Another Unusual Type of Citric Acid Cycle Enzyme in Helicobacter pylori : the Malate:Quinone Oxidoreductase

• DOI: 10.1128/jb.182.11.3204-3209.2000
• Publication Date: 2002-07-27T10:00:58Z
• Authors: Birgit Kather; Kerstin Stingl; Michel E. van der...; Karlheinz Altendorf; Douwe Molenaar
• Keywords: Corynebacterium glutamicum; Malate dehydrogenase

ABSTRACT The only enzyme of the citric acid cycle for which no open reading frame (ORF) was found in Helicobacter pylori genome is NAD-dependent malate dehydrogenase. Here, it shown that this organism oxidation to oxaloacetate catalyzed by a malate:quinone oxidoreductase (MQO). This flavin adenine dinucleotide-dependent membrane-associated donates electrons quinones electron transfer chain. Similar succinate dehydrogenase, part both chain and cycle. MQO activity demonstrated isolated membranes H. . encoded ORF HP0086, fact expression HP0086 sequence from plasmid induces high mqo deletion mutants Escherichia coli or Corynebacterium glutamicum Furthermore, able complement phenotype C. mutant. Interestingly, protein predicted be distantly related known postulated sequences other bacteria. presence an here previously 2-ketoglutarate:ferredoxin succinyl-coenzyme A (CoA):acetoacetyl-CoA transferase indicate possesses complete cycle, but one deviates standard textbook example three steps.