title: Human Naa50 Protein Displays Broad Substrate Specificity for Amino-terminal Acetylation: DETAILED STRUCTURAL AND BIOCHEMICAL ANALYSIS USING TETRAPEPTIDE LIBRARY.
abstract: Amino-terminal acetylation is a critical co-translational modification of the newly synthesized proteins in a eukaryotic cell carried out by six amino-terminal acetyltransferases (NATs). All NATs contain at least one catalytic subunit, and some contain one or two additional auxiliary subunits. For example, NatE is a complex of Naa10, Naa50, and Naa15 (auxiliary). In the present study, the crystal structure of human Naa50 suggested the presence of CoA and acetylated tetrapeptide (AcMMXX) that have co-purified with the protein. Biochemical and thermal stability studies on the tetrapeptide library with variations in the first and second positions confirm our results from the crystal structure that a peptide with Met-Met in the first two positions is the best substrate for this enzyme. In addition, Naa50 acetylated all MXAA peptides except for MPAA. Transcriptome analysis of 10 genes that make up six NATs in humans from eight different cell lines suggests that components of NatE are transcribed in all cell lines, whereas others are variable. Because Naa10 is reported to acetylate all amino termini that are devoid of methionine and Naa50 acetylates all other peptides that are followed by methionine, we believe that NatE complex can be a major contributor for amino-terminal acetylation at the ribosome exit tunnel.
authors.affiliation: From the Centre for Chemical Biology and.
authors.forename: Ravikumar
authors.initials: R
authors.lastname: Reddi
authors.affiliation: From the Centre for Chemical Biology and.
authors.forename: Venkateshwarlu
authors.initials: V
authors.lastname: Saddanapu
authors.affiliation: National Centre for Mass Spectrometry, Council of Scientific and Industrial Research-Indian Institute of Chemical Technology, Hyderabad, Telangana 500 607, India.
authors.forename: Dinesh Kumar
authors.initials: DK
authors.lastname: Chinthapalli
authors.affiliation: From the Centre for Chemical Biology and.
authors.forename: Priyanka
authors.initials: P
authors.lastname: Sankoju
authors.affiliation: National Centre for Mass Spectrometry, Council of Scientific and Industrial Research-Indian Institute of Chemical Technology, Hyderabad, Telangana 500 607, India.
authors.forename: Prabhakar
authors.initials: P
authors.lastname: Sripadi
authors.affiliation: From the Centre for Chemical Biology and anthony@iict.res.in.
authors.forename: Anthony
authors.initials: A
authors.lastname: Addlagatta
mesh_terms: D000072283:A549 Cells; D000107:Acetylation; D057809:HEK293 Cells; D006801:Humans; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism; D063209:N-Terminal Acetyltransferase A / Q000235:genetics / Q000378:metabolism; D063213:N-Terminal Acetyltransferase E / Q000235:genetics / Q000378:metabolism*; D009842:Oligopeptides / Q000737:chemistry*; D019151:Peptide Library; D013379:Substrate Specificity
chemical_list: D009097:Multienzyme Complexes; C463022:NAA15 protein, human; D009842:Oligopeptides; D019151:Peptide Library; D063209:N-Terminal Acetyltransferase A; C504824:NAA10 protein, human; D063213:N-Terminal Acetyltransferase E; C520714:NAA50 protein, human
keywords: acetyltransferase; enzyme kinetics; peptides; protein stability; protein structure