Elastase

In molecular biology, elastase is an enzyme from the class of proteases (peptidases) that break down proteins.^[1] In particular, it is a serine protease.^[2]

Forms and classification

Eight human genes exist for elastase:

Family	Gene symbol		Protein name		EC number
Family	Approved	Previous	Approved	Previous	EC number
chymotrypsin- like	CELA1	ELA1	chymotrypsin-like elastase family, member 1	elastase 1, pancreatic	EC 3.4.21.36
	CELA2A	ELA2A	chymotrypsin-like elastase family, member 2A	elastase 2A, pancreatic	EC 3.4.21.71
	CELA2B	ELA2B	chymotrypsin-like elastase family, member 2B	elastase 2B, pancreatic	EC 3.4.21.71
	CELA3A	ELA3A	chymotrypsin-like elastase family, member 3A	elastase 3A, pancreatic	EC 3.4.21.70
	CELA3B	ELA3B	chymotrypsin-like elastase family, member 3B	elastase 3B, pancreatic	EC 3.4.21.70
chymotrypsin	CTRC	ELA4	chymotrypsin C (caldecrin)	elastase 4	EC 3.4.21.2
neutrophil	ELANE	ELA2	neutrophil elastase	elastase 2	EC 3.4.21.37
macrophage	MMP12	HME	macrophage metalloelastase	macrophage elastase	EC 3.4.24.65

Some bacteria (including Pseudomonas aeruginosa) also produce elastase. In bacteria, elastase is considered a virulence factor.

Function

Elastase breaks down elastin, an elastic fibre that, together with collagen, determines the mechanical properties of connective tissue. The neutrophil form breaks down the Outer membrane protein A (OmpA) of E. coli and other Gram-negative bacteria. Elastase also has the important immunological role of breaking down Shigella virulence factors. This is accomplished through the cleavage of peptide bonds in the target proteins. The specific peptide bonds cleaved are those on the carboxyl side of small, hydrophobic amino acids such as glycine, alanine, and valine. For more on how this is accomplished, see serine protease.

The role of human elastase in disease

A1AT

Elastase is inhibited by the acute-phase protein α₁-antitrypsin (A1AT), which binds almost irreversibly to the active site of elastase and trypsin. A1AT is normally secreted by the liver cells into the serum. Alpha-1 antitrypsin deficiency (A1AD) leads to uninhibited destruction of elastic fibre by elastase; the main result is emphysema.

Cyclic neutropenia

The rare disease cyclic neutropenia (also called "cyclic hematopoeiesis") is an autosomal dominant genetic disorder characterised by fluctuating neutrophil granulocyte counts over 21-day periods. During neutropenia, patients are at risk for infections. In 1999, this disease was linked to disorders in the ELA-2 / ELANE gene.^[3] Other forms of congenital neutropenia also appear to be linked to ELA-2 mutations.^{[citation needed]}

Other diseases

Neutrophil elastase is responsible for the blistering in bullous pemphigoid, a skin condition, in the presence of antibodies. It may also play a role in the formation of abdominal aortic aneurysms (AAAs) and chronic obstructive pulmonary disease (COPD).

The role of bacterial elastase in disease

Elastase has been shown to disrupt tight junctions, cause proteolytic damage to tissue, break down cytokines and alpha proteinase inhibitor, cleave immunoglobulin A and G (IgA, IgG), and cleave both C3bi, a component of the complement system, and CR1, a receptor on neutrophils for another complement molecule involved in phagocytosis. The cleavage of IgA, IgG, C3bi, and CR1 contributes to a decrease of the ability of neutrophils to kill bacteria by phagocytosis. Together, all these factors contribute to human pathology.

References

^ Bieth JG (2001). "[The elastases]". J. Soc. Biol. (in French). 195 (2): 173–9. doi:10.1051/jbio/2001195020173. PMID 11723830.
^ Bruce, Alberts (2014-11-18). Molecular biology of the cell (Sixth ed.). New York, NY. ISBN 9780815344322. OCLC 887605755.{{cite book}}: CS1 maint: location missing publisher (link)
^ Horwitz M, Benson KF, Person RE, Aprikyan AG, Dale DC (1999). "Mutations in ELA2, encoding neutrophil elastase, define a 21-day biological clock in cyclic haematopoiesis". Nat. Genet. 23 (4): 433–6. doi:10.1038/70544. PMID 10581030. S2CID 6951666.

External links

GeneReviews/NCBI/NIH/UW entry on ELANE-Related Neutropenias including cyclic neutropenia

[pmid11723830-1] Bieth JG (2001). "[The elastases]". J. Soc. Biol. (in French). 195 (2): 173–9. doi:10.1051/jbio/2001195020173. PMID 11723830.

[2] Bruce, Alberts (2014-11-18). Molecular biology of the cell (Sixth ed.). New York, NY. ISBN 9780815344322. OCLC 887605755.{{cite book}}: CS1 maint: location missing publisher (link)

[3] Horwitz M, Benson KF, Person RE, Aprikyan AG, Dale DC (1999). "Mutations in ELA2, encoding neutrophil elastase, define a 21-day biological clock in cyclic haematopoiesis". Nat. Genet. 23 (4): 433–6. doi:10.1038/70544. PMID 10581030. S2CID 6951666.

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v t e Endopeptidases: serine proteases/serine endopeptidases (EC 3.4.21)
Digestive enzymes	Enteropeptidase Trypsin Chymotrypsin Elastase Neutrophil Pancreatic
Coagulation	factors: Thrombin Factor VIIa Factor IXa Factor Xa Factor XIa Factor XIIa Kallikrein PSA KLK1 KLK2 KLK3 KLK4 KLK5 KLK6 KLK7 KLK8 KLK9 KLK10 KLK11 KLK12 KLK13 KLK14 KLK15 fibrinolysis: Plasmin Plasminogen activator Tissue plasminogen activator Urinary plasminogen activator
Complement system	Factor B Factor D Factor I MASP MASP1 MASP2 C3-convertase
Other immune system	Chymase Granzyme Tryptase Proteinase 3/Myeloblastin
Venombin	Ancrod Batroxobin
Other	Acrosin Prolyl endopeptidase Pronase Proprotein convertases 1 2 Prostasin Reelin Subtilisin/Furin/S1P4 Sedolisin/TPP1 Streptokinase Cathepsin A G

v t e Enzymes
Activity	Active site Binding site Catalytic triad Oxyanion hole Enzyme promiscuity Diffusion-limited enzyme Cofactor Enzyme catalysis
Regulation	Allosteric regulation Cooperativity Enzyme inhibitor Enzyme activator
Classification	EC number Enzyme superfamily Enzyme family List of enzymes
Kinetics	Enzyme kinetics Eadie–Hofstee diagram Hanes–Woolf plot Lineweaver–Burk plot Michaelis–Menten kinetics
Types	EC1 Oxidoreductases (list) EC2 Transferases (list) EC3 Hydrolases (list) EC4 Lyases (list) EC5 Isomerases (list) EC6 Ligases (list) EC7 Translocases (list)