Conclusion - Nf-ESPs induced MAPKs activation in BV2 cells

E. Nf-ESPs induced MAPKs activation in BV2 cells

V. Conclusion

To understand contact-independent pathogenesis of N. fowleri in PAM, the change and immune responses in BV2 cells induced by Nf-ESPs were analyzed.

The treatment of Nf-ESPs to BV2 cells markedly reduced cell viability of the cells, which suggesting possible roles of Nf-ESPs in cell damages observed in PAM.

Treatment of Nf-ESPs induced increased expressions of, especially IL-1α and TNF- α, various cytokine and chemokines in BV2 cells. To further understand the mechanism of expression of pro-inflammatory cytokines, MAPK such as P38, JNK and ERK activation were slightly increased by treatment of Nf-ESPs. These results suggested that Nf-ESPs induced productions of pro-inflammatory cytokines, which will further activate inflammation responses in the microglia during the PAM. Therefore, Nf-EPSs can be an important factor in contact-independent pathogenic mechanism of N. fowleri. Considering to Nf-ESPs is a mixture of various proteins secreted by the amoeba, further detailed studies to determine which protein is closely related to the pathogenic mechanism of Nf-ESPs should be needed.

References

1. Aichelburg AC, Walochnik J, Assadian O, Prosch H, Steuer A, Perneczky G, Visvesvara GS, Aspock H, Vetter N: Successful treatment of disseminated Acanthamoeba sp. infection with miltefosine. Emerg Infect Dis 14(11): 1743-1746, 2008

2. Aloisi F: Immune function of microglia. Glia 36(2): 165-179, 2001.

3. Bankers-Fulbright JL, Kalli KR, McKean DJ: Interleukin-1 signal transduction.

Life Sci 59(2): 61-83, 1996

4. Bauman RW; "Microbial Diseases of the Nervous System and Eyes".

Microbiology, With Diseases by Body System (2nd ed.). San Francisco:

Pearson Education. p. 617, 2009

5. Brown T: Observations by immunofluorscence microscopy and electron microscopy on the cytopathogenicity of Naegleria fowleri in mouse embryo culutres. J Med Microbiol 12:355-362, 1979

6. Brynskov J, Foegh P, Pedersen G, Ellervik C. Kirkegaard T, Bingham A, Saemark T: Tumour necrosis factor alpha converting enzyme (TACE) activity in the colonic mucosa of patients with inflammatory bowel disease. Gut 51(1):

37-43, 2002

7. Buckner LR, Lewis ME, Greene SJ, Foster TP, Quayle AJ: Chlamydia trachomatis infection results in a modest pro-inflammatory cytokine response

and a decrease in T cell chemokine secretion in human polarized endocervical epithelial cells. Cytokine 63(2): 151-165, 2013

8. Carter RF: Description of a Naegleria species isolated from two cases of primary amoebic meningoencephalitis and of the experimental pathological changes induced by it. J Pathol 100: 217-244, 1970

9. Carter RF: Primary amoebic meningo-encephalitis. An appraisal of present knowledge. Trans R Soc Trop Med Hyg 66: 193-213, 1972

10. Carter RF: Primary amoebic meningoencephalitis: clinical, pathological and epidemiological features of six fatal cases. J Pathol Bacteriol 96: 1-25, 1968 11. Centers for Disease Control Prevention (CDC): Primary amebic

meningoencephalitis—Arizona, Florida, and Texas, 2008. MMWR Morb Mortal Wkly Rep 57: 573-577, 2007

12. Cervantes-Sandoval L, Serrano-Luna Jde J, Garcia-Latorre E, Tsutsumi V, Shibayama M: Mucins in the host defence against Naegleria fowleri and mucinolytic activity as a possible means of evasion. Microbiology 154(Pt 12):

3895-3904, 2008

13. Chao CC, Anderson WR, Hu S, Gekker G, Martella A, Peterson PK: Acvated microglia inhibit multiplication of Toxoplasma gondii via a nitric oxide mechanism. Clin Immunol Immunopathol 67: 178-183, 1993

14. Chao CC, Gerkker G, Hu S, Peterson PK: Human microglial cell defense against Toxoplasma gondii. The role of cytokines. J Immunol 152: 1246-1252,

1994

15. Chao CC, Hu S, Close K, Choi CS, Molter TW, Novick WJ, Peterson PK:

Cytokine release from microglia: differential inhibition by pentoxifylline and dexamethasone. J Infect Dis 166: 847-853, 1992

16. Chao CC, Hu S, Peterson PK: Glias: the not so innocent bystanders. J Neurovirol 2: 234-239, 1996

17. Crawford GD,Whler DJ, Dinarello CA: Parasite-monocyte interactions in human leishmaniasis: production of interleukin-1 in vitro. J Infect Dis 152(2):

315-322, 1985

18. Culberson GC: The pathogenicity of soil amoebas. Annu Rev Microbiol 25:

231-254, 1971

19. da Rocha-Azevedo B, Tanowitz HB, Marciano-Cabral F. Diagnosis of infections caused by pathogenic free-living amoebae. Interdiscip Perspect Infect Dis 251406, 2009

20. De Jonckheere JF: Characterization of Naegleria species by restriction endonuclease digestion fo whole-cell DNA. Mol Biochem Parasitol 24: 55-66, 1987

21. De Jonckheere JF: Isoenzyme patterns of pathogenic and non-pathogenic Naegleria spp. Using agarose isoelectirc focusing. Ann Microbiol 133(2):

3193-3142, 1982

22. Deetz TR, Sawyer MH, Billman G, Schuster FL, Visvesvara GS: Successful

treatment of Balamuthia amoebic encephalitis: presentation of 2 cases. Clinical Infect Dis 37 (10): 1304-1312, 2003

23. Derr-Harf and De Jonckheere JF: Isolation of pathogenic Naegleria australiensis (Amoebida, Vahlkampfidae) from the Rhine. Protistologica 302:

489-494, 1984

24. Dinarello CA: Interleukin-1 and its biologically related cytokines. Adv Immunol 44: 153-205, 1989

25. Dinarello CA: Interleukin-1 in the pathogenesis and treatment of inflammatory diseases. Blood 117(14): 3720-3732, 2011

26. Dinarello CA: Interneukin-1. Cytokine Growth Facor Rev 8(4): 253-265, 1997 27. Dinarello CA: Role of pro- and anti-inflammatory cytokines during

inflammation: experimental and clinical findings. J Biol Regul Homeost Agents 11(3): 91-103, 1997

28. Dingle AD and Fulton C: Development of the flagellar apparatus of Naegleria.

J Cell Biol 31: 43-54, 1966

29. Dowlati Y, Herrmann N, Swardfager W, Liu H, Sham L, Reim EK, Lanctot KL:

A meta-analysis of cytokines in major depression. Biol Psychiatry 67(5): 446-457, 2010

30. Ferrant A and Bates EJ: Elastase in the pathogenic free-living amebae Naegleria and Acanthamoeba spp. Infec Immun 56: 3320-3321, 1988

31. Fischer HG, Nitzgen B, Reichmann G, Hadding U: Cytokine responses

induced by Toxoplsma gondii in astrocytes and microglial cells. Eur J Immunol 27(6): 1539-1548, 1997

32. Fulton C: Cell differentiation in Naegleria gruberi. Annu Rev Microbiol 31:

597-629, 1977

33. Gehrmann J, Matsumoto Y, Kreutzberg GW: Microglia: intrinsic immuneffector cell of the brain. Brain Res Brain Res Rev 20(3): 269-287, 1995 34. Hadas E and Mazur T: Characterization of ameboid microglia isolated from

developing mammalian brain. Trop Med Parasitol 44: 197-200, 1993

35. Hu S, Sheng WS, Peterson PK, Chao CC: Cytokine modulation of rat microglial cell superoxide production. Glia 13: 45-50, 1995

36. John DT, Cole TB Jr, Bruner RA: Amebostomes of Naegleria fowleri. J protozool 32: 12-19, 1985

37. John DT, Cole TB Jr, Marciano-Cabral FM: Sucker-like structures on the pathogenic amoeba Naegleria fowleri. Appl Environ Microbiol 47: 12-14, 1984 38. John DT: Primary amebic meningoencephalitis and the biology of Naegleria

fowleri. Annu Rev Microbiol 36: 101-123, 1982

39. Jung SY, Kim JH, Lee YJ, Song KJ, Kim K, Park S, Im KI, Shin HJ: Naegleria fowleri: nfa1 gene knock-down by double-stranded RNAs. Exp Parasitol 118:

208-213, 2008

40. Kaminsky R: Miltefosine Zentaris. Curr Opin Investig Drug 3: 550-554, 2002 41. Katafuchi T, Takaki A, Take S, Kondo T, Yhshimura M: Endotoxin inhibitor

blocks heat exposure-induced expression of brain cytokine mRNA in aged rat.

Brain Res Mol Brain Res 118(1-2): 24-32, 2003

42. Khan NA, Jarrol EL, Panjwani N, Cao Z, Paget TA: Protease as markers for differentiation of pathogenic and non-pathogenic species of Acanthamoeba. J Clin Microbiol 43: 391-318, 2000

43. Kim JH, Jung SY, Lee YJ, Song KJ, Kwon D, Kim K, Park S, Im KI, Shin HJ:

Effect of therapeutic chemical agents in vitro and on experimental meningoencephalitis due to Naegleria fowleri. Antimicrob Agents Chemother 52: 4010-4016, 2008

44. Kim JH, Song AR, Sohn HJ, Lee J, Yoo JK, Kwon D, Shin HJ: IL-1beta and IL-6 activate inflammatory response of astrocytes against Naegleria fowleri infection via the modulation of MAPKs and AP-1. Parasite Immunol 35(3-4):

120-128, 2013

45. Kim JH, Yang AH, Sohn HJ, Kim D, Song KJ, Shin HJ: Immunodominant antigens in Naegleria fowleri excretory--secretory proteins were potential pathogenic factors. Parasitol Res 105(6):1675-1681, 2009

46. Lattyak M, Cabral G, Marciano-Cabral F: Scanning electron microscopy of trophozoites of Naegleria species. Proc Elect Microsc Soc Am 43: 642-643, 1985

47. Lether H, Silvany R, Alizadeh H, Huang J, Niederkorn JY: Mannose induce the release of cytophathic factors from Acanthamoeba Keratitis. Infect Immun 66:

5-10, 1998

48. Locksley RM, Killeen N, Leonardo MJ: The TNF and TNF receptor superfamilies: integrating mammalian biology. Cell 104(4): 487-501, 2001 49. Ma P, Visvesvara GS, Martinez AJ, Theodore FH, Daggett PM, Sawyer TK:

Naegleria and Acanthamoeba infections: review. Reviews infect dis 12(3): 490-513, 1990

50. Maher FO, Martin DS, Lynch MA: Increased IL-1beta in cortex of aged rats is accompanied by downregulation of ERK and PI-3 kinase. Neurobiol Aging 25(6): 795-806, 2004

51. Manning G, Whyte DB, Martinez R, Hunter T, Sudarsanam S: The portein kinase complement of the human genome. Science 298(5600): 1912-1934, 2002

52. Marciano-Cabral F and Fulford DE: Cytopathology of pathogenic and nonpathogenic Naegleria species for cultured rat neuroblastoma cells. Appl Eviron Microbiol 51: 1133-1137, 1986

53. Marciano-Cabral F and John DT: Cytophathologenicity of Naegleria fowleri for rat neuroblastoma cell cultures: scanning electron microscopy study. Infect Immun 40: 1214-1217, 1983

54. Marciano-Cabral F, MacLean R, Mensah A, LaPat-Polasko L: Identification of Naegleria fowleri in domestic water sources by nested PCR. Appl Envion Microbiol 69: 5864-5869, 2003

55. Marciano-Cabral F, Patterson M, John DT, Bradley SG: Cytopathogenicity of Naegleria fowleri and Naegleria gruberi for established mammalian cell cultures. J Parasitol 68: 1110-1116, 1982

56. Marciano-Cabral F, Puffenbarger R, Cabral GA: The increasing importance of Acanthamoeba infections. J Eukaryot Microbiol 47(1): 29-36, 2000

57. Marciano-Cabral F: Biology of Naegleria spp. Microbiol Rev 52: 114-133, 1988

58. Martinez AJ: Free living amebas: natural history, prevention, diagnosis, pathology and treatment of the disease. Boca Raton: CRC Press Inc 156, 1985 59. Martinez DY, Seas C, Bravo F, Legua P, Ramos C. Cabello AM, Gotuzzo E:

Successful treatment of Balamuthia mandrillaria amoebic infection with extensive neurological and cutaneous involvement. Clin Infect Dis 51(2): e7-e11, 2010

60. Mikocka-Walus A, Turnbull DA, Moulding NT, Wilson IG, Andrews JM, Holtmann GJ: Controversies surrounding the comorbidity of depression and anxiety in inflammatory bowel disease patients: a literature review. Inflamm Bowel Dis 13(2): 225-234, 2007

61. Mitra MM, Alzadeh H, Gerard HR, Niederkorn JY: Characterization of plasminogen activator produced by Acanthamoeba castellanii. Mol Biochem Parasitol 73:157-164, 1995

62. Mitro K, Bhagavathiammai A, Zou OM, Bobbett G, McKERROW JH,

Chokshi R, Chokshi B, James ER: Partial characterization of the proteolytic secretions of Acanthamoeba polyphaga. Exp Parasitol 78: 377-385

63. Murray-Calderon P and Connolly MA: Interleukin-1 beta inhibits glutamate release in hippocamous of young, but not aged, rats. Neurobiol Aging 18(3):

343-348, 1997

64. Nakajuma K and Kohsaka S: Function roles of microglia in the brain: (Review).

Neurosci Res 17: 187, 1993

65. Nmorsi OP, Nkot BP, Che J: Relationship between pro-and anti-inflammatory cytokines profiles and some haematological parameters in some Cameroonians infected with Onchocerca volvulus. Asian Pac J Trop Med 5(9): 713-717, 2012 66. Oh YH, Jeong SR, Kim JH, Song KJ, Kim K, Park S, Sohn S, Shin HJ:

Cytopathic changes and pro-inflammatory cytokines induced by Naegleria fowleri trophozoites in rat microglial cells and protective effects of an anti-Nfa1 antibody. Parasite Immunol 27(12): 453-459, 2005

67. Qvarnstrom Y, Visvesvara GS, Sriram R, da Silva AJ: Multiplex real-time PCR assay for simultaneous detection of Acanthamoeba spp. Balamuthia mandrillaris, and Naegleria fowleri. J Clin Microbiol 44(10): 3589-3595, 2006 68. Rezende-Oliveria K, Silva NM, Mineo JR, Rodrigues Junior V: Cytokine and

chemokines production by mononuclear cells from paturient woman after stimulation with live Toxoplasma gondii. Placenta 33(9): 682-687, 2012

69. Robinson BS, Monis PT, Dobsen PJ: Rapid, sensitive, and discriminating

identification of Naegleria spp. by real-time PCR and melting-curve analysis.

Appl Environ Microbiol 72(9): 5857-5863, 2006

70. Rojas-Bernabe A, Garcia-Hernamdez O, Maldonado-Bernal C, Delegado-Dominguez J, Ortega E, Gutierrez-Kobeh L, Beker I, Aguirre-Garcia M:

Leishmania mexicana lipophosphoglycan activate ERK and p38 MAP kinase and induces production of proinflammatory cytokines in human macrophages through TLR2 and TLR4. Parasitology 141(6): 788-800, 2014

71. Scheld WM, Whitley RJ, Durack DT: Infections of the central nervous system.

Raven Press, 43: 403-447, 1991

72. Schuster FL and Rechthand E: In vitro effects of amphotericin B on growth and ultrastructure of the amoeboflagellates Nagleria gruberi and Naegleria fowleri. Antimicrob Agents Chemother 8: 591-605, 1975

73. Schuster FL and Visvesvara GS: Amebae and ciliated protozoa as causal agents of waterborne zoonotic disease. Veter Parasitol 126(1-2): 91-120, 2004

74. Schuster FL and Visvesvara GS: Free-living amoebae as opportunistic and non-opportunistic pathogens of humans and animals. Int J Parasitol 34(9): 1001-1027, 2004

75. Schuster FL, Guglielmo BJ, Visvesvara GS: In-vitro activity of miltefosine and voriconazole in clinical isolates of free-living amebas: Balamuthia mandrillaris, Acanthamoeba spp., and Naegleria fowleri. J Eukaryot Microbiol 53: 121-126, 2006

76. Sedgwick JD, Schwender S, Gregersen R, Dorries R: Resident macrophages (ramified microglia) of the adult brown norway rat central nervous system are constitutively major histocompatibility complex class II positive. J Exp Med 177: 1145, 1993

77. Shakoor S, Beg MA, Mahmood SF, Bandea R, Sriram R, Noman F, Visvesvara GS, Zafar A: Primary amoebic meningoencephalitis caused by Naegleria fowleri, Karachi, Pakistan. Emerg Infect Dis 17(2): 258-61, 2011

78. Shin HJ, Cho MS, Jung SU, Kim HI, Park S, Kim HJ, Im KI: Molecular cloning and characterization of a gene encoding a 13.1 kDa antigenic protein of Naegleria fowleri. J Eukaryot Microbiol 48(6): 713-717, 2001

79. Sierra A, Gottfried-Blackmore AC, McEwen BS, Bulloch K: Microglia derived from aging mice exhibit an altered inflammatory profile. Glia 55(4): 412-424, 2007

80. Sleigh MA: Protozoa and other protists. Edward Arnold, London, UK 3429, 1989

81. Sohn HJ, Kim JH, Shin MH, Song KJ, Shin HJ: The Nf-actin gene is an important factor for food-cup formation and cytotoxicity of pathogenic Naegleria fowleri. Parasitol Res 106(4): 917-924, 2010

82. Song KJ, Song KH, Kim JH, Sohn HJ, Lee YJ, Park JE, Shin HJ: Heat shock protein 70 of Naegleria fowleri is important factor for proliferation and in vitro cytotoxicity. Parasitol Res 103(2): 313-317, 2008

83. Song KJ, Jeong SR, Park S, Kwon MH, Im KI, Pak JH, Shin HJ: Naegleria fowleri: functional expression of the Nfa1 protein in transfected Naegleria gruberi by promoter modification. Exp Parasitol 112(2):115-120, 2006

84. Steele C, Fidel PL Jr: Cytokine and chemokine production by human oral and vaginal epithelial cells in response to Candida albicans. Infect Immun 70(2):

577-583, 2002

85. Suzumura A, Sawada M, Yamamoto H, Marrunouchi T: Transforming growth factor-β suppresses activation and proliferation of microglia in vitro. J Immunol 151: 2150-2158, 1993

86. Townsend GC and Scheld WM: Infections of the celtral nervous system. Adv Intern Med 43: 403-447, 1998

87. Visvesvara GS: Amebic meningoencephalitides and keratitis: challenges in dignosis and treatment. Curr Opin Infect Dis 23: 590-594, 2010

88. Wood P: Neuroinflammation: Mechanisms and Management. Humana Press, 375, 2998

89. Yang Z and Panjwani N: Pathogenesis of Acanthamoeba keratitis:

carbohydrate mediated host-parasite interactions. Infect Immun 65: 439-445, 1997

90. Yoder JS, Eddy BA, Visvesvara GS, Capewell L, Beach MJ: The epidemiology of primary amoebic memingoencephalitis in the USA, 1962-2008. Epidemiol Infect 138(7): 968-975

91. Zielasek J, Archelos JJ, Toyka KV, Hartung HP: Expression of intercellular adhesion molecule-1 on rat microglial cells. Neurosci Lett 153: 136, 1993

파울러자유아메바 배설-분비 단백질의 작용 기작은 정확히 밝혀지지 않 은 상태이다. 이 연구에서는 파울러자유아메바 배설-분비 단백질에 의 해 표적세포에서 유도되는 염증 반응의 변화를 관찰하여, 원발성 아메바 성 수막뇌염을 야기하는 파울러자유아메바의 비접촉성 병인기전을 이해 하고자 하였다. 파울러자유아메바의 배설-분비 단백질에 의해 표적세포 로 사용된 BV2 마이크로글리아 세포에서 부분적으로 IL-1α 과 TNF-α 과 같은 몇몇 사이토카인의 발현이 증가하였고, 이 사이토카 인들의 발현은 MAPKs (Mitogen activated protein kinase) 경로에 의 해 매개되었다. 이런 연구 결과에서 파울러자유아메바의 배설-분비 단 백질은 BV2 마이크로글리아 세포에서 MAPKs 신호 전달 경로를 경유 하여 염증 반응을 유도하고 파울러자유아메바에 의한 원발성 아메바성 수막뇌염 유도시 비접촉성 병인 기전에 중요한 역할을 할 것으로 생각 된다.

Keywords: 파울러자유아메바, 단백분해효소, 배설-분비 단백질,

원발성 아메바성 수막뇌염, 사이토카인, 신경소교세포, MAPK 신호전달

PART II

A novel cathepsin B and cathepsin B-like cysteine protease from Naegleria fowleri excretory secretory proteins

and their biochemical properties

I. Introduction

A. ESP in Naegleria fowleri

Naegleria fowleri is a free-living amoeba, which causes acute, fulminating, hemorrhagic primary amoebic meningoencephalitis (PAM) in healthy children and young adults. N. fowleri has been isolated from freshwater lakes, hot springs, chlorinated swimming pools and soil (Cerva, 1971; Brown et al., 1983; Kyle and Noblet, 1985; Marciano-cabral and Cabral, 2007). A characteristic of PAM is the rapid onset of symptoms following exposure. N. fowleri trophozoites migrate to the brain tissue, meninges, and CSF through the olfactory bulb by penetrating the nasal epithelium (Ma et al., 1990). The disease progresses rapidly, and without prompt diagnosis and intervention, death usually occurs within one week or earlier (Visvesvara et al., 2007).

Elucidation of pathogenicity-related factors in N. fowleri is important for understanding the mechanism of parasite-host interactions in PAM. Amoebic pathogenicity may be resulted by complex processes including contact-dependent and contact-independent mechanisms, both which lead to host cell death. In previous studies, several agents have been reported that they are involved in the contact-dependent pathogenic mechanism of N. fowleri pathogenic related factors such as the Nfa1 protein, Heat shock protein 70, and Nf-actin, by participating in

the formation of phagocytic food-cup (Song et al., 2006; Song et al., 2008; Sohn et al., 2010).

In the contact-independent mechanism, the phospholipase A and B activity or a cytolytic factor causing destruction of cell membranes, the neuraminidase or elastase activity facilitating destruction of tissue culture cells, a perforin-like, pore-forming protein that lyses target cells, and the presence of a cytopathic protein within Naegleria amoebae that triggers the apoptosis pathway in susceptible tissue culture cells, were induced in amoebic pathogenesis (Schuster and Visvesvara, 2004; Marciano-Cabral and Cabral, 2007).

The excretory/secretory proteins of parasite are related with pathogenicity in contact-independent mechanism. The important roles for parasites ESP in pathobiological events of parasitic organisms have been largely addressed.

Echinococcus granulosus secretes a protein, which inhibits neutrophil chemotaxis and thereby affects the function of host cells (Shepherd et al., 1991). The excreted/secreted antigens of Toxoplasma gondii play critical roles in the regulation of host’s immune responses and induce protective immune responses in the hosts (Darcy et al., 1988), which collectively suggest that these antigens are attractive candidates for the development of vaccine against toxoplasmosis. N. fowleri also secrets large number of proteins into outside of the parasite and these proteins may play various pathobiological functions required for survival of the parasite and host-parasite interactions. Treatment of Nf-EPSs to Chinese hamster ovary (CHO)

cells resulted in cytotoxic effect (Lee et al., 2012). It was also reported that Nf-ESPs may play a critical role for host cell invasion by the parasite. Nf-Nf-ESPs also degraded host immunoglobulins, which suggesting its possible role in host immune evasion for parasite survival in the host (Kim et al., 2008; Kim et al., 2009).

However, only limited information on the nature of Nf-ESPs and biological roles of each component in the ESP is currently available. And therefore, characterization of biological and functional properties of the Nf-EPSs would be important to understand the pathobiogical events occurred by the parasite infection.

B. Cysteine proteases

Cysteine proteases, also known as thiol proteases, are ubiquitous enzymes that found in all living organisms from viruses to mammals. They are involved in diverse biological events in the organisms and play pivotal roles for the maintenance of homeostasis and survival of the organisms. They are classified into 14 superfamilies and several currently unassigned families based on MEROPS classification criteria, but they share a common catalytic mechanism, in which the sulphur atom of a cysteine residue in a catalytic triad or dyad acts as an attacking nucleophile (Smooker et al., 2010). Also, a histidine side chain is involved in a hydrogen acceptor/shuttle role. They are usually synthesized as preproenzymes, which are comprised with an N-terminal signal peptide, a prodomain, and a mature

domain. The N-terminal signal peptide directs the proteins into secretory vesicles, where they are stored in an inactive form due to the presence of the propeptide that binds to the active site pocket of mature domain and blocks enzyme activity. On release into their final working sites or places, the enzymes are activated via autocatalytic activation process. Meanwhile, some cysteine proteases require other proteases, which trim amino acids from the N-terminus of the mature domain, to

문서에서 Characterization of cathepsin B cysteine protease from Naegleria fowleri excretory-secretory proteins exerting immunomodulatory effects (페이지 50-74)