This enzyme specifically removes a 32-amino acid peptide from the C-terminus of the precursor of the large subunit of hydrogenase 3 in Escherichia coli by cleavage at the C-terminal side of Arg537.
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REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
This enzyme specifically removes a 32-amino acid peptide from the C-terminus of the precursor of the large subunit of hydrogenase 3 in Escherichia coli by cleavage at the C-terminal side of Arg537.
the final step of maturation of [NiFe]-hydrogenases involves the activity of an endopeptidase which removes an oligopeptide from the C-terminus of the large subunit. The proteolytic maturation is followed by a conformational change, closing of the metal centre, its assembly with the small hydrogenase subunit and finally in the appearance of enzyme activity. HycI is specific for hydrogenase 3 maturation
cleavage occurs at the C-terminal side of the Arg537 (removal of a 32-amino acid peptide from the C-terminus). Nickel incorporation into the HYCE precursor is a prerequisite for processing
HycI involved in the C-terminal processing of HycE (UniProt: A1AER2), the large subunit of the hydrogenase 3 from Escherichia coli. Mutational alteration of the amino acid residues neighbouring the cleavage site shows that proteolysis still occurs when chemically similar amino acids are exchanged. Processing is blocked in a variant in which the methionine at the C-terminal side is replaced by a glutamate residue. Truncation of the precursor from the C-terminal end renders variants amenable to maturation even when two-thirds of the extension are removed but abolishes proteolysis upon further deletion of a cluster of six basic amino acids. A construct in which the C-terminal extension from the large subunit of the hydrogenase 2 is fused to the mature part of the large subunit of hydrogenase 3 is neither processed by HycI nor by HybD, the endopeptidase specific for the large subunit of hydrogenase 2
i.e. HycE (UniProt: A1AER2). Cleavage of HycE is specific in that the maturation of the large subunits of hydrogenases 1 and 2 is not affected in strains lacking hycl
the final step of maturation of [NiFe]-hydrogenases involves the activity of an endopeptidase which removes an oligopeptide from the C-terminus of the large subunit. The proteolytic maturation is followed by a conformational change, closing of the metal centre, its assembly with the small hydrogenase subunit and finally in the appearance of enzyme activity. HycI is specific for hydrogenase 3 maturation
HycI shows an open conformation at the putative nickel-binding site. Ni2+ has lower binding affinity with HycI than that of Cd2+, which is likely required for HycI to dissociate from HycE after the C-terminal processing
the reaction requires nickel to be bound to the precursor and the protease does not have a function in nickel delivery to the substrate. Radioactive labelling of cells with 63Ni, devoid of endopeptidase, resolves several forms of the precursor which are possibly intermediates in the maturation pathway. The endopeptidase uses the metal in the large subunit of [NiFe]-hydrogenases as a recognition motif
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CRYSTALLIZATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
solution structure of Escherichia coli HycI determined by high resolution nuclear magnetic resonance spectroscopy. The overall structure is similar to the crystal structure of holo-HybD in the same family. HycI shows an open conformation at the putative nickel-binding site, whereas HybD adopts a closed conformation
Solution structure and backbone dynamics of an endopeptidase HycI from Escherichia coli: implications for mechanism of the [NiFe] hydrogenase maturation
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3.4.23.51 HycI peptidase
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