When size is important: Accommodation of magnesium in a calcium binding regulatory domain

A. Malmendal, J. Evenäs, E. Thulin, G.P. Gippert, T. Drakenberg, S. Forsén

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

Resumé

The accommodation of Mg2+ in the N-terminal domain of calmodulin was followed through amide 1H and 15N chemical shifts and line widths in heteronuclear single-quantum coherence spectroscopy NMR spectra. Mg2+ binds sequentially to the two Ca2+-binding loops in this domain, with affinities such that nearly half of the loops would be occupied by Mg2+ in resting eukaryotic cells. Mg2+ binding seems to occur without ligation to the residue in the 12th loop position, previously proven largely responsible for the major rearrangements induced by binding of the larger Ca2+. Consequently, smaller Mg2+-induced structural changes are indicated throughout the protein. The two Ca2+-binding loops have different Mg2+ binding characteristics. Ligands in the N-terminal loop I are better positioned for cation binding, resulting in higher affinity and slower binding kinetics compared with the C-terminal loop II (k(off) = 380 \ 40 s-1 compared with 10,000 s-1 at 25 \C). The Mg2+-saturated loop II undergoes conformational exchange on the 100-$s time scale. Available data suggest that this exchange occurs between a conformation providing a ligand geometry optimized for Mg2+ binding and a conformation more similar to that of the empty loop.
OriginalsprogEngelsk
TidsskriftJournal of Biological Chemistry
Vol/bind273
Udgave nummer44
ISSN0021-9258
DOI
StatusUdgivet - 1998

Citer dette

Malmendal, A. ; Evenäs, J. ; Thulin, E. ; Gippert, G.P. ; Drakenberg, T. ; Forsén, S. / When size is important: Accommodation of magnesium in a calcium binding regulatory domain. I: Journal of Biological Chemistry. 1998 ; Bind 273, Nr. 44.
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title = "When size is important: Accommodation of magnesium in a calcium binding regulatory domain",
abstract = "The accommodation of Mg2+ in the N-terminal domain of calmodulin was followed through amide 1H and 15N chemical shifts and line widths in heteronuclear single-quantum coherence spectroscopy NMR spectra. Mg2+ binds sequentially to the two Ca2+-binding loops in this domain, with affinities such that nearly half of the loops would be occupied by Mg2+ in resting eukaryotic cells. Mg2+ binding seems to occur without ligation to the residue in the 12th loop position, previously proven largely responsible for the major rearrangements induced by binding of the larger Ca2+. Consequently, smaller Mg2+-induced structural changes are indicated throughout the protein. The two Ca2+-binding loops have different Mg2+ binding characteristics. Ligands in the N-terminal loop I are better positioned for cation binding, resulting in higher affinity and slower binding kinetics compared with the C-terminal loop II (k(off) = 380 \ 40 s-1 compared with 10,000 s-1 at 25 \C). The Mg2+-saturated loop II undergoes conformational exchange on the 100-$s time scale. Available data suggest that this exchange occurs between a conformation providing a ligand geometry optimized for Mg2+ binding and a conformation more similar to that of the empty loop.",
author = "A. Malmendal and J. Even{\"a}s and E. Thulin and G.P. Gippert and T. Drakenberg and S. Fors{\'e}n",
year = "1998",
doi = "10.1074/jbc.273.44.28994",
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journal = "Journal of Biological Chemistry",
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When size is important: Accommodation of magnesium in a calcium binding regulatory domain. / Malmendal, A.; Evenäs, J.; Thulin, E.; Gippert, G.P.; Drakenberg, T.; Forsén, S.

I: Journal of Biological Chemistry, Bind 273, Nr. 44, 1998.

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

TY - JOUR

T1 - When size is important: Accommodation of magnesium in a calcium binding regulatory domain

AU - Malmendal, A.

AU - Evenäs, J.

AU - Thulin, E.

AU - Gippert, G.P.

AU - Drakenberg, T.

AU - Forsén, S.

PY - 1998

Y1 - 1998

N2 - The accommodation of Mg2+ in the N-terminal domain of calmodulin was followed through amide 1H and 15N chemical shifts and line widths in heteronuclear single-quantum coherence spectroscopy NMR spectra. Mg2+ binds sequentially to the two Ca2+-binding loops in this domain, with affinities such that nearly half of the loops would be occupied by Mg2+ in resting eukaryotic cells. Mg2+ binding seems to occur without ligation to the residue in the 12th loop position, previously proven largely responsible for the major rearrangements induced by binding of the larger Ca2+. Consequently, smaller Mg2+-induced structural changes are indicated throughout the protein. The two Ca2+-binding loops have different Mg2+ binding characteristics. Ligands in the N-terminal loop I are better positioned for cation binding, resulting in higher affinity and slower binding kinetics compared with the C-terminal loop II (k(off) = 380 \ 40 s-1 compared with 10,000 s-1 at 25 \C). The Mg2+-saturated loop II undergoes conformational exchange on the 100-$s time scale. Available data suggest that this exchange occurs between a conformation providing a ligand geometry optimized for Mg2+ binding and a conformation more similar to that of the empty loop.

AB - The accommodation of Mg2+ in the N-terminal domain of calmodulin was followed through amide 1H and 15N chemical shifts and line widths in heteronuclear single-quantum coherence spectroscopy NMR spectra. Mg2+ binds sequentially to the two Ca2+-binding loops in this domain, with affinities such that nearly half of the loops would be occupied by Mg2+ in resting eukaryotic cells. Mg2+ binding seems to occur without ligation to the residue in the 12th loop position, previously proven largely responsible for the major rearrangements induced by binding of the larger Ca2+. Consequently, smaller Mg2+-induced structural changes are indicated throughout the protein. The two Ca2+-binding loops have different Mg2+ binding characteristics. Ligands in the N-terminal loop I are better positioned for cation binding, resulting in higher affinity and slower binding kinetics compared with the C-terminal loop II (k(off) = 380 \ 40 s-1 compared with 10,000 s-1 at 25 \C). The Mg2+-saturated loop II undergoes conformational exchange on the 100-$s time scale. Available data suggest that this exchange occurs between a conformation providing a ligand geometry optimized for Mg2+ binding and a conformation more similar to that of the empty loop.

U2 - 10.1074/jbc.273.44.28994

DO - 10.1074/jbc.273.44.28994

M3 - Journal article

VL - 273

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 44

ER -