Crystallographic structure of Bacillus thermoproteolyticus thermolysin.
|PDB structures||RCSB PDB PDBe PDBsum|
Thermolysin (EC 22.214.171.124, Bacillus thermoproteolyticus neutral proteinase, thermoase, thermoase Y10, TLN) is a thermostable neutral metalloproteinase enzyme produced by the Gram-positive bacteria Bacillus thermoproteolyticus. It requires one zinc ion for enzyme activity and four calcium ions for structural stability. Thermolysin specifically catalyzes the hydrolysis of peptide bonds containing hydrophobic amino acids. However thermolysin is also widely used for peptide bond formation through the reverse reaction of hydrolysis. Thermolysin is the most stable member of a family of metalloproteinases produced by various Bacillus species. These enzymes are also termed 'neutral' proteinases or thermolysin -like proteinases (TLPs).
Like all bacterial extracellular proteases thermolysin is first synthesised by the bacterium as a pre-proenzyme. Thermolysin is synthesized as a pre-proenzyme consisting of a signal peptide 28 amino acids long, a pro-peptide 204 amino acids long and the mature enzyme itself 316 amino acids in length. The signal peptide acts as a signal for translocation of pre-prothermolysin to the bacterial cytoplasmic membrane. In the periplasm pre-prothermolysin is then processed into prothermolysin by a signal peptidase. The prosequence then acts as a molecular chaperone and leads to autocleavage of the peptide bond linking pro and mature sequences. The mature protein is then secreted into the extracellular medium.
Thermolysin has a molecular weight of 34,600 Da. Its overall structure consists of two roughly spherical domains with a deep cleft running across the middle of the molecule separating the two domains. The secondary structure of each domain is quite different, the N-terminal domain consists of mostly beta pleated sheet, while the C-terminal domain is mostly alpha helical in structure. These two domains are connected by a central alpha helix, spanning amino acids 137-151.
In contrast to many proteins that undergo conformational changes upon heating and denaturation, thermolysin does not undergo any major conformational changes until at least 70 °C. The thermal stability of members of the TLP family is measured in terms of a T50 temperature. At this temperature incubation for 30 minutes reduces the enzymes activity by half. Thermolysin has a T50 value of 86.9 °C, making it the most thermo stable member of the TLP family. Studies on the contribution of calcium to thermolysin stability have shown that upon thermal inactivation a single calcium ion is released from the molecule. Preventing this calcium from originally binding to the molecule by mutation of its binding site, reduced thermolysin stability by 7 °C. However, while calcium binding makes a significant contribution to stabilising thermolysin, more crucial to stability is a small cluster of N-terminal domain amino acids located at the proteins surface. In particular a phenylalanine (F) at amino acid position 63 and a proline (P) at amino acid position 69 contribute significantly to thermolysin stability. Changing these amino acids to threonine (T) and alanine (A) respectively in a less stable thermolysin-like proteinase produced by Bacillus stearothermophillus (TLP-ste), results in individual reductions in stability of 7 °C (F63→T) and 6.3 °C (P69→A) and when combined a reduction in stability of 12.3 °C.
- In the synthesis of aspartame, less bitter-tasting byproduct is produced when the reaction is catalyzed by thermolysin.
- Determining protein stability in cell lysate using the fast parallel proteolysis (FASTpp) assay.
- PDB 3TMN; Holden HM, Matthews BW (March 1988). "The binding of L-valyl-L-tryptophan to crystalline thermolysin illustrates the mode of interaction of a product of peptide hydrolysis". J. Biol. Chem. 263 (7): 3256–60. PMID 3343246.
- Endo, S. (1962). "Studies on protease produced by thermophilic bacteria". J. Ferment. Technol. 40: 346–353.
- Tajima M, Urabe I. et al. (1976). "Role of calcium ions in the thermostability of thermolysin and Bacillus subtilis var. amylosacchariticus neutral protease". Eur. J. Biochem. 64 (1): 243–247. doi:10.1111/j.1432-1033.1976.tb10293.x. PMID 819262.
- Trusek-Holownia A. (2003). "Synthesis of ZAlaPheOMe, the precursor of bitter dipeptide in the two-phase ethyl acetate-water system catalysed by thermolysin". J. Biotechnol. 102 (2): 153–163. doi:10.1016/S0168-1656(03)00024-5. PMID 12697393.
- Yasukawa K, Kusano M, Inouye K. (2007). "A new method for the extracellular production of recombinant thermolysin by co-expressing the mature sequence and pro-sequence in Escherichia coli". Protein Eng. Des. Sel. 20 (8): 375–383. doi:10.1093/protein/gzm031. PMID 17616558.
- Inouye K, Kusano M. et al. (2007). "Engineering, expression, purification, and production of recombinant thermolysin". Biotechnol. Annu. Rev. Biotechnology Annual Review 13: 43–64. doi:10.1016/S1387-2656(07)13003-9. ISBN 978-0-444-53032-5. PMID 17875473.
- Holmes MA and Matthews BW. (1982). "Structure of thermolysin refined at 1.6 A resolution". J. Mol. Biol. 160 (4): 623–639. doi:10.1016/0022-2836(82)90319-9. PMID 7175940.
- Matthews BW, Weaver LH and Kester WR. (1974). "The conformation of thermolysin". J. Biol. Chem. 249 (24): 8030–8044. PMID 4214815.
- Eijsink VG, Veltman OR, et al. (1995). "Structural determinants of the stability of thermolysin-like proteinases". Nat. Struct. Biol. 2 (5): 374–379. doi:10.1038/nsb0595-374. PMID 7664094.
- Dahlquist FW, Long JW and Bigbee WL (1976). "Role of Calcium in the thermal stability of thermolysin". Biochemistry 15 (5): 1103–1111. doi:10.1021/bi00650a024. PMID 814920.
- Yagasaki, Makoto; Hashimoto, Shin-ichi (November 2008). "Synthesis and application of dipeptides; current status and perspectives". Applied Microbiology and Biotechnology 81 (1): 13–22. doi:10.1007/s00253-008-1590-3. PMID 18795289.
- "Determining Biophysical Protein Stability in Lysates by a Fast Proteolysis Assay, FASTpp".
- The MEROPS online database for peptidases and their inhibitors: M04.001
- Thermolysin at the US National Library of Medicine Medical Subject Headings (MeSH)