Journal
BIOCHEMICAL JOURNAL
Volume 420, Issue -, Pages 115-122Publisher
PORTLAND PRESS LTD
DOI: 10.1042/BJ20081405
Keywords
alpha-kinase; atypical protein kinase; domain swapping; ion channel; transient receptor potential (TRP) channel; transient receptor potential melastatin 7 (TRPM7)
Categories
Funding
- Canadian Institutes of Health Research [MOP8603]
Ask authors/readers for more resources
TRPM7 (transient receptor potential melastatin) combines an ion channel domain with a C-terminal protein kinase domain that belongs to the atypical alpha-kinase family. The TRPM7 alpha-kinase domain assembles into a dimer through the exchange of an N-terminal segment that extends from residue 1551 to residue 1577 [Yamaguchi, Matsushita, Nairn and Kuriyan (2001) Mol. Cell 7, 1047-1057]. Here, we show, by analysis of truncation mutants, that residues 1553-1562 of the N-terminus are essential for kinase activity but not dimer formation. Within this 'activation sequence', site-directed mutagenesis identified Tyr-1553 and Arg-1558 as residues critical for activity. Examination of the TPPM7 kinase domain structure suggests that the activation sequence interacts with the other subunit to help position a catalytic loop that contains the invariant Asp-1765 residue. Residues 15631570 of the N-terminal segment are critical for dimer assembly. Mutation of Leu-1564, Ile-1568 or Phe-1570 to alanine abolished both kinase activity and dimer formation. The activity of a monomeric TRPM7 kinase domain lacking the entire N-terminal segment was rescued by a GST (glutathione transferase) fusion protein containing residues 1548-1576 of TRPM7, showing that all interactions essential for activity are provided by the N-terminal segment. Activity was also restored by GST fused to the N-terminal segment of TRPM6 (residues 1711-1740), demonstrating the feasibility of forming functional TPPM6-TRPM7 alpha-kinase domain heterodimers. It is proposed that covalent modifications or binding interactions that alter the conformation of the N-terminal exchanged segment may provide a means to regulate TRPM7 kinase activity.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available