16001967

pubmed:Citation

5

Presenilins (PS) are thought to contain the active site for presenilinase endoproteolysis of PS and gamma-secretase cleavage of substrates. The structural requirements for PS incorporation into the gamma-secretase enzyme complex, complex stability and maturation, and appropriate presenilinase and gamma-secretase activity are poorly understood. We used rescue assays to identify sequences in transmembrane domain one (TM1) of PS1 required to support presenilinase and gamma-secretase activities. Swap mutations identified an N-terminal TM1 domain that is important for gamma-secretase activity only and a C-terminal TM1 domain that is essential for both presenilinase and gamma-secretase activities. Exchange of residues 95-98 of PS1 (sw95-98) completely abolishes both activities while the familial Alzheimer's disease mutation V96F significantly inhibits both activities. Reversion of residue 96 back to valine in the sw95-98 mutant rescues PS function, identifying V96 as the critical residue in this region. The TM1 mutants do not bind to an aspartyl protease transition state analog gamma-secretase inhibitor, indicating a conformational change induced by the mutations that abrogates catalytic activity. TM1 mutant PS1 molecules retain the ability to interact with gamma-secretase substrates and gamma-secretase complex members, although Nicastrin stability is decreased by the presence of these mutants. gamma-Secretase complexes that contain V96F mutant PS1 molecules display a partial loss of function for gamma-secretase that alters the ratio of amyloid-beta peptide species produced, leading to the amyloid-beta peptide aggregation that causes familial Alzheimer's disease.

eng

IM

MEDLINE

0022-3042

Print

NLM

1315-28

pubmed-meshheading:16001967-Amino Acid Sequence, pubmed-meshheading:16001967-Amyloid Precursor Protein Secretases, pubmed-meshheading:16001967-Animals, pubmed-meshheading:16001967-Aspartic Acid Endopeptidases, pubmed-meshheading:16001967-Cells, Cultured, pubmed-meshheading:16001967-Drug Stability, pubmed-meshheading:16001967-Endopeptidases, pubmed-meshheading:16001967-Endoplasmic Reticulum, pubmed-meshheading:16001967-Fibroblasts, pubmed-meshheading:16001967-Homeostasis, pubmed-meshheading:16001967-Humans, pubmed-meshheading:16001967-Membrane Glycoproteins, pubmed-meshheading:16001967-Membrane Proteins, pubmed-meshheading:16001967-Mice, pubmed-meshheading:16001967-Mice, Knockout, pubmed-meshheading:16001967-Molecular Sequence Data, pubmed-meshheading:16001967-Mutagenesis, Site-Directed, pubmed-meshheading:16001967-Presenilin-1, pubmed-meshheading:16001967-Protein Structure, Tertiary

Two domains within the first putative transmembrane domain of presenilin 1 differentially influence presenilinase and gamma-secretase activity.

Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural