Structure and expression of the cDNA encoding human neutrophil collagenase

We have isolated and characterized a 2.4-kb cDNA clone encoding human neutrophil collagenase (HNC), a member of the family of matrix metalloproteinases restricted to secondary granules within neutrophils. Partial amino acid sequence was used to deduce oligonucleotide probes. These probes were used to screen a human granulocyte cDNA library derived from messenger RNA (mRNA) from a patient with chronic granulocytic leukemia. Cell-free translation of RNA produced from the cDNA produced a 52-Kd protein that was recognized by anti-HNC antibody. The cDNA clone was sequenced and shown to encode a 467-residue protein whose sequence matched those regions currently known for HNC. The enzyme exhibits 58% homology to human fibroblast collagenase and has the same domain structure. It consists of a 20-residue signal peptide, and an 80-residue propeptide that is lost on autolytic activation by cleavage of an M-L bond. Other regions identified include the autolytic degradation site, the “cysteine switch” residue that is involved in latency and activation, and a putative zinc binding sequence. HNC has six potential N-linked glycosylation sites. The cDNA hybridized to a 3.4-kb mRNA in RNA from a patient with chronic granulocytic leukemia, but not to RNA from uninduced HL60 cells or HL60 cells that had been induced to undergo granulocytic or monocytic maturation with dimethyl sulfoxide or 12-O-tetradecanoylphorbol 13-acetate, respectively. These results parallel those seen with lactoferrin and transcobalamin I, two other secondary granule proteins.