Interstitial collagenase, also known as fibroblast collagenase and matrix metalloproteinase-1 (MMP-1), is an

enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

that in humans is encoded by the ''MMP1''

gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

. The gene is part of a cluster of MMP genes which localize to chromosome 11q22.3. MMP-1 was the first vertebrate

collagenase Collagenases are enzymes that break the peptide bonds in collagen. They assist in destroying extracellular structures in the pathogenesis of bacteria such as ''Clostridium''. They are considered a virulence factor, facilitating the spread of ...

both purified to homogeneity as a protein, and cloned as a

cDNA In genetics, complementary DNA (cDNA) is DNA that was reverse transcribed (via reverse transcriptase) from an RNA (e.g., messenger RNA or microRNA). cDNA exists in both single-stranded and double-stranded forms and in both natural and engin ...

. MMP-1 has an estimated

molecular mass The molecular mass () is the mass of a given molecule, often expressed in units of daltons (Da). Different molecules of the same compound may have different molecular masses because they contain different isotopes of an element. The derived quan ...

of 54 kDa.

Structure

MMP-1 has an archetypal structure consisting of a pre-domain, a pro-domain, a

catalytic domain In biology and biochemistry, the active site is the region of an enzyme where substrate molecules bind and undergo a chemical reaction. The active site consists of amino acid residues that form temporary bonds with the substrate, the ''binding si ...

, a linker region and a

hemopexin Hemopexin (or haemopexin; Hpx; Hx), also known as beta-1B-glycoprotein, is a glycoprotein that in humans is encoded by the ''HPX'' gene and belongs to the hemopexin family of proteins. Hemopexin is the plasma protein with the highest binding aff ...

-like domain. The primary structure of MMP-1 was first published by Goldberg, G I, ''et al.'' Two main nomenclatures for the primary structure are currently in use, the original one from which the first amino-acid starts with the signalling peptide and a second one where the first amino-acid starts counting from the prodomain (proenzyme nomenclature).

Catalytic domain

The catalytic domains of MMPs share very similar characteristics, having a general shape of oblate ellipsoid with a diameter of ~40 Å. Despite the similarity of the catalytic domains of MMPs, this entry will focus only on the structural features of MMP-1 catalytic domain.

Overall structural characteristics

The

of MMP-1 is composed of five highly twisted β-strands (sI-sV), three α-helix (hA-hC) and a total of eight loops, enclosing a total of five metal ions, three Ca²⁺ and two Zn²⁺, one of which with catalytic role. The catalytic domain (CAT) of MMP-1 starts with the F100 (non-truncated CAT) as the first amino-acid of the N-terminal loop of the CAT domain. The first published x-ray structure of the CAT domain was representative of the truncated form of this domain, where the first 7 amino-acids are not present. After the initial loop, the sequences follows to the first and longest β-sheet (sI). A second loop precedes large "amphipathic α-helix" (hA) that longitudinally spans protein site. The β-strands sII and sIII follows separated by the respective loops, loop 4 being commonly designated as "short loop" bridging sII to sIII. Following the sIII strand the sequence meets the 'S-shaped double loop' that is of primary importance for the peptide structure and catalytic activity (see further) as it extends to the cleft side "bulge", continuing to the only antiparallel β-strand sIV, which is prime importance for binding peptidic substrates or inhibitors by forming main chain

hydrogen bond In chemistry, a hydrogen bond (H-bond) is a specific type of molecular interaction that exhibits partial covalent character and cannot be described as a purely electrostatic force. It occurs when a hydrogen (H) atom, Covalent bond, covalently b ...

. Following sIV, loop Gln186-Gly192 and β-strand sV are responsible for contributing with many ligands to the several metal ions present in the protein (read further). A large open loop follows sV which has proven importance in substrate specificity within the MMPs family. A specific region (183)RWTNNFREY(191) has been identified as a critical segment of matrix metalloproteinase 1 for the expression of collagenolytic activity. On C-terminal part of the CAT Domain the hB α-helix, known as the "active-site helix" encompasses part of the "zinc-binding consensus sequence" HEXXHXXGXXH that is characteristic of the Metzincin superfamily. The α-helix hB finishes abruptly at Gly225 where the last loop of the domain starts. This last loop contains the "specificity loop" which is the shortest in the MMPs family. The Catalytic Domain ends at Gly261 with α-helix hC.

Function

MMPs are involved in the breakdown of

extracellular matrix In biology, the extracellular matrix (ECM), also called intercellular matrix (ICM), is a network consisting of extracellular macromolecules and minerals, such as collagen, enzymes, glycoproteins and hydroxyapatite that provide structural and bio ...

in normal physiological processes, such as embryonic development, reproduction, and tissue remodeling, as well as in disease processes, such as arthritis and metastasis. Specifically, MMP-1 breaks down the interstitial

collagen Collagen () is the main structural protein in the extracellular matrix of the connective tissues of many animals. It is the most abundant protein in mammals, making up 25% to 35% of protein content. Amino acids are bound together to form a trip ...

s, types I, II, and III.

Regulation

Mechanical force may increase the expression of MMP1 in human periodontal ligament cells. During cancer progression, MMP1 can be dysregulated by different mechanisms, including the activation of an insulator element located between MMP8 and MMP10 genes.

Interactions

MMP1 has been shown to

interact Advocates for Informed Choice, dba interACT or interACT Advocates for Intersex Youth, is a 501(c)(3) nonprofit organization advocating for the legal and human rights of children with intersex traits. The organization was founded in 2006 and fo ...

with

CD49b Integrin alpha-2, or CD49b (cluster of differentiation 49b), is a protein which in humans is encoded by the ''CD49b'' gene. The CD49b protein is an integrin alpha subunit. It makes up half of the α2β1 integrin duplex. Integrins are heterodimer ...

References

External links

* The

MEROPS MEROPS is an online database for peptidases (also known as proteases, proteinases and proteolytic enzymes) and their inhibitors. The classification scheme for peptidases was published by Rawlings & Barrett in 1993, and that for protein inhibito ...

online database for peptidases and their inhibitors
M10.001
* {{Portal bar, Biology, border=no Matrix metalloproteinases EC 3.4.24