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The effects of low pH on the properties of protochlorophyllide oxidoreductase and the organization of prolamellar bodies of maize (Zea mays)

Selstam, Eva; Schelin, Jenny LU ; Brain, Tony and Williams, W Patrick (2002) In European Journal of Biochemistry 269(9). p.46-2336
Abstract

Prolamellar bodies (PLB) contain two photochemically active forms of the enzyme protochlorophyllide oxidoreductase POR-PChlide640 and POR-PChlide650 (the spectral forms of POR-Chlide complexes with absorption maxima at the indicated wavelengths). Resuspension of maize PLB in media with a pH below 6.8 leads to a rapid conversion of POR-PChlide650 to POR-PChlide640 and a dramatic re-organization of the PLB membrane system. In the absence of excess NADPH, the absorption maximum of the POR complex undergoes a further shift to about 635 nm. This latter shift is reversible on the re-addition of NADPH with a half-saturation value of about 0.25 mm NADPH for POR-PChlide640 reformation. The disappearance of POR-PChlide650 and the reorganization... (More)

Prolamellar bodies (PLB) contain two photochemically active forms of the enzyme protochlorophyllide oxidoreductase POR-PChlide640 and POR-PChlide650 (the spectral forms of POR-Chlide complexes with absorption maxima at the indicated wavelengths). Resuspension of maize PLB in media with a pH below 6.8 leads to a rapid conversion of POR-PChlide650 to POR-PChlide640 and a dramatic re-organization of the PLB membrane system. In the absence of excess NADPH, the absorption maximum of the POR complex undergoes a further shift to about 635 nm. This latter shift is reversible on the re-addition of NADPH with a half-saturation value of about 0.25 mm NADPH for POR-PChlide640 reformation. The disappearance of POR-PChlide650 and the reorganization of the PLB, however, are irreversible. Restoration of low-pH treated PLB to pH 7.5 leads to a further breakdown down of the PLB membrane and no reformation of POR-PChlide650. Related spectral changes are seen in PLB aged at room temperature at pH 7.5 in NADPH-free assay medium. The reformation of POR-PChlide650 in this system is readily reversible on re-addition of NADPH with a half-saturation value about 1.0 microm. Comparison of the two sets of changes suggest a close link between the stability of the POR-PChlide650, membrane organization and NADPH binding. The low-pH driven spectral changes seen in maize PLB are shown to be accelerated by adenosine AMP, ADP and ATP. The significance of this is discussed in terms of current suggestions of the possible involvement of phosphorylation (or adenylation) in changes in the aggregational state of the POR complex.

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publishing date
type
Contribution to journal
publication status
published
keywords
Adenosine Triphosphate/pharmacology, Hydrogen-Ion Concentration, Microscopy, Electron, NADP/metabolism, Oxidoreductases/metabolism, Oxidoreductases Acting on CH-CH Group Donors, Phosphorylation, Sodium Fluoride/pharmacology, Zea mays/enzymology
in
European Journal of Biochemistry
volume
269
issue
9
pages
11 pages
publisher
Wiley-Blackwell
external identifiers
  • scopus:0036096504
ISSN
0014-2956
DOI
0.1046/j.1432-1033.2002.02897.x
language
English
LU publication?
no
id
49c59cae-7506-4567-b495-67a3fb217876
date added to LUP
2018-06-11 10:47:36
date last changed
2018-08-12 04:44:34
@article{49c59cae-7506-4567-b495-67a3fb217876,
  abstract     = {<p>Prolamellar bodies (PLB) contain two photochemically active forms of the enzyme protochlorophyllide oxidoreductase POR-PChlide640 and POR-PChlide650 (the spectral forms of POR-Chlide complexes with absorption maxima at the indicated wavelengths). Resuspension of maize PLB in media with a pH below 6.8 leads to a rapid conversion of POR-PChlide650 to POR-PChlide640 and a dramatic re-organization of the PLB membrane system. In the absence of excess NADPH, the absorption maximum of the POR complex undergoes a further shift to about 635 nm. This latter shift is reversible on the re-addition of NADPH with a half-saturation value of about 0.25 mm NADPH for POR-PChlide640 reformation. The disappearance of POR-PChlide650 and the reorganization of the PLB, however, are irreversible. Restoration of low-pH treated PLB to pH 7.5 leads to a further breakdown down of the PLB membrane and no reformation of POR-PChlide650. Related spectral changes are seen in PLB aged at room temperature at pH 7.5 in NADPH-free assay medium. The reformation of POR-PChlide650 in this system is readily reversible on re-addition of NADPH with a half-saturation value about 1.0 microm. Comparison of the two sets of changes suggest a close link between the stability of the POR-PChlide650, membrane organization and NADPH binding. The low-pH driven spectral changes seen in maize PLB are shown to be accelerated by adenosine AMP, ADP and ATP. The significance of this is discussed in terms of current suggestions of the possible involvement of phosphorylation (or adenylation) in changes in the aggregational state of the POR complex.</p>},
  author       = {Selstam, Eva and Schelin, Jenny and Brain, Tony and Williams, W Patrick},
  issn         = {0014-2956},
  keyword      = {Adenosine Triphosphate/pharmacology,Hydrogen-Ion Concentration,Microscopy, Electron,NADP/metabolism,Oxidoreductases/metabolism,Oxidoreductases Acting on CH-CH Group Donors,Phosphorylation,Sodium Fluoride/pharmacology,Zea mays/enzymology},
  language     = {eng},
  number       = {9},
  pages        = {46--2336},
  publisher    = {Wiley-Blackwell},
  series       = {European Journal of Biochemistry},
  title        = {The effects of low pH on the properties of protochlorophyllide oxidoreductase and the organization of prolamellar bodies of maize (Zea mays)},
  url          = {http://dx.doi.org/0.1046/j.1432-1033.2002.02897.x},
  volume       = {269},
  year         = {2002},
}