Cloning, characterization and DNA sequencing of the gene encoding the Mr 50,000 quinoprotein glucose dehydrogenase from Acinetobacter calcoaceticus

Abstract

Recently we described the cloning of the gene coding for a Mr 87,000 glucose dehydrogenase (GDH-A) from Acinetobacter calcoaceticus. In this report we describe the cloning of a gene coding for a second GDH (GDH-B) with a Mr of 50,000 from the same organism. This gene was isolated using a 20-mer synthetic oligonucleotide, derived from the N-terminal amino acid sequence of purified GDH-B as a probe to screen a genomic bank. From the DNA sequence of the gdhB gene, a protein can be derived of Mr 52,772 with a 24 amino acid signal peptide which is removed, resulting in the mature protein with a Mr 50,231. In vitro transcription-translation of the gdhB clone shows the mature and the precursor protein. The derived amino acid sequence has no obvious homology with GDH-A of A. calcoaceticus. We show that disaccharides are specific GDH-B substrates and that 2-deoxyglucose is specific for GDH-A.