Regulation of the synthesis of H 2 -forming methylenetetrahydromethanopterin dehydrogenase (Hmd) and of HmdII and HmdIII in Methanothermobacter marburgensis

Abstract

ERRATUMThe online version of the original article can be found at http://dx.

Selenium Is Involved in Regulation of Periplasmic Hydrogenase Gene Expression in Desulfovibrio vulgaris Hildenborough

“…For pyruvate-sulfate (P/S) or pyruvate (P), growth in the presence of Se led to a slightly faster growth rate but similar yield compared to Fe or Fe plus Ni conditions (data not shown). 1 Hase shows highest band intensity in H 2 /S followed by L/S, whereas it is almost not detected in L/T.…”

“…The [NiFeSe] Hase is structurally very similar to the [NiFe] Hases, with the major differences being that it has a selenocysteine as one of the ligands to the active-site Ni and the small subunit has a medial [4Fe4S] 2ϩ/ϩ cluster rather than a [3Fe4S] ϩ/0 cluster (11,36). In standard assays, the [NiFeSe] Hase displays much higher activity values than the [NiFe] 1 Hase, and it is also resistant to inactivation by oxygen (36). A comparison of the catalytic activities of the three D. vulgaris Hildenborough Hases was recently reported (36).…”

“…In the particular case of Hases, Ni is required for complete maturation of [NiFe] Hases (32), and transcriptional regulation by Ni has been shown, for example, in Bradyrhizobium japonicum (22) and in Methanothermobacter marburgensis. In the latter organism, growth in Ni-limited conditions leads to increased expression of the Ni-free Hase H 2 -forming methylenetetrahydromethanopterin dehydrogenase (Hmd) and strongly decreased expression of the [NiFe] Hase F 420 -reducing hydrogenase (Frh) (1). Both of these Hases are regulated at the transcriptional level, whereas the decreased expression of the [NiFe] methyl viologen-reducing hydrogenase (Mvh) in these conditions is due to regulation at a posttranscriptional level (34).…”

The metal‐free hydrogenase from methanogenic archaea: evidence for a bound cofactor

“…Active H 2 -forming methylene-H 4 MPT dehydrogenase (Hmd) was puri¢ed from M. marburgensis [1], from M. jannaschii and from M. kandleri [13] with speci¢c activities of 1500, 350 and 600 U/mg, respectively. M. marburgensis was grown in batch culture under nickel-limited conditions [6,19]. The cells of M. jannaschii and M. kandleri were a gift of K.O.…”

Molecular Biology of Microbial Hydrogenases

“…On the other hand, the homologous HoxBC (RH) protein in R. eutropha, which contains Ni (Pierik et al, 1998), is nearly independent of HypB . Also not clear is the mechanism by which Ni regulates H 2 ase transcription in R. leguminosarum (Brito et al, 2000), in Nostoc strains or how Hmd H 2 ase is induced and F 420 -reducing H 2 ase completely repressed in M. marburgensis, under nickel limitation (Afting et al, 2000).…”