Glutamic protease
 Scytalidocarboxyl peptidase B, first structure of this family of protease determined, active site cleft towards the top | |
| Identifiers | |
|---|---|
| Symbol | ? |
| MEROPS | G1 |
Glutamic proteases are a group of proteolytic enzymes containing a glutamic acid residue within the active site. This type of protease was first described in 2004 and became the sixth catalytic type of protease.[1] Members of this group of protease had been previously assumed to be an aspartate protease, but structural determination showed it to belong to a novel protease family. The first structure of this group of protease was scytalidoglutamic peptidase, the active site of which contains a catalytic dyad, glutamic acid (E) and glutamine (Q), which give rise to the name eqolisin. This group of proteases are found primarily in pathogenic fungi affecting plant and human.[2]
Distribution and types
This group of proteases have a limited distribution, and were originally thought to be limited to filamentous fungi mainly in the Ascomycota phylum.[3] Subsequently, however, glutamic proteases have been identified in bacteria and archaea.[4]
These proteases were first identified in the fungi Scytalidium lignicola and Aspergillus niger var. macrosporus, from which scytalidoglutamic peptidase (eqolisin) and aspergilloglutamic peptidase are derived respectively. These two proteases contain active site Glu and Gln residues and are grouped under MEROPS family G1.[5][6]
A convergently evolved glutamic peptidase, the pre-neck appendage protein (bacteriophage phi-29), uses a Glu and an Asp residue at the active site, and is classified as MEROPS family G2.[7]
Properties
These enzymes are acid proteases; eqolisin for example is most active at pH 2.0 when casein is used as substrate.[2] Eqolosins prefer bulky amino acid residues at the P1 site and small amino acid residues at the P1′ site. A characteristic of the protease is its insensitivity to pepstatin and S-PI (acetyl pepstatin) and it was previously classed as "pepstatin-insensitive carboxyl proteinases".[8] The other "pepstatin-insensitive carboxyl proteinases" belongs to subfamily of serine protease, serine-carboxyl protease (sedolisin) which was discovered in 2001.[2] These proteases are also not inhibited by DAN (diazoacetyl-DL-norleucine methylester) (7) but may be inhibited by EPNP (1,2-epoxy-3-(p-nitrophenoxy) propane).[9][10]
Active site and mechanism of catalysis
The active site of eqolosin contains a distinctive glutamic acid and glutamine dyad which are involved in substrate binding and catalysis. These residues act as a nucleophile, with the glutamic acid serving as a general acid in the first phase of the reaction, donating a proton to the carbonyl oxygen in the peptide bond of the substrate. One or two water molecules may be involved in the reaction supplying a hydroxyl group, and the glutamic acid further donates a proton to the amide nitrogen, resulting in breakage of the peptide bond. The glutamine then returns the glutamic acid to its initial state.[11]
References
- ^ Masao Fujinaga, Maia M. Cherney, Hiroshi Oyama, Kohei Oda, Michael N. G. James (2004). "The molecular structure and catalytic mechanism of a novel carboxyl peptidase from Scytalidium lignicolum". Proc Natl Acad Sci U S A. 101 (10): 3364–9. doi:10.1073/pnas.0400246101. PMID 14993599.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ a b c Kohei Oda (2012). "New families of carboxyl peptidases: serine-carboxyl peptidases and glutamic peptidases". Journal of Biochemistry. 151 (1): 13-25. doi:10.1093/jb/mvr129. PMID 22016395.
- ^ Andrew H. Sims, Nigel S. Dunn-Coleman, Geoffrey D. Robson, Stephen G. Oliver (2004). "Glutamic protease distribution is limited to filamentous fungi". FEMS Microbiol Lett. 239 (1): 95–101. doi:10.1016/j.femsle.2004.08.023. PMID 15451106.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Jensen K1, Østergaard PR, Wilting R, Lassen SF (2010). "Identification and characterization of a bacterial glutamic peptidase". BMC Biochem. 11 (47). doi:10.1186/1471-2091-11-47. PMID 21122090.
{{cite journal}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link) CS1 maint: unflagged free DOI (link) - ^ Sasaki H1, Kubota K, Lee WC, Ohtsuka J, Kojima M, Iwata S, Nakagawa A, Takahashi K, Tanokura M. (2012). "The crystal structure of an intermediate dimer of aspergilloglutamic peptidase that mimics the enzyme-activation product complex produced upon autoproteolysis". Journal of Biochemistry. 152 (1): 45–52. doi:10.1093/jb/mvs050. PMID 22569035.
{{cite journal}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link) - ^ Takahashi K (2013). "Structure and function studies on enzymes with a catalytic carboxyl group(s): from ribonuclease T1 to carboxyl peptidases". Proc Jpn Acad Ser B Phys Biol Sci. 89 (6): 201–25. doi:10.2183/pjab.89.201.
- ^ "Family G2". MEROPS.
- ^ "Family G1". MEROPS.
- ^ Murao S, Oda K, Matsushita Y. (1973). "Isolation and identification of a microorganism which produces non Streptomyces pepsin inhibitor and N-diazoacetyl-DL-norleucine methylester sensitive acid proteases". Agric. Biol. Chem. 37: 1417–1421. doi:10.1271/bbb1961.37.1417.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Morihara K, Tsuzuki H, Murao S, Oda K. (1979). "Pepstatin-insenstive acid proteases from Scytalidium lignicolum. Kinetic study with synthetic peptides". Journal of Biochemistry. 85 (3): 661–8. PMID 34596.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Moselio Schaechter, ed. (2009). Encyclopedia of Microbiology (3rd ed.). Academic Press. p. 499. ISBN 978-0123739391.