Biosynthesis of -Hydrogenase

Durmowicz MC, Maier RJ. 1997. Roles of HoxX and HoxA in biosynthesis of hydrogenase in Bradyrhizobium japonicum. J Bacteriol 179 3676-82. 

Reissmann S, E Hochleitner, H Wang, A Paschos, E Lottspeich, RS Glass, A Bock (2003) Taming of a poison biosynthesis of the NiFe-hydrogenase cyanide ligands. Science 299 1067-1070. 

Complementation with hypF gene from T. roseopersicina in a AhypF strain of R capsulatus was successful, a clear demonstration that a functionally active form of this Thiocapsa gene product is synthesised by the R capsulatus cells from the foreign template. The same experiment using a AhypF E. coli strain resulted in barely detectable complementation. We conclude that there must be strain dependent variations in the complementation capacity and that the most thoroughly studied bacterium, E. coli, may not be the best choice for such complementation studies of hydrogenase assembly and biosynthesis. 

Hydrogenase isoenzymes are also common among the metabolically more versatile bacteria (see Chapter 2). For instance, H2 metabolism and isoenzyme composition in enteric bacteria, including Escherichia coli and Salmonella typhimurium, appear to be differentially regulated under the two modes of anaerobic life, fermentation and anaerobic respiration (Table 3.1). Furthermore, biosynthesis of the individual isoenzymes appears to be controlled at a global level by the quality of the carbon source. 

A further gene, hypX, required for maturation of hydrogenase has been found in R. leguminosarum, B. japonicum and R. eutropha (Rey et al. 1996, Buhrke and Friedrich 1998) but does not seem to be present in E. coli. The ypX-encoded protein contains a region with sequence identity to N °-formyltetrahydrofolate-depen-dent enzymes, e.g. phosphoribosylglycinamide formyl transferase which catalyses the fourth step in purine biosynthesis. 

Maier RJ, Olson JW, Eox J. 1997. Nickel-dependent expression and maturation of hydrogenase. In Ludden PW. Burris JE, editor. Biosynthesis and function of metal clusters for enzymes the 25th Steenbock Symposinm Proceedings. Madison University of Wisconsin, p 133-42. 

We continue our attempts to gain some control over the construction of D. vulgaris bidirectional hydrogenase in E. coli not only to come to an understanding of the biosynthesis of complex Fe/S enzymes, but also to bring the candidacy of this protein for biotechnological applications within the realm of possibility. 

P-cluster of nitrogenases, the three types of metal clusters found in microbial hydrogenases, the unusual common structural features of which include CO ligands, and the Cuz cluster of microbial nitrous oxidases. The biosynthesis of some of these cofactors is discussed later in this chapter. 

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