The propeptide domain of membrane type 1-matrix metalloproteinase acts as an intramolecular chaperone when expressed in trans with the mature sequence in COS-1 cells.
It has been assumed that cleavage of the N-terminal propeptide domain of membrane type-1 matrix metalloproteinase (MT1-MMP) is required for enzyme function. We recently demonstrated that the propeptide domain of MT1-MMP is not cleaved and actually is required for function of the membrane-bound enzyme in transfected COS-1 cells (Cao, J., Drews, M., Lee, H. M., Conner, C., Bahou, W. F., and Zucker, S. (1998) J. Biol. Chem. 273, 34745-34752). In this report, we have inserted the cDNA encoding the signal and propeptide sequences of MT1-MMP (MT(1-109)) and the cDNA encoding propeptide-deleted mature MT1-MMP (MT delta pro) in expression vectors that were then transfected into matrix metalloproteinase-deficient COS-1 cells. Co-expression of both the mature sequence and the prosequence of MT1-MMP as independent polypeptides (in trans) in COS-1 cells resulted in reconstitution of MT1-MMP function in terms of facilitating (125)I-labeled tissue inhibitor of metalloproteinase 2 binding to transfected cells and subsequent activation of progelatinase A. Transfection of cells with either cDNA alone resulted in non-functional cells. These results are consistent with the propeptide sequence of MT1-MMP functioning as an intramolecular chaperone involved in protein folding and trafficking to the cell surface.
Cao
J
J
Department of Medicine, State University of New York at Stony Brook, Stony Brook, New York 11794, USA.
Hymowitz
M
M
Conner
C
C
Bahou
W F
WF
Zucker
S
S
D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D018076:DNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic; D020781:Matrix Metalloproteinase 1 / Q000096:biosynthesis / Q000235:genetics*; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D011498:Protein Precursors / Q000096:biosynthesis / Q000235:genetics; D016415:Sequence Alignment
D018076:DNA, Complementary; D018832:Molecular Chaperones; D011498:Protein Precursors; D020781:Matrix Metalloproteinase 1