Anaerobiosis, formate, nitrate, and pyrA are involved in the regulation of formate hydrogenlyase in Salmonella typhimurium

Abstract

Three groups of mutants defective in the fermentative production of gas were isolated from Salmonella typhimurium LT2 subjected to transposition mutagenesis with Mu d(Apr lac). One group consisted of strains which lacked hydrogenase. The mutation site for this group was located in the vicinity of the known hyd gene. A second group consisted of mutants which lacked the formate dehyrogenase associated with hydrogenase. The mutation site was located in four of them. It was not in the vicinity of the previously described fhlD gene but was instead located at 93 min on the Salmonella map. The third mutant group, which consisted of strains that produced gas in triple sugar iron agar but not in nutrient agar supplemented with glucose, appeared to be pyrA mutants. The insertion site was located in the vicinity of pyrA , and they required arginine and pyrimidines for growth. Expression of the lac operon in the hyd mutants was induced by anaerobiosis. It was only slightly increased by the addition of formate under anaerobic conditions and slightly decreased by the addition of nitrate. Nitrate had no effect in an hyd ::Mu d strain that also carried a chlC::Tn10 insertion. Full expression of the lac operon in the fhl mutants required both formate and anaerobic conditions. The presence of nitrate in addition to formate resulted in activities about half those obtained in its absence, even in the fhl ::Mu d chlC::Tn10 double mutant. In the absence of formate, nitrate reduced expression only in the fhl ::Mu d single mutants. Expression of the lac operon among the pyrA mutants was repressed by arginine and cytosine and also by anaerobiosis. An explanation for the involvement of pyrA in aerobic and anaerobic energy metabolism is proposed.

Nitrate respiration in relation to facultative metabolism in enterobacteria.

“…A different simple explanation may be found in the fact that purified formate dehydrogenase-N shows a low but significant activity with viologen dyes as electron acceptors (97). Thus, the specificity of formate dehydrogenase-N, at least, is not absolute, and this low activity with viologen may contribute to the membrane-bound activity ascribed to formate dehydrogenase-H (25). Indeed, the third class of anaerogenic variant studied by Gest and Peck (see above) retains a low level of benzyl viologen-formate dehydrogenase activity (109).…”

“…This mutant was isolated from a collection of Mu dl insertion mutants in which P-galactosidase synthesis is induced by anaerobiosis. fdhF is the structural gene for the formate dehydrogenase-H 80-kDa selenopolypeptide (75,305 formate-hydrogen lyase mutants (25). The mutations, designated fhl, are also linked to mel and probably affect the Salmonella gene homologous to fdhF.…”

The CO and CN− ligands to the active site Fe in [NiFe]‐hydrogenase of Escherichia coli have different metabolic origins

“…Recent work has identified six hyp genes, hypA-F (hyp for hydrogen pleiotropy), involved in the biosynthesis of the active site of the three [NiFe]-hydrogenases in E. coli [1,5,6]. In addition, E. coli mutants with lesions in the carAB operon, encoding carbamoyl phosphate synthase, are devoid of hydrogenase activity [7,8], indicating that carbamoyl phosphate is also necessary for active site biosynthesis. A series of in vitro studies carried out with the hypC, D, E and F gene products revealed that HypE and HypF interact to generate from carbamoyl phosphate a HypE-bound thiocyanate intermediate, which was proposed to transfer the CN À group, by an unknown mechanism, to an Fe atom in the HypCD complex [9][10][11].…”

Metabolically engineered bacteria for producing hydrogen via fermentation

“…Formate hydrogen lyase activity has been found in various bacteria such as Salmonella typhimurium (Chippaux et al. , 1977; Barrett et al ., 1984), Klebsiella pneumoniae (Steuber et al ., 1999), Rhodospirillum rubrum (Schön and Voelskow, 1976); (Voelskow and Schön, 1980), Methanobacterium formicicum (Baron and Ferry, 1989), E. coli , and many other coli‐aerogenes bacteria (Peck and Gest, 1957); however, the FHL complex of E. coli is the most studied and was discovered in 1931 (Stephenson and Stickland, 1931). The FHL system of E. coli is briefly reviewed here and more detailed information can be found in other reviews (Sawers, 1994; Sawers, 2005).…”