Aggresome formation and pharmacogenetics: sulfotransferase 1A3 as a model system.
A common cause for pharmacogenetic alteration in drug response is genetic variation in encoded amino acid sequence. We have used the catecholamine and drug-metabolizing enzyme sulfotransferase (SULT)1A3 to create an artificial model system to study mechanisms-especially possible aggresome formation-by which genetic alteration in amino acid sequence might influence function. Specifically, we created a double variant SULT1A3 allozyme that included the naturally occurring Asn234 polymorphism plus an additional Trp172Arg mutation. Analysis of the SULT1A3 X-ray crystal structure had indicated that the Trp172Arg mutation might destabilize the protein's structure. Expression of SULT1A3 Arg172,Asn234 in COS-1 cells resulted in undetectable enzyme activity and a virtual lack of enzyme protein. Rabbit reticulocyte lysate degradation studies showed that the double variant allozyme was degraded much more rapidly than was wild type SULT1A3 by a ubiquitin-proteasome-dependent process. In addition, after expression in COS-1 cells, the double variant allozyme localized to aggresomes, a process not previously described or studied in pharmacogenetics. Therefore, the alteration of only one or two amino acids can lead to decreased levels of protein as a result of both aggresome formation and accelerated degradation. The possible role of aggresome formation in pharmacogenetics should be evaluated in naturally occurring systems with inherited alteration in encoded amino acid sequence.
Wang
Liewei
L
Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Medical School-Mayo Clinic-Mayo Foundation, Rochester, MN 55905, USA.
Yee
Vivien C
VC
Weinshilboum
Richard M
RM
D019943:Amino Acid Substitution; D000818:Animals; D015239:Arylsulfotransferase; D001216:Asparagine / Q000235:genetics; D019556:COS Cells; D002522:Chlorocebus aethiops; D018360:Crystallography, X-Ray; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D006801:Humans; D002479:Inclusion Bodies / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D007527:Isoenzymes; D007976:Leupeptins / Q000494:pharmacology; D008958:Models, Molecular; D010597:Pharmacogenetics; D011110:Polymorphism, Genetic; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D061988:Proteasome Inhibitors; D011487:Protein Conformation; D011817:Rabbits; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012156:Reticulocytes / Q000737:chemistry / Q000378:metabolism; D015238:Sulfotransferases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D014364:Tryptophan / Q000235:genetics; D014452:Ubiquitins / Q000037:antagonists & inhibitors / Q000378:metabolism
D015853:Cysteine Proteinase Inhibitors; D007527:Isoenzymes; D007976:Leupeptins; D061988:Proteasome Inhibitors; D011994:Recombinant Proteins; D014452:Ubiquitins; D001216:Asparagine; D014364:Tryptophan; D015238:Sulfotransferases; D015239:Arylsulfotransferase; C403170:monoamine-sulfating phenol sulfotransferase; D046988:Proteasome Endopeptidase Complex; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde