Structure of the Cyanobacterial Magnesium Chelatase H Subunit Determined by Single Particle Reconstruction and Small-angle X-ray Scattering

Research output: Contribution to journalArticle

Standard

Structure of the Cyanobacterial Magnesium Chelatase H Subunit Determined by Single Particle Reconstruction and Small-angle X-ray Scattering. / Qian, Pu; Marklew, Christopher J.; Viney, Joanne; Davison, Paul A.; Brindley, Amanda A.; Söderberg, Christopher; Al-Karadaghi, Salam; Bullough, Per A.; Grossmann, J. Guenter; Hunter, C. Neil.

In: Journal of Biological Chemistry, Vol. 287, No. 7, 2012, p. 4946-4956.

Research output: Contribution to journalArticle

Harvard

APA

CBE

MLA

Vancouver

Author

Qian, Pu ; Marklew, Christopher J. ; Viney, Joanne ; Davison, Paul A. ; Brindley, Amanda A. ; Söderberg, Christopher ; Al-Karadaghi, Salam ; Bullough, Per A. ; Grossmann, J. Guenter ; Hunter, C. Neil. / Structure of the Cyanobacterial Magnesium Chelatase H Subunit Determined by Single Particle Reconstruction and Small-angle X-ray Scattering. In: Journal of Biological Chemistry. 2012 ; Vol. 287, No. 7. pp. 4946-4956.

RIS

TY - JOUR

T1 - Structure of the Cyanobacterial Magnesium Chelatase H Subunit Determined by Single Particle Reconstruction and Small-angle X-ray Scattering

AU - Qian, Pu

AU - Marklew, Christopher J.

AU - Viney, Joanne

AU - Davison, Paul A.

AU - Brindley, Amanda A.

AU - Söderberg, Christopher

AU - Al-Karadaghi, Salam

AU - Bullough, Per A.

AU - Grossmann, J. Guenter

AU - Hunter, C. Neil

PY - 2012

Y1 - 2012

N2 - The biosynthesis of chlorophyll, an essential cofactor for photosynthesis, requires the ATP-dependent insertion of Mg2+ into protoporphyrin IX catalyzed by the multisubunit enzyme magnesium chelatase. This enzyme complex consists of the I subunit, an ATPase that forms a complex with the D subunit, and an H subunit that binds both the protoporphyrin substrate and the magnesium protoporphyrin product. In this study we used electron microscopy and small-angle x-ray scattering to investigate the structure of the magnesium chelatase H subunit, ChlH, from the thermophilic cyanobacterium Thermosynechococcus elongatus. Single particle reconstruction of negatively stained apo-ChlH and Chl-porphyrin proteins was used to reconstitute three-dimensional structures to a resolution of similar to 30 angstrom. ChlH is a large, 148-kDa protein of 1326 residues, forming a cage-like assembly comprising the majority of the structure, attached to a globular N-terminal domain of similar to 16 kDa by a narrow linker region. This N-terminal domain is adjacent to a 5 nm-diameter opening in the structure that allows access to a cavity. Small-angle x-ray scattering analysis of ChlH, performed on soluble, catalytically active ChlH, verifies the presence of two domains and their relative sizes. Our results provide a basis for the multiple regulatory and catalytic functions of ChlH of oxygenic photosynthetic organisms and for a chaperoning function that sequesters the enzyme-bound magnesium protoporphyrin product prior to its delivery to the next enzyme in the chlorophyll biosynthetic pathway, magnesium protoporphyrin methyltransferase.

AB - The biosynthesis of chlorophyll, an essential cofactor for photosynthesis, requires the ATP-dependent insertion of Mg2+ into protoporphyrin IX catalyzed by the multisubunit enzyme magnesium chelatase. This enzyme complex consists of the I subunit, an ATPase that forms a complex with the D subunit, and an H subunit that binds both the protoporphyrin substrate and the magnesium protoporphyrin product. In this study we used electron microscopy and small-angle x-ray scattering to investigate the structure of the magnesium chelatase H subunit, ChlH, from the thermophilic cyanobacterium Thermosynechococcus elongatus. Single particle reconstruction of negatively stained apo-ChlH and Chl-porphyrin proteins was used to reconstitute three-dimensional structures to a resolution of similar to 30 angstrom. ChlH is a large, 148-kDa protein of 1326 residues, forming a cage-like assembly comprising the majority of the structure, attached to a globular N-terminal domain of similar to 16 kDa by a narrow linker region. This N-terminal domain is adjacent to a 5 nm-diameter opening in the structure that allows access to a cavity. Small-angle x-ray scattering analysis of ChlH, performed on soluble, catalytically active ChlH, verifies the presence of two domains and their relative sizes. Our results provide a basis for the multiple regulatory and catalytic functions of ChlH of oxygenic photosynthetic organisms and for a chaperoning function that sequesters the enzyme-bound magnesium protoporphyrin product prior to its delivery to the next enzyme in the chlorophyll biosynthetic pathway, magnesium protoporphyrin methyltransferase.

U2 - 10.1074/jbc.M111.308239

DO - 10.1074/jbc.M111.308239

M3 - Article

C2 - 22179610

VL - 287

SP - 4946

EP - 4956

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 1083-351X

IS - 7

ER -