The primary structure of pepstatin-insensitive carboxyl proteinase produced by Pseudomonas sp. No. 101

Serine-Carboxyl Peptidases, Sedolisins: From Discovery to Evolution

Sedolisin is a proteolytic enzyme, listed in the peptidase database MEROPS as a founding member of clan SB, family S53. This enzyme, although active at low pH, was originally shown not to be inhibited by an aspartic peptidase specific inhibitor, S-PI (pepstatin Ac). In this Perspective, the S53 family is described from the moment of original identification to evolution. The representative enzymes of the family are sedolisin, kumamolisin, and TPP-1. They exhibit the following unique features. (1) The fold of the molecule is similar to that of subtilisin, but the catalytic residues consist of a triad, Ser/Glu/Asp, that is unlike the Ser/His/Asp triad of subtilisin. (2) The molecule is expressed as a pro-form composed of the amino-terminal prosegment and the active domain. Additionally, some members of this family have an additional, carboxy-terminal prosegment. (3) Their optimum pH for activity is in the acidic region, not in the neutral to alkaline region where subtilisin is active. (4) Their distribution in nature is very broad across the three kingdoms of life. (5) Some of these enzymes from fungi and bacteria are pathogens to plants. (6) Some of them have significant potential applications for industry. (7) The lack of a TPP-1 gene in human brain is the cause of incurable juvenile neuronal ceroid lipofuscinosis (Batten's disease).

Synergetic effects of pressure and chemical denaturant on protein unfolding: stability of a serine-type carboxyl protease, kumamolisin

Kumamolisin, a serine carboxyl proteinase, is very stable and hardly denatured by single perturbation of a chemical denaturant (urea), pressure (<500 MPa) or temperature (<65 degrees C). In order to investigate the cooperative effects of these three denaturing agents, DSC, CD, intrinsic fluorescence, and fourth derivative UV absorbance were measured under various conditions. By application of pressure to kumamolisin in 8 M urea solution, substantial red-shift in the center of fluorescence emission spectral mass was observed, and the corresponding blue-shift was observed for two major peaks in fourth derivative UV absorbance, under the similar urea-containing conditions. The denaturation curves were analyzed on the basis of a simple two-state model in order to obtain thermodynamic parameters (DeltaV, DeltaG, and m values), and the combined effects of denaturing agents are discussed, with the special interest in the large cavity and neighboring Trp residue in kumamolisin.

Effects of pressure on the activity and spectroscopic properties of carboxyl proteinases. Apparent correlation of pepstatin-insensitivity and pressure response

The pressure dependence of the activity and spectroscopic properties of four carboxyl proteinases were investigated. Two were pepstatin-sensitive carboxyl proteinases (porcine pepsin and proteinase A from baker's yeast) and two were pepstatin-insensitive carboxyl proteinases (from Pseudomonas sp. 101 (pseudomonapepsin; PCP) and Xanthomonas sp. T-22 (xanthomonapepsin; XCP)). The specificity constant [k(cat)/K(m(app))] of PCP and XCP for a synthetic peptide substrate showed only a slight decrease with increasing pressure, whereas pepsin and proteinase A showed substantial disactivation at higher pressures. The calculated apparent activation volume (Delta V((k(cat)/(K(m)) was about 1, 3, 13, and 14 mL.mol(-1) for PCP, XCP, pepsin, and proteinase A, respectively. The hydrolysis of acid-denatured myoglobin by the four carboxyl proteinases was only slightly affected by high pressure (except for proteinase A at 400 MPa), in contrast to the results for the peptide hydrolysis. In fact, PCP, XCP, and proteinase A actually showed slightly higher degradations of acid-denatured myoglobin at higher pressures. The residual activities of these enzymes after the incubation at high pressures implied a pressure-induced stabilization towards autolysis. The changes in the fourth derivative near-UV absorbance spectrum of the four enzymes in aqueous solution were measured at various pressures from 0.1 to 400 MPa. Upon an increase in pressure, the peaks from PCP and XCP red-shifted slightly, whereas pepsin and proteinase A blue-shifted substantially, thus indicating a more polar environment. The intrinsic fluorescence also decreased upon increasing pressure. However, the change for XCP was rather small, but the change for the other three was very large. The changes in the peak wavelength for pepsin and proteinase A were characteristic, and also indicated a more polar environment under high pressure. An analysis by the center of spectra mass (CSM) gave the Delta G and Delta V of transition as 9.8 kJ x mol(-1) and -24 mL x mol(-1) (pepsin) and 11.7 kJ x mol(-1) and -43 mL x mol(-1) (proteinase A), respectively, by assuming a simple two-state transition. The circular dichroism (CD) showed relatively small changes after 1-h incubations at 400 MPa, indicating that the secondary structures were largely maintained.

Biochemical characterization of a lysosomal protease deficient in classical late infantile neuronal ceroid lipofuscinosis (LINCL) and development of an enzyme-based assay for diagnosis and exclusion of LINCL in human specimens and animal models

Classical late-infantile neuronal ceroid lipofuscinosis (LINCL), a progressive and fatal neurodegenerative disease of childhood, results from mutations in a gene (CLN2) that encodes a protein with significant sequence similarity to prokaryotic pepstatin-insensitive acid proteases. We have developed a sensitive protease activity assay that allows biochemical characterization of the CLN2 gene product in various human biological samples, including solid tissues (brain and chorionic villi), blood (buffy coat leukocytes, platelets, granulocytes, and mononuclear cells), and cultured cells (lymphoblasts, fibroblasts, and amniocytes). The enzyme has a pH optimum of 3.5 and is rapidly inactivated at neutral pH. A survey of fibroblasts and lymphoblasts demonstrated that lack of activity was associated with LINCL arising from mutations in the CLN2 gene but not other neuronal ceroid lipofuscinoses (NCLs), including the CLN6 variant LINCL, classical infantile NCL, classical juvenile NCL, and adult NCL (Kufs' disease). A study conducted using blood samples collected from classical LINCL families whose affliction was confirmed by genetic analysis indicates that the assay can distinguish homozygotes, heterozygotes, and normal controls and thus is useful for diagnosis and carrier testing. Analysis of archival specimens indicates that several specimens previously classified as LINCL have enzyme activity and thus disease is unlikely to arise from mutations in CLN2. Conversely, a specimen previously classified as juvenile NCL lacks pepinase activity and is associated with mutations in CLN2. In addition, several animals with NCL-like neurodegenerative symptoms [mutant strains of mice (nclf and mnd), English setter, border collie, and Tibetan terrier dogs, sheep, and cattle] were found to contain enzyme activity and are thus unlikely to represent models for classical LINCL. Subcellular fractionation experiments indicate that the CLN2 protein is located in lysosomes, which is consistent with its acidic pH optimum for activity and the presence of mannose 6-phosphate. Taken together, these findings indicate that LINCL represents a lysosomal storage disorder that is characterized by the absence of a specific protease activity.