Specific cleavage of recombinant protein tau3 between valine-220 and tyrosine-221 (val-309 and tyr-310 of tau4) by a double-stranded DNA-stimulated protease.
The protein tau was degraded to distinct products by a DNA-stimulated protease isolated from human leukemia HL-60 cell extracts. The enzyme partially purified by sequential chromatography on GTP-agarose, DEAE-cellulose, and TSK 3000 (0.6 X 60 mm) columns eluted as a 300-450 kDa protein which appeared as 60-90 kDa polypeptides on SDS-PAGE. Protease activity was stimulated by synthetic and natural DNAs and was most active at pH 8.5. Human recombinant tau3 was degraded by the DEAE-cellulose-eluted protease to a 26-kDa and several 14- to 16-kDa peptides. Degradation of tau was partially blocked by preincubation with tubulin, suggesting that the DNA-stimulated cleavage of tau occurred at the carboxyl-terminus, at or near the "tubulin-interactive" domains. The 26-kDa fragment was shown by amino acid sequencing to correspond to the N-terminus of tau whereas sequencing of the 16-kDa fragment yielded YKPVDLSKVT. These results show the existence of a DNA-stimulated protease capable of cleaving tau3 between valine-220 and tyrosine-221 (equivalent to valine 309 and tyrosine-310 of tau4).
Wu
J M
JM
Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, 10595, USA.
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D000595:Amino Acid Sequence; D004247:DNA / Q000378:metabolism*; D010450:Endopeptidases / Q000378:metabolism*; D004789:Enzyme Activation; D018922:HL-60 Cells; D006801:Humans; D006868:Hydrolysis; D008969:Molecular Sequence Data; D014443:Tyrosine / Q000378:metabolism*; D014633:Valine / Q000378:metabolism*; D016875:tau Proteins / Q000378:metabolism*
D016875:tau Proteins; D014443:Tyrosine; D004247:DNA; D010450:Endopeptidases; D014633:Valine