@article{1299949,

title = {Enzyme-catalyzed expressed protein ligation},

author = {Samuel H Henager and Nam Chu and Zan Chen and David Bolduc and Daniel R Dempsey and Yousang Hwang and James Wells and Philip A Cole},

doi = {10.1038/nmeth.4004},

issn = {1548-7105},

year  = {2016},

date = {2016-11-01},

journal = {Nat Methods},

volume = {13},

number = {11},

pages = {925-927},

abstract = {Expressed protein ligation is a valuable method for protein semisynthesis that involves the reaction of recombinant protein C-terminal thioesters with N-terminal cysteine (N-Cys)-containing peptides, but the requirement of a Cys residue at the ligation junction can limit the utility of this method. Here we employ subtiligase variants to efficiently ligate Cys-free peptides to protein thioesters. Using this method, we have more accurately determined the effect of C-terminal phosphorylation on the tumor suppressor protein PTEN.},

keywords = {Animals, Bacillus subtilis, Blotting, Catalytic Domain, Cells, Cultured, Cysteine, Escherichia coli, Fibroblasts, Mice, Mutagenesis, Peptide Fragments, Peptide Synthases, Phosphorylation, Post-Translational, Protein Processing, PTEN Phosphohydrolase, Recombinant Proteins, Site-Directed, Subtilisins, Western},

pubstate = {published},

tppubtype = {article}

}

@article{1299971,

title = {Synthetic approaches to protein phosphorylation},

author = {Zan Chen and Philip A Cole},

doi = {10.1016/j.cbpa.2015.07.001},

issn = {1879-0402},

year  = {2015},

date = {2015-10-01},

journal = {Curr Opin Chem Biol},

volume = {28},

pages = {115-22},

abstract = {Reversible protein phosphorylation is critically important in biology and medicine. Hundreds of thousands of sites of protein phosphorylation have been discovered but our understanding of the functions of the vast majority of these post-translational modifications is lacking. This review describes several chemical and biochemical methods that are under development and in current use to install phospho-amino acids and their mimics site-specifically into proteins. The relative merits of total chemical synthesis, semisynthesis, and nonsense suppression strategies for studying protein phosphorylation are discussed in terms of technical simplicity, scope, and versatility.},

keywords = {Animals, Humans, Mutagenesis, Phosphoproteins, Phosphorylation, Protein Transport, Recombinant Proteins, Site-Directed},

pubstate = {published},

tppubtype = {article}

}

@article{1299977,

title = {Regulation of S-adenosylhomocysteine hydrolase by lysine acetylation},

author = {Yun Wang and Jennifer M Kavran and Zan Chen and Kannan R Karukurichi and Daniel J Leahy and Philip A Cole},

doi = {10.1074/jbc.M114.597153},

issn = {1083-351X},

year  = {2014},

date = {2014-11-01},

journal = {J Biol Chem},

volume = {289},

number = {45},

pages = {31361-72},

abstract = {S-Adenosylhomocysteine hydrolase (SAHH) is an NAD(+)-dependent tetrameric enzyme that catalyzes the breakdown of S-adenosylhomocysteine to adenosine and homocysteine and is important in cell growth and the regulation of gene expression. Loss of SAHH function can result in global inhibition of cellular methyltransferase enzymes because of high levels of S-adenosylhomocysteine. Prior proteomics studies have identified two SAHH acetylation sites at Lys(401) and Lys(408) but the impact of these post-translational modifications has not yet been determined. Here we use expressed protein ligation to produce semisynthetic SAHH acetylated at Lys(401) and Lys(408) and show that modification of either position negatively impacts the catalytic activity of SAHH. X-ray crystal structures of 408-acetylated SAHH and dually acetylated SAHH have been determined and reveal perturbations in the C-terminal hydrogen bonding patterns, a region of the protein important for NAD(+) binding. These crystal structures along with mutagenesis data suggest that such hydrogen bond perturbations are responsible for SAHH catalytic inhibition by acetylation. These results suggest how increased acetylation of SAHH may globally influence cellular methylation patterns.},

keywords = {Acetylation, Adenosylhomocysteinase, Amino Acid, Amino Acid Sequence, Catalysis, Crystallography, Humans, Hydrogen Bonding, Lysine, Methylation, Models, Molecular, Molecular Sequence Data, Mutagenesis, NAD, Plasmids, Post-Translational, Protein Binding, Protein Processing, Protein Structure, Recombinant Proteins, Sequence Homology, Site-Directed, Structure-Activity Relationship, Tertiary, X-Ray},

pubstate = {published},

tppubtype = {article}

}