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EM single particle analysis of the ATP-dependent BchI complex of magnesium chelatase: an AAA+ hexamer

Willows, R D; Hansson, Andreas LU ; Birch, D; Al-Karadaghi, Salam LU and Hansson, Mats LU (2004) In Journal of Structural Biology1991-01-01+01:00 146(1-2). p.227-233
Abstract
BchI, belonging to the AAA+-protein family, forms the enzyme magnesium chelatase together with BchD and BchH. This enzyme catalyses the insertion of Mg2+ into protoporphyrin IX upon ATP hydrolysis. Previous studies have indicated that BchI forms ATP-dependent complexes and it is a member of the AAA+-protein family (ATPases associated with various cellular activities) and it was suggested based on structural homology that the BchI formed hexameric complexes. AAA+-proteins are Mg2+-dependent ATPases that normally form oligomeric ring complexes in the presence of ATP. Single particle analysis of fully formed ring complexes of BchI observed by negative staining EM indicate that the BchI has strong 6- and 2-fold rotational symmetries and a... (More)
BchI, belonging to the AAA+-protein family, forms the enzyme magnesium chelatase together with BchD and BchH. This enzyme catalyses the insertion of Mg2+ into protoporphyrin IX upon ATP hydrolysis. Previous studies have indicated that BchI forms ATP-dependent complexes and it is a member of the AAA+-protein family (ATPases associated with various cellular activities) and it was suggested based on structural homology that the BchI formed hexameric complexes. AAA+-proteins are Mg2+-dependent ATPases that normally form oligomeric ring complexes in the presence of ATP. Single particle analysis of fully formed ring complexes of BchI observed by negative staining EM indicate that the BchI has strong 6- and 2-fold rotational symmetries and a weaker 4-fold rotational symmetry which are reminiscent of DNA helicase. A 2D average of the fully formed BchI–ATP ring complex is presented here from images of the complex obtained from negative staining EM. Other complexes are also observed in the EM micrographs and the class averages of these are indicative of the fragility and dynamic nature of the BchI complex which has been reported and they are suggestive of partially circular complexes with six or less protomers per particle. The resolution of the average circular complex is estimated at ~30 Å and it is similar in shape and size to an atomic resolution hexameric model of BchI rendered at 30 Å. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
AAA-proteins, ATPase, Magnesium chelatase, Chlorophyll biosynthesis
in
Journal of Structural Biology1991-01-01+01:00
volume
146
issue
1-2
pages
227 - 233
publisher
Elsevier
external identifiers
  • wos:000220548600023
  • scopus:1642265785
ISSN
1095-8657
DOI
10.1016/j.jsb.2003.11.019
language
English
LU publication?
yes
id
94f4a708-70aa-4be5-9aec-ccd2f2d64a20 (old id 126476)
date added to LUP
2007-07-09 10:39:24
date last changed
2017-07-02 04:18:05
@article{94f4a708-70aa-4be5-9aec-ccd2f2d64a20,
  abstract     = {BchI, belonging to the AAA+-protein family, forms the enzyme magnesium chelatase together with BchD and BchH. This enzyme catalyses the insertion of Mg2+ into protoporphyrin IX upon ATP hydrolysis. Previous studies have indicated that BchI forms ATP-dependent complexes and it is a member of the AAA+-protein family (ATPases associated with various cellular activities) and it was suggested based on structural homology that the BchI formed hexameric complexes. AAA+-proteins are Mg2+-dependent ATPases that normally form oligomeric ring complexes in the presence of ATP. Single particle analysis of fully formed ring complexes of BchI observed by negative staining EM indicate that the BchI has strong 6- and 2-fold rotational symmetries and a weaker 4-fold rotational symmetry which are reminiscent of DNA helicase. A 2D average of the fully formed BchI–ATP ring complex is presented here from images of the complex obtained from negative staining EM. Other complexes are also observed in the EM micrographs and the class averages of these are indicative of the fragility and dynamic nature of the BchI complex which has been reported and they are suggestive of partially circular complexes with six or less protomers per particle. The resolution of the average circular complex is estimated at ~30 Å and it is similar in shape and size to an atomic resolution hexameric model of BchI rendered at 30 Å.},
  author       = {Willows, R D and Hansson, Andreas and Birch, D and Al-Karadaghi, Salam and Hansson, Mats},
  issn         = {1095-8657},
  keyword      = {AAA-proteins,ATPase,Magnesium chelatase,Chlorophyll biosynthesis},
  language     = {eng},
  number       = {1-2},
  pages        = {227--233},
  publisher    = {Elsevier},
  series       = {Journal of Structural Biology1991-01-01+01:00},
  title        = {EM single particle analysis of the ATP-dependent BchI complex of magnesium chelatase: an AAA+ hexamer},
  url          = {http://dx.doi.org/10.1016/j.jsb.2003.11.019},
  volume       = {146},
  year         = {2004},
}