3.4.11.26: intermediate cleaving peptidase 55
This is an abbreviated version!
For detailed information about intermediate cleaving peptidase 55, go to the full flat file.
Reaction
The enzyme cleaves the Pro36-Pro37 bond of cysteine desulfurase (EC 2.8.1.7) removing three amino acid residues (Tyr-Ser-Pro) from the N-terminus after cleavage by mitochondrial processing peptidase. =
Synonyms
At1g09300, Icp55, YER078c
ECTree
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Substrates Products on EC 3.4.11.26 - intermediate cleaving peptidase 55
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SUBSTRATE 
PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
FSTPSDLDSELTR + H2O
STPSDLDSELTR + Phe
N-terminal peptide of protein Oxa1
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-
?
FTSEAAADGGQDQILSR + H2O
TSEAAADGGQDQILSR + Phe
N-terminal peptide of mitochondrial acyl carrier protein 3
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-
?
Isa2 + H2O
?
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-
substrate is likely processed by isoform Icp55 in two consecutive steps, in which Icp55 removes two destabilizing amino acids: first Phe and then in a second round of processing Tyr, resulting in the mature stable protein
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?
SSLPSEAVDEK + H2O
SLPSEAVDEK + Ser
N-terminal peptide of protein At4g37930
-
-
?
Tyr-Ser-Pro-Nfs1 + H2O
Nfs1 + Tyr-Ser-Pro
the enzyme is involved in the processing pathway of yeast Nfs1 during its translocation into the mitochondrial matrix. Nfs1 from Saccharomyces cerevisiae undergoes two steps of proteolytic processing: first the mitochondrial processing peptidase (MPP) cleaves the precursor between Phe33 and Tyr34. Then Icp55 cleaves between Pro36 and Pro37 removing three amino acids residues (Tyr-Ser-Pro)
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-
?
Tyr-Ser-Pro-Nfs1 + H2O
Nfs1 + Tyr-Ser-Pro
the enzyme is involved in the processing pathway of yeast Nfs1 during its translocation into the mitochondrial matrix. Nfs1 from Saccharomyces cerevisiae undergoes two steps of proteolytic processing: first the mitochondrial processing peptidase (MPP) cleaves the precursor between Phe33 and Tyr34. Then Icp55 cleaves between Pro36 and Pro37 removing three amino acids residues (Tyr-Ser-Pro). In the absence of Nfs1 processing by mitochondrial processing peptidase (MPP), the Nfs1 precursor is not cleaved by Icp55. The two prolines are of importance for the Icp55 cleavage reaction, because the replacement of a single proline changes the specificity to a new cleavage site without eliminating the cleavage reaction per se
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-
?
additional information
?
-
enzyme is able to remove N-terminal amino acids L, Y, I, F, C, M of mitochondrial proteins
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?
additional information
?
-
Icp55 is critical for stabilization of the mitochondrial proteome. Icp55 removes an amino acid from a characteristic set of N-termini of preprotein intermediates generated by mitochondrial processing peptidase. Thereby Icp55 converts instable intermediates into stable proteins
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?
additional information
?
-
global analysis of the N-proteome of yeast mitochondria, revealing the N-termini of 615 different proteins. The N-proteome of icp55DELTA mitochondria yielded proteins whose N-terminus differs by one residue from the mature N-terminus of wild-type mitochondria. Icp55 cleaves between the last amino acid of the presequence (tyrosine, leucine or phenylalanine) and the first residue of the mature protein, preferentially serine, alanine and threonine. The most frequent residue tyrosine is efficiently removed by Icp55 and thus is the best substrate of Icp55. The efficiency of cleavage is lower for leucine and phenylalanine
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?
additional information
?
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-
identification of 36 substrates utilizing charge-based fractional diagonal chromatography, enabling the differential quantitation of 1459 nonredundant N-terminal peptides between two Saccharomyces cerevisiae samples within 10 h of LC-MS, starting from only 50 microg of protein per condition and analyzing only 40% of the obtained fractions
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?
additional information
?
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residue Tyr is preferred at P1 position. The enzyme additionally displays Xaa-Pro aminopeptidase activity in vitro
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?
additional information
?
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the enzyme is active towards substrates with proline at P1' position (M-/-PA and Y-/-PA). Icp55 cleaves off bulky residues from N-termini of proteins. Active towards substrates Y-/-AA, Y-/-TA and Y-/-SA
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?
additional information
?
-
residue Tyr is preferred at P1 position. The enzyme additionally displays Xaa-Pro aminopeptidase activity in vitro
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?
