|Gene:||pqqA||Accession Number: G-11752 (MetaCyc)|
Synonyms: PQQ biosynthesis protein A
Species: Klebsiella pneumoniae
PqqA is a small peptide that provides the precursor for the biosynthesis of the cofactor pyrroloquinoline quinone. The protein contains the sequence motif -E-X-X-X-Y-, that is, an L-glutamate and an L-tyrosine separated by three amino acid residues. The Glutamate and tyrosine residues form a C-C bond at C9-C9a (catalyzed by PqqE), and then cleaved from the PqqA peptide and processed into the mature PQQ molecule.
The pqqA gene of Klebsiella pneumoniae was cloned and expressed in Escherichia coli, and shown to be produced at a much higher level (about 20 fold) than the enzymes that are involved in the pathway [Velterop95]. When the full pqq operon was cloned and expressed in Escherichia coli, the host organism was able to produce pyrroloquinoline quinone. Omission of the pqqA gene abolished PQQ production.
Gene Citations: [Meulenberg92]
Molecular Weight of Polypeptide: 2.764 kD (from nucleotide sequence), 2.7 kD (experimental) [Velterop95 ]
Unification Links: UniProt:P27503
Reactions known to consume the compound:
Velterop95: Velterop JS, Sellink E, Meulenberg JJ, David S, Bulder I, Postma PW (1995). "Synthesis of pyrroloquinoline quinone in vivo and in vitro and detection of an intermediate in the biosynthetic pathway." J Bacteriol 177(17);5088-98. PMID: 7665488
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