"Required for coenzyme pyrroloquinoline quinone (PQQ)"

"Belongs to the PqqA family"

"Cofactor biosynthesis; pyrroloquinoline quinone biosynthesis."

"pyrroloquinoline quinone biosynthetic process"

"pqqA is explicitly identified as PP_0380 and as the peptide precursor for PQQ biosynthesis"

"it is a short ribosomally synthesized precursor peptide that is post-translationally modified and processed to generate the small-molecule redox cofactor pyrroloquinoline quinone (PQQ)"

"It is the **substrate/precursor peptide** from which PQQ is biosynthesized. The conserved **glutamate (E)** and **tyrosine (Y)** in the PqqA “core” provide the atoms that become cross-linked and transformed into the PQQ scaffold."

"Because PqqA is **ribosomally translated**, it is synthesized in the **cytosol**."

"PqqD binds PqqA and forms a complex with PqqE to position the PqqA core for chemistry"

"PqqE catalyzes a **regioselective C–C coupling** between the conserved glutamate and tyrosine in PqqA"

"Initial maturation occurs on the peptide precursor in the **cytosol**; mature PQQ is then used mainly by **periplasmic quinoproteins** in Gram-negative bacteria."

"The study explicitly identifies **pqqA (PP_0380)** as the peptide precursor for PQQ"