Retentive Memory of Bacteria: Long-Term Regulation of Dehalorespiration in Sulfurospirillum multivorans

Abstract

The gram-negative, strictly anaerobic epsilonproteobacterium Sulfurospirillum multivorans is able to gain energy from dehalorespiration with tetrachloroethene (perchloroethylene [PCE]) as a terminal electron acceptor. The organism can also utilize fumarate as an electron acceptor. Prolonged subcultivation of S. multivorans in the absence of PCE with pyruvate as an electron donor and fumarate as an electron acceptor resulted in a decrease of PCE dehalogenase (PceA) activity. Concomitantly, the pceA transcript level equally decreased as shown by reverse transcriptase PCR. (19). The organism utilizes pyruvate, hydrogen, or formate as an electron donor. When grown with hydrogen or formate as an electron donor and PCE as an electron acceptor, ATP synthesis is coupled to reductive dechlorination via electron transport phosphorylation (dehalorespiration) (8). The key enzyme of PCE utilization that converts PCE via TCE to cis-1,2-dichloroethene (cDCE) is the PCE reductive dehalogenase (PceA). Mature PceA is a monomeric enzyme harboring one norpseudovitamin B 12 and two Fe/S clusters as cofactors (12,15). The cytoplasmic precursor of the PCE dehalogenase (pre-PceA) bears an N-terminal signal peptide of 37 amino acids, including the motif SRRXFXK, which identifies pre-PceA as a substrate of the Tat (twin arginine translocation) protein export pathway (2). Mature PceA is localized in the periplasm, as shown by freeze fracture immunogold labeling techniques (9).The pce operon comprises pceA, the PCE dehalogenase gene, and pceB, encoding a putative membrane integral protein (16). Genes for transcriptional regulation of the pceAB genes are not found in a 6-kb DNA fragment including the pce operon (GenBank accession number AF022812).The ability of reductive dechlorination by anaerobic bacteria was found in phylogenetically distant species (8). Transcriptional regulation of dehalogenase gene expression was described for the 3-chloro-4-hydroxy-phenylacetate (Cl-OHPA) dehalogenase (CprA) of the gram-positive Desulfitobacterium dehalogenans. In this organism, the enzyme was strictly regulated by the absence or presence of the substrate. When the cultures were grown with alternative electron acceptors, such as fumarate or nitrate, CprA transcription ceased within the first subcultivation and was induced within less than 30 min (21). A CRP/FNR-like transcriptional activator, CprK, encoded within the cpr operon, was shown to interact with the DNA upstream of the cpr promoter region only when Cl-OHPA was bound to the protein (18). A direct role of CprK in the induction of dehalogenase gene expression in D. dehalogenans was assumed, and a model for transcriptional regulation of cprA expression was developed (13).While detailed information is available on the control of dehalogenase gene expression in D. dehalogenans grown in the presence of chlorinated aromatic compounds, such as Cl-OHPA, a transcriptional regulation of the PCE dehalogenase genes of Desulfitobacterium species has not been described so far (23). Tsukagoshi and coworker...

The Physiological Opportunism of Desulfitobacterium hafniense Strain TCE1 towards Organohalide Respiration with Tetrachloroethene

“…Different adaptation processes for the same outcome. By following the experimental approach employed previously by John and coworkers for Sulfurospirillum multivorans (8), our study highlights a completely different mechanism by which D. hafniense strain TCE1 stopped the production of PceA in the prolonged absence of its substrate, PCE. The direct genetic environments of the pce gene cluster in strain TCE1 already suggested that pceA was strongly and constitutively expressed by the promoter embedded in the vicinal insertion sequence.…”

“…For this purpose, we used an approach inspired by a recent study on the reductive dehalogenase of Sulfurospirillum multivorans (8). Starting from a culture routinely cultivated on PCE, we transferred strain TCE1 into a medium containing fumarate and successively transferred the culture 30 times in the absence of PCE.…”

Dehalococcoides mccartyi Strain DCMB5 Respires a Broad Spectrum of Chlorinated Aromatic Compounds

“…Whether Dcmb_86 has a role in the dechlorination of PCE to TCE can only be determined by biochemical studies. So far it cannot be ruled out that unknown long-term regulatory effects keep its formation at a high level over consecutive transfers in the absence of the inducing compound, as has been reported for PceA in Sulfurospirillum multivorans (52). Two further Rdh proteins, Dcmb_ 1341 and Dcmb_1444, were indicated in the proteomes of the first and second transfer with PCE; however, the expression seems less substrate specific, because they were also detected in at least some replicates of 1,2,3-TCB-grown cells ( Fig.…”

Functional Heterologous Production of Reductive Dehalogenases from Desulfitobacterium hafniense Strains

“…Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE, 12.5%) was used to separate proteins of S. blattae crude extracts (10 g protein/lane). The immunoblot was generated as described by John et al (32). The Strep-tag-specific antibody solution (IBA, Göttingen, Germany) was diluted 3,000-fold, and the antibodies were detected via a secondary antibody coupled to alkaline phosphatase (Sigma-Aldrich, Munich, Germany).…”