Adenosine 5′-triphosphate stimulation of the activity of a partially purified phytoene synthetase complex

The photoregulation of carotenoid biosynthesis in Aspergillus giganteus mut. alba

“…A partially purified phytoene complex (MV 200,000), able to convert IPP to phytoene, has been isolated from tomato fruit plastids (Maudinas et al, 1975(Maudinas et al, , 1977.…”

Phytoene synthase

“…Application of environmental stress results in increased steady-state mRNA level, light-induced expression of the gene may be under photosynthetic control [19]) [4,9,14,15,18,19] P prephytoene diphosphate + diphosphate Substrates and products S geranylgeranyl diphosphate + geranylgeranyl diphosphate <1-14> (<3, 5, 7, 9>, the same enzyme catalyzes two consecutive reactions: 1. the synthesis of prephytoene diphosphate and 2. the synthesis of phytoene [3,8,11,15]) (Reversibility: ? <1-14> ) [1-22] P prephytoene diphosphate + diphosphate <1, 2, 3> [1,2,3,4] S prephytoene diphosphate <3, 5, 7, 9> (<3, 5, 7, 9>, the same enzyme catalyzes two consecutive reactions: 1. the synthesis of prephytoene diphosphate and 2. the synthesis of phytoene [3,8,11,15]; <7>, the phytoene formed in vitro is present in both a 15-cis and all-trans isomeric configuration [11]) (Reversibility: ? <3, 5, 7, 9> [3,8,11,15]) [3,8,11,15] P phytoene + diphosphate <3, 9> (<9>, 15,15'-Z-phytoene is the sole product [15]) [3,15] Inhibitors ADP <1> [16] AMP <1> [16] CGA 103586 <12, 13, 14> [22] GTP <1> [16] Mn 2+ <1> (<1>, above 2 mM [16]) [16] NADP + <1> [16] NADPH <1> [6,…”

“…<1-14> ) [1-22] P prephytoene diphosphate + diphosphate <1, 2, 3> [1,2,3,4] S prephytoene diphosphate <3, 5, 7, 9> (<3, 5, 7, 9>, the same enzyme catalyzes two consecutive reactions: 1. the synthesis of prephytoene diphosphate and 2. the synthesis of phytoene [3,8,11,15]; <7>, the phytoene formed in vitro is present in both a 15-cis and all-trans isomeric configuration [11]) (Reversibility: ? <3, 5, 7, 9> [3,8,11,15]) [3,8,11,15] P phytoene + diphosphate <3, 9> (<9>, 15,15'-Z-phytoene is the sole product [15]) [3,15] Inhibitors ADP <1> [16] AMP <1> [16] CGA 103586 <12, 13, 14> [22] GTP <1> [16] Mn 2+ <1> (<1>, above 2 mM [16]) [16] NADP + <1> [16] NADPH <1> [6,16] NEM <1> [5] b-carotene <1> [16] chlorophyll <1> [16] fructose <8> [13] iodoacetamide <1> [5] p-hydroxymercuribenzoate <1> [5] phosphate <1, 7> [11,16] squalestatin <1, 7> (<7>, IC50: 0.015 mM [11]) [11,16] Cofactors/prosthetic groups ATP <1, 7> (<1>, 1.3 mM, 7fold stimulation, most probably an allosteric effector…”

“…<3, 5, 7, 9> [3,8,11,15]) [3,8,11,15] P phytoene + diphosphate <3, 9> (<9>, 15,15'-Z-phytoene is the sole product [15]) [3,15] Inhibitors ADP <1> [16] AMP <1> [16] CGA 103586 <12, 13, 14> [22] GTP <1> [16] Mn 2+ <1> (<1>, above 2 mM [16]) [16] NADP + <1> [16] NADPH <1> [6,16] NEM <1> [5] b-carotene <1> [16] chlorophyll <1> [16] fructose <8> [13] iodoacetamide <1> [5] p-hydroxymercuribenzoate <1> [5] phosphate <1, 7> [11,16] squalestatin <1, 7> (<7>, IC50: 0.015 mM [11]) [11,16] Cofactors/prosthetic groups ATP <1, 7> (<1>, 1.3 mM, 7fold stimulation, most probably an allosteric effector [1]; <1>, stimulates [5]; <7>, required [11]) [1,5,11] Activating compounds ATP <1, 7> (<1>, Mn 2+ and ATP are essential for catalytic activity, the effect is stoichiometric from 0.5-2 mM. K m for ATP is 2.0 mM [16]; <1>, 1.3 mM, 7fold stimulation, most probably an allosteric effector [1]; <1>, stimulates [5]; <7>, required [11])…”

“…Subsequent illumination of dark-grown and/or in far-red light seedlings with white light causes the decay of these structures and a topological relocalization of PSY to developing thylakoids which results in its enzymatic activation. The light-dependent mechanism of regulation may contribute to ensuring a spatially and temporally coordinated increase in both carotenoid and chlorophyll contents [17]) [17] Metals, ions Mg 2+ <1, 7, 8> (<1>, required [5]; <7>, Mn 2+ or Mg 2+ required [11]; <8>, stimulatory in presence of Mn 2+ [13]) [5,11,13] Mn 2+ <1, 3, 7, 8, 9> (<1,9>, required [1,15]; <3>, absolute requirement for Mn 2+ , half-maximal activity at 0.2 mM. No other divalent cation can substitute efficiently for Mn 2+ [3]; <7>, Mn 2+ or Mg 2+ required [11]; <8>, absolute requirement, optimum at 1 mM [13]; <9>, maximal activity at 0.25 mM [15]; <1>, Mn 2+ and ATP in combination are essential for catalytic activity, the effect is stoichiometric from 0.5-2.0 mM.…”