AUTHOR=Nardella Caterina , Boi Dalila , di Salvo Martino L. , Barile Anna , Stetefeld Jörg , Tramonti Angela , Contestabile Roberto TITLE=Isolation of a Complex Formed Between Acinetobacter baumannii HemA and HemL, Key Enzymes of Tetrapyrroles Biosynthesis JOURNAL=Frontiers in Molecular Biosciences VOLUME=6 YEAR=2019 URL=https://www.frontiersin.org/journals/molecular-biosciences/articles/10.3389/fmolb.2019.00006 DOI=10.3389/fmolb.2019.00006 ISSN=2296-889X ABSTRACT=
Plants, algae and most bacteria synthesize 5-aminolevulinic acid (ALA), the universal precursor of tetrapyrroles such as heme, chlorophyll and coenzyme B12, by a two-step transformation involving the NADPH-dependent glutamyl-tRNA reductase (HemA), which reduces tRNA-bound glutamate to glutamate-1-semialdehyde (GSA), and the pyridoxamine 5′-phosphate-dependent glutamate-1-semialdehyde-2,1-aminomutase (HemL), responsible for the isomerization of GSA into ALA. Since GSA is a very unstable compound at pH values around neutrality, the formation of a HemA-HemL complex has been proposed to occur, allowing for direct channeling of this intermediate from HemA to HemL. Experimental evidence of the formation of this complex has been obtained with the enzymes from