Plant matrix metalloproteinases are metalloproteins and zinc enzymes found in plants.
Matrix Metalloproteinase Matrix metalloproteinases (MMPs) are zinc endopeptidases, commonly called metzincins. MMP enzymes represent an ancient family of proteins with major similarities in genetic make-up that are present in a range of diverse organisms from unicellular bacteria to multicellular vertebrates and invertebrates. The superfamily is distinguished due to its motif consisting of three histidines bonded to zinc at the catalytic site. The metzincins are divided into four smaller families: seralysins, astacins, adamalysins (ADAMs), and MMPs. The MMP family is formed by twenty related zinc-dependent enzymes. They are noted for having the ability to degrade extracellular matrix proteins, such as collagens, laminin, and proteoglycans. These calcium- and zinc-dependent proteases are activated at neutral pH and twenty-three have been found present in mammalian cells. Plant MMPs show structural similarity to MMPs found in mammals, such as the presence of an auto-regulatory cysteine switch domain and a zinc-binding catalytic domain. MMPs are synthesized primarily by connective tissues and have a large contribution to the initial events of tissue degradation. There are three major groups of the MMP family and each group has more than one distinct gene product that distinguishes them apart from one another on the immunological and biochemical criteria. Similar to that of induced fit by enzyme-substrate interactions, MMPs in the first group, called collagenases, have interstitial collagens. The second group, called gelatinases, degrade denatured collagens catalytically. The third group, called stromelysins, have the broadest proteolytic action and were originally confused as proteoglyconases. A less clearly described group of MMPs is the PUMP. Its RNA was taken from stromal cells in human breast carcinomas. Based on the PUMP sequence and functionality of carcinomas in the progression of malignancy, a new branch of the MMP family could have been discovered.
Extracellular Matrix The most basic description of the plant extracellular matrix (ECM) is the cell wall, but it is actually the cell surface continuum that includes a variety of proteins with major roles in plant growth, development, and response. The ECM is composed of the primary and secondary cell walls, along with the intercellular gap between its neighboring cells. The ECM has a functional structure, along with aid in the regulation of turgor, which acts as a protective barrier and communicates with other cells using signaling pathways. In mammalian animals, extracellular matrix metalloproteinases (MMPs) modify the ECM to play significant roles in biological processes. The important role of MMP function in the extracellular matrix modification and subsequent mammalian development and signaling suggests that further study on the structure and function of these extracellular metalloproteinases may reveal new aspects of ECM modification in plant development.
Plant MMPs All known MMPs have been studied in vertebrates; it is hypothesized that they are involved in remodeling connective tissue during development and healing. Current advances are being made in the field of Biochemistry, which will further analyze MMP-ECM interaction and their effects during plant development, stress induction, and xylem-phloem differences. SMEP1, soybean metalloendoproteinase 1, has been sequenced and characterized. It is noted that several unique divergences are in SMEP1 from that of the normal MMP family. For example, SMEP1 is said to have a free cysteine at position 94, a non-homologous insert from V103 to S121, a free sulfhydryl group, and the complete lack of the aspartate that is found in all of the other MMPs.
… excerpt ends here. Continue reading the full article.
