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Peptide bond cleavage through cyclization of asparagine (768.4)
Author(s) -
Giaccone Zachary,
Urbanski Laura,
Siegart Nicolle,
Reitter Julie,
Mills Kenneth
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.768.4
Subject(s) - intein , asparagine , peptide bond , cleavage (geology) , chemistry , peptide , stereochemistry , residue (chemistry) , protein splicing , amino acid , combinatorial chemistry , biochemistry , rna splicing , biology , gene , paleontology , rna , fracture (geology)
Protein splicing is the post translational modification by which an internal peptide, or intein, separates itself from the surrounding residues, known as exteins. In the third step of the mechanism, asparagine cyclization, coupled to peptide bond cleavage, cleaves the intein from the neighboring exteins. We have studied this cyclization in two ways. The first is by a model peptide assay by which the cyclization of Asn is coupled to fluorescence. We observed that an increase of temperature correlates to a faster cyclization reaction, while a decrease in the dielectric of the solvent slows the cleavage of the peptide. The second way we studied cyclization is through the inteins from Trichodesmium erythraeum and Syncechococcus sp. PCC 6803 . The intein from T. erythraeum ends in a Gln as opposed to the highly conserved Asn. By making mutations to the last residues, Asn or Gln, we revealed that T. erythraeum intein can complete C‐terminal cleavage with either amino acid, whereas Syncechococcus sp. PCC 6803 requires the asparagine in order to cleave. This supports the hypothesis that a naturally occurring cyclization with Gln could also be completed if the residue was mutated to the more kinetically favorable Asn. However, it is unlikely that a natural Asn cyclization would be able to react in the same way if mutated to Gln. Grant Funding Source : Supported by the National Science Foundation under grant MCB‐1244089 and by the Dreyfus Foundation