Pqq-dependent methanol dehydrogenases: Rare-earth elements make a difference
In: Applied Microbiology and Biotechnology, Jg. 98 (2014), S. 6163-6183
Online
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Zugriff:
Methanol dehydrogenase (MDH) catalyzes the first step in methanol use by methylotrophic bacteria and the second step in methane conversion by methanotrophs. Gram-negative bacteria possess an MDH with pyrroloquinoline quinone (PQQ) as its catalytic center. This MDH belongs to the broad class of eight-bladed β propeller quinoproteins, which comprise a range of other alcohol and aldehyde dehydrogenases. A well-investigated MDH is the heterotetrameric MxaFI-MDH, which is composed of two large catalytic subunits (MxaF) and two small subunits (MxaI). MxaFI-MDHs bind calcium as a cofactor that assists PQQ in catalysis. Genomic analyses indicated the existence of another MDH distantly related to the MxaFI-MDHs. Recently, several of these so-called XoxF-MDHs have been isolated. XoxF-MDHs described thus far are homodimeric proteins lacking the small subunit and possess a rare-earth element (REE) instead of calcium. The presence of such REE may confer XoxF-MDHs a superior catalytic efficiency. Moreover, XoxF-MDHs are able to oxidize methanol to formate, rather than to formaldehyde as MxaFI-MDHs do. While structures of MxaFI- and XoxF-MDH are conserved, also regarding the binding of PQQ, the accommodation of a REE requires the presence of a specific aspartate residue near the catalytic site. XoxF-MDHs containing such REE-binding motif are abundantly present in genomes of methylotrophic and methanotrophic microorganisms and also in organisms that hitherto are not known for such lifestyle. Moreover, sequence analyses suggest that XoxF-MDHs represent only a small part of putative REE-containing quinoproteins, together covering an unexploited potential of metabolic functions.
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Pqq-dependent methanol dehydrogenases: Rare-earth elements make a difference
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Autor/in / Beteiligte Person: | Reimann, Joachim ; Pol, Arjan ; Huub J. M. Op den Camp ; Keltjens, Jan T. |
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Zeitschrift: | Applied Microbiology and Biotechnology, Jg. 98 (2014), S. 6163-6183 |
Veröffentlichung: | 2014 |
Medientyp: | unknown |
ISSN: | 0175-7598 (print) |
DOI: | 10.1007/s00253-014-5766-8 |
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