Identification and characterization of a novel human matrix metalloproteinase with unique structural characteristics, chromosomal location, and tissue distribution.
We have cloned a novel member of the matrix metalloproteinase (MMP) family of proteins from a human liver cDNA library. The isolated cDNA contains an open reading frame coding for a polypeptide of 508 amino acids, which has been tentatively called MMP-19. This protein exhibits the domain structure characteristic of previously described MMPs, including a signal sequence, a prodomain with the cysteine residue essential for maintaining the latency of these enzymes, an activation locus with the zinc-binding site, and a COOH-terminal fragment with sequence similarity to hemopexin. However, it lacks a series of structural features distinctive of the diverse MMP subclasses, including the Asp, Tyr, and Gly residues located close to the zinc-binding site in collagenases, the fibronectin-like domain of gelatinases, the transmembrane domain of membrane-type (MT) MMPs, and the furin-activation sequence common to stromelysin-3 and MT-MMPs. In addition, the 9-residue insertion rich in hydrophobic amino acids present at the hinge region in stromelysins is replaced in MMP-19 by a longer insertion very rich in acidic residues. On the basis of these structural characteristics, we propose that MMP-19 does not belong to any of the previously defined MMP-subclasses and may represent the first member of a new MMP subfamily. Chromosomal location of the MMP-19 gene revealed that it maps to chromosome 12q14, which is also a unique location for any MMPs mapped to date. The cDNA encoding a full-length MMP-19 was expressed in Escherichia coli, and after purification and refolding, the recombinant protein was able to degrade synthetic substrates for MMPs. MMP-19 proteolytic activity was abolished by TIMP-2 and EDTA, thus providing additional evidence that the isolated cDNA codes for an authentic MMP. Northern blot analysis of polyadenylated RNAs isolated from a variety of human tissues revealed that MMP-19 is mainly expressed in placenta, lung, pancreas, ovary, spleen, and intestine, suggesting that it may play a specialized role in these tissues.
Pendás
A M
AM
Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad de Oviedo, 33006-Oviedo, Spain.
Knäuper
V
V
Puente
X S
XS
Llano
E
E
Mattei
M G
MG
Apte
S
S
Murphy
G
G
López-Otín
C
C
D000595:Amino Acid Sequence; D001483:Base Sequence; D015152:Blotting, Northern; D002874:Chromosome Mapping; D002881:Chromosomes, Human, Pair 12; D003001:Cloning, Molecular; D018076:DNA, Complementary; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D008099:Liver / Q000201:enzymology; D053505:Matrix Metalloproteinases, Secreted; D008666:Metalloendopeptidases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid
D018076:DNA, Complementary; D053505:Matrix Metalloproteinases, Secreted; D008666:Metalloendopeptidases; C108362:matrix metalloproteinase 19