The native promoter of FHL was replaced with that of the P. furiosus Mbh operon (P mbh1 ), the transcription of which is activated by the SurR regulator during growth in the absence of S 0 , thereby allowing Mbh to catalyze H 2 evolution during sugar fermentation (27,28). A BAC vector was used to facilitate cloning of the construct for chromosomal insertion of the FHL operon ( Fig.…”

The Order Thermococcales and the Family Thermococcaceae

“…MBX is an essential component of the S 0 reduction system, although cells still reduce S 0 in the absence of Nsr (Bridger et al 2011). The metabolic shift between hydrogen and sulfur metabolism, which involves reciprocal regulation of MBH and MBX, is mediated by the transcriptional regulator SurR (Lipscomb et al 2009;Yang et al 2010). The genes encoding hydrogenases and S 0 reduction-related genes together with SurR are a unique and strictly conserved core set of genes in the Thermococcales and form a hallmark of this order (Schut et al 2012a).…”