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Plant Physiol Biochem. 2013 Dec;73:266-73. doi: 10.1016/j.plaphy.2013.10.008. Epub 2013 Oct 17.

Overexpression, purification and enzymatic characterization of a recombinant plastidial glucose-6-phosphate dehydrogenase from barley (Hordeum vulgare cv. Nure) roots.

Author information

1
Dipartimento di Biologia, Università di Napoli "Federico II", Via Cinthia, 80126 Naples, Italy; Université de Lorraine, Unité Mixte de Recherches 1136 Interactions Arbres Microorganismes, F-54500 Vandoeuvre-lès-Nancy, France; INRA, Unité Mixte de Recherches 1136 Interactions Arbres Microorganismes, F-54280 Champenoux, France.

Abstract

In plant cells, the plastidial glucose 6-phosphate dehydrogenase (P2-G6PDH, EC 1.1.1.49) represents one of the most important sources of NADPH. However, previous studies revealed that both native and recombinant purified P2-G6PDHs show a great instability and a rapid loss of catalytic activity. Therefore it has been difficult to describe accurately the catalytic and physico-chemical properties of these isoforms. The plastidial G6PDH encoding sequence from barley roots (Hordeum vulgare cv. Nure), devoid of a long plastidial transit peptide, was expressed as recombinant protein in Escherichia coli, either untagged or with an N-terminal his-tag. After purification from both the soluble fraction and inclusion bodies, we have explored its kinetic parameters, as well as its sensitivity to reduction. The obtained results are consistent with values determined for other P2-G6PDHs previously purified from barley roots and from other land plants. Overall, these data shed light on the catalytic mechanism of plant P2-G6PDH, summarized in a proposed model in which the sequential mechanism is very similar to the mammalian cytosolic G6PDH. This study provides a rational basis to consider the recombinant barley root P2-G6PDH as a good model for further kinetic and structural studies.

KEYWORDS:

Barley roots; G6PDH; OPPP; Plastidial isoform

PMID:
24161756
DOI:
10.1016/j.plaphy.2013.10.008
[Indexed for MEDLINE]

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