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Activation of latent protease function of pro-hK2, but not pro-PSA, involves autoprocessing

Denmeade, Samuel R.; Lövgren, Janita LU ; Khan, Saeed R.; Lilja, Hans LU and Isaacs, John T. (2001) In The Prostate 48(2). p.122-126
Abstract
BACKGROUND: Human glandular kallikrein 2 (hK2) and prostate-specific antigen (PSA) are members of an extensive kallikrein family of proteases. Both proteases are secreted as zymogens or proenzymes containing a seven amino acid propeptide that must be proteolytically removed for enzymatic activation. The physiological proteases that activate pro-hK2 and pro-PSA are not known. METHODS: The pro-hK2 peptide sequence is Val-Pro-Leu-Ile-Gln-Ser-Arg (VPLIQSR). For PSA, the amino acid sequence of the propeptide is Ala-Pro-Leu-Ile-Leu-Ser-Arg (APLILSR). Fluorescent substrates were made by coupling these peptide sequences to 7-amino-4-methylcoumarin (AMC). The hydrolysis of the VPLIQSR-AMC and APLILSR-AMC substrates by hK2, PSA, and a panel of... (More)
BACKGROUND: Human glandular kallikrein 2 (hK2) and prostate-specific antigen (PSA) are members of an extensive kallikrein family of proteases. Both proteases are secreted as zymogens or proenzymes containing a seven amino acid propeptide that must be proteolytically removed for enzymatic activation. The physiological proteases that activate pro-hK2 and pro-PSA are not known. METHODS: The pro-hK2 peptide sequence is Val-Pro-Leu-Ile-Gln-Ser-Arg (VPLIQSR). For PSA, the amino acid sequence of the propeptide is Ala-Pro-Leu-Ile-Leu-Ser-Arg (APLILSR). Fluorescent substrates were made by coupling these peptide sequences to 7-amino-4-methylcoumarin (AMC). The hydrolysis of the VPLIQSR-AMC and APLILSR-AMC substrates by hK2, PSA, and a panel of purified proteases was determined. RESULTS: HK2 readily cleaved the pro-hK2 peptide substrate VPLIQSR-AMC with a rate of hydrolysis that was approximately 8-fold higher than an equimolar amount of purified trypsin. HK2 also had the highest hydrolysis rate from among a group of other trypsin-like proteases. In contrast, neither hK2 nor PSA was able to appreciably cleave the pro-PSA substrate APLILSR-AMC. The pro-PSA substrate was most readily hydrolyzed by urokinase and trypsin. CONCLUSIONS: HK2 can hydrolyze the pro-hK2 substrate suggesting that maturation of pro-hK2 to enzymatically active hK2 involves autoprocessing. As expected, PSA, a chymotrypsin-like protease, was unable to hydrolyze either of the propeptide substrates. Therefore, it is unlikely that PSA can auto-process its own enzymatic function. HK2 has trypsin-like specificity but was unable to hydrolyze the pro-PSA substrate. These results raise the possibility that an additional processing protease may be required to fully process PSA to an enzymatically active form. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
auto-processing, prostate cancer, prostate-specific antigen (PSA), human glandular kallikrein 2 (hK2), propeptide
in
The Prostate
volume
48
issue
2
pages
122 - 126
publisher
John Wiley & Sons
external identifiers
  • pmid:11433422
  • scopus:0035399462
ISSN
0270-4137
DOI
10.1002/pros.1088
language
English
LU publication?
yes
id
5c4928d3-9815-439c-ac23-07ecae26d510 (old id 1121870)
date added to LUP
2008-06-26 12:16:39
date last changed
2018-01-07 06:19:10
@article{5c4928d3-9815-439c-ac23-07ecae26d510,
  abstract     = {BACKGROUND: Human glandular kallikrein 2 (hK2) and prostate-specific antigen (PSA) are members of an extensive kallikrein family of proteases. Both proteases are secreted as zymogens or proenzymes containing a seven amino acid propeptide that must be proteolytically removed for enzymatic activation. The physiological proteases that activate pro-hK2 and pro-PSA are not known. METHODS: The pro-hK2 peptide sequence is Val-Pro-Leu-Ile-Gln-Ser-Arg (VPLIQSR). For PSA, the amino acid sequence of the propeptide is Ala-Pro-Leu-Ile-Leu-Ser-Arg (APLILSR). Fluorescent substrates were made by coupling these peptide sequences to 7-amino-4-methylcoumarin (AMC). The hydrolysis of the VPLIQSR-AMC and APLILSR-AMC substrates by hK2, PSA, and a panel of purified proteases was determined. RESULTS: HK2 readily cleaved the pro-hK2 peptide substrate VPLIQSR-AMC with a rate of hydrolysis that was approximately 8-fold higher than an equimolar amount of purified trypsin. HK2 also had the highest hydrolysis rate from among a group of other trypsin-like proteases. In contrast, neither hK2 nor PSA was able to appreciably cleave the pro-PSA substrate APLILSR-AMC. The pro-PSA substrate was most readily hydrolyzed by urokinase and trypsin. CONCLUSIONS: HK2 can hydrolyze the pro-hK2 substrate suggesting that maturation of pro-hK2 to enzymatically active hK2 involves autoprocessing. As expected, PSA, a chymotrypsin-like protease, was unable to hydrolyze either of the propeptide substrates. Therefore, it is unlikely that PSA can auto-process its own enzymatic function. HK2 has trypsin-like specificity but was unable to hydrolyze the pro-PSA substrate. These results raise the possibility that an additional processing protease may be required to fully process PSA to an enzymatically active form.},
  author       = {Denmeade, Samuel R. and Lövgren, Janita and Khan, Saeed R. and Lilja, Hans and Isaacs, John T.},
  issn         = {0270-4137},
  keyword      = {auto-processing,prostate cancer,prostate-specific antigen (PSA),human glandular kallikrein 2 (hK2),propeptide},
  language     = {eng},
  number       = {2},
  pages        = {122--126},
  publisher    = {John Wiley & Sons},
  series       = {The Prostate},
  title        = {Activation of latent protease function of pro-hK2, but not pro-PSA, involves autoprocessing},
  url          = {http://dx.doi.org/10.1002/pros.1088},
  volume       = {48},
  year         = {2001},
}