Structure-function relationships in the Ca(2+)-binding and translocation domain of SERCA1: physiological correlates in Brody disease.
Alanine-scanning mutagenesis of all amino acids in transmembrane helices M4, M5, M6 and M8, which contain known Ca2+ binding residues in the Ca(2+)-ATPase of skeletal muscle sarcoplasmic reticulum, revealed patches of mutation-sensitivity in M4, M5 and M6, but in M8. A six-residue motif, (E/D)GLPA(T/V), in M4 and M6 and its counterpart in M5 were highlighted by mutagenesis. Site-directed disulfide mapping of helices M4 and M6 demonstrated that these transmembrane helices associate as a right-handed coiled-coil. This structural information, combined with the earlier analysis of the association of each Ca2+ binding residue with either Ca2+ binding site I or site II, permitted the development of a "side-by-side" model for the two Ca2+ binding sites in the Ca(2+)-ATPase. In about half of Brody disease families, mutations create stop codons which delete all or part of the Ca2+ binding and translocation domain, resulting in loss of SERCA1 function and muscle disease.
MacLennan
D H
DH
Banting and Best Department of Medical Research, University of Toronto, Ontario, Canada.
Rice
W J
WJ
Odermatt
A
A
Green
N M
NM
D000595:Amino Acid Sequence / Q000235:genetics; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D009135:Muscular Diseases / Q000235:genetics*; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*; D013329:Structure-Activity Relationship; D014178:Translocation, Genetic / Q000235:genetics*
D000252:Calcium-Transporting ATPases; D002118:Calcium