Comparative amino acid sequence of fructose-1,6-bisphosphatases: identification of a region unique to the light-regulated chloroplast enzyme.
Chloroplast fructose-1,6-bisphosphatase (Fru-P2-ase) is an essential enzyme in the photosynthetic pathway of carbon dioxide fixation into sugars. The properties of the chloroplast enzyme are clearly distinct from cytosolic gluconeogenic Fru-P2-ases. Light-dependent activation by way of a ferredoxin/thioredoxin system and insensitivity to AMP inhibition are distinctive characteristics of the chloroplast enzyme. However, the chloroplast enzyme shows a high degree of amino acid sequence similarity to gluconeogenic Fru-P2-ases. Sequence data reported for a total of 285 residues (approximately 75% of the structure) of the spinach chloroplast enzyme reveals a 46% amino acid sequence identity with pig kidney Fru-P2-ase. We now report the amino acid sequence of a region consisting of 46 additional residues. This region is located near the middle of the primary structure of the enzyme and it includes a 16-residue insert not present in other Fru-P2-ases. This sequence insert has two cysteines separated by only 4 amino acid residues (Cys-Val-Val-Asn-Val-Cys), a characteristic feature of at least three other enzymes containing redox-active cysteines. It appears likely that this region of chloroplast Fru-P2-ase is involved in light-dependent activation.
Marcus
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F
Department of Biological Chemistry and Structure, University of Health Sciences, Chicago Medical School, IL 60064.
Moberly
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L
Latshaw
S P
SP
D000595:Amino Acid Sequence; D000818:Animals; D002736:Chloroplasts / Q000201:enzymology*; D002851:Chromatography, High Pressure Liquid; D006597:Fructose-Bisphosphatase / Q000032:analysis*; D008027:Light; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000032:analysis; D010449:Peptide Mapping; D014675:Vegetables
D010446:Peptide Fragments; D006597:Fructose-Bisphosphatase