Affiliation:
1. Department of Microbiology and Biotechnology, University of Ulm, 89069 Ulm, Germany
Abstract
ABSTRACT
Corynebacterium glutamicum
recently has been shown to possess pyruvate:quinone oxidoreductase (PQO), catalyzing the oxidative decarboxylation of pyruvate to acetate and CO
2
with a quinone as the electron acceptor. Here, we analyze the expression of the
C. glutamicum pqo
gene, investigate the relevance of the PQO enzyme for growth and amino acid production, and perform phylogenetic studies. Expression analyses revealed that transcription of
pqo
is initiated 45 bp upstream of the translational start site and that it is organized in an operon together with genes encoding a putative metal-activated pyridoxal enzyme and a putative activator protein. Inactivation of the chromosomal
pqo
gene led to the absence of PQO activity; however, growth and amino acid production were not affected under either condition tested. Introduction of plasmid-bound
pqo
into a pyruvate dehydrogenase complex-negative
C. glutamicum
strain partially relieved the growth phenotype of this mutant, indicating that high PQO activity can compensate for the function of the pyruvate dehydrogenase complex. To investigate the distribution of PQO enzymes in prokaryotes and to clarify the relationship between PQO, pyruvate oxidase (POX), and acetohydroxy acid synthase enzymes, we compiled and analyzed the phylogeny of respective proteins deposited in public databases. The analyses revealed a wide distribution of PQOs among prokaryotes, corroborated the hypothesis of a common ancestry of the three enzymes, and led us to propose that the POX enzymes of
Lactobacillales
were derived from a PQO.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
28 articles.
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