Journal: International Journal of Molecular Sciences
Article Title: N-Terminal Acetyltransferase Naa40p Whereabouts Put into N-Terminal Proteoform Perspective
doi: 10.3390/ijms22073690
Figure Lengend Snippet: Alternative splicing or alternative translation can give rise to hNaa40 S expression. ( A ) Scheme depicting two alternatively spliced h NAA40 transcripts; being transcript ENST00000377793.9 (3649 bp, transcript expected to code for the main functional isoform with transcript support level 1 according to the APPRIS database ( http://appris.bioinfo.cnio.es , accessed on 1 December 2020)) and transcript ENST00000542163.1 (1035 bp, transcript support level 2). Exons are indicated as boxes and corresponding non-coding and coding regions colored grey and orange, respectively. When considering the longest transcript, hNaa40 L and hNaa40 S translation initiates at the first (black arrow) and second in-frame AUG codon (orange arrow), respectively. Exon 1 encodes for the first 2 amino acids of hNaa40 L . The protein sequence of hNaa40 L (aa 1-237) with an indication of corresponding secondary structure elements of structure PDB:4U9V is provided above the transcripts. ( B ) Codon alignment of representative mammalian genomic sequences (alignment set hg38_58) in the vicinity of the canonical, database-annotated AUG TIS (dbTIS) (matching the human chr11:63939079-63939102 sequence indicated below) and the downstream AUG TIS (dTIS) (chr11:63945879-63945917 in human) of the NAA40 locus using WebLogo. The heights of the nucleotides are indicative for their degree of conservation at the indicated position . ( C ) Autoradiograph showing translation initiation of in vitro transcribed h NAA40 at the AUG start codons encoding M1 (black arrowhead) and M22 (dashed arrowhead). For this, wild type (1) and a dTIS mutagenized (mutation of ATG encoding M22 to CTG (dTIS > CTG)) h NAA40 pOTB7 constructs were in vitro transcribed and translated, and radiolabeled proteins visualized by radiography following sodium dodecyl sulfate (SDS)-PAGE and electroblotting.
Article Snippet: A sequence-verified full-length I.M.A.G.E. cDNA clone of h NAA40 (matching mRNA gi:13376118, cDNA clone MGC:59726, IMAGE:6292760)) cloned in the pOTB7 vector (IRAUp969D10104D, RZPD Imagenes, Germany) served as template for site-directed PCR-mutagenesis (QuickChange, Stratagene, La Jolla, CA, USA) according to the manufacturer’s instructions and as described in [ ] and using the primer pairs (10 nmol, RP-cartridge Gold, Eurogentec) Naa40a120c forward: 5′-GGAGCGAGCAGCCCTGGATGCCGTTTG-3′ and Naa40a120c reverse: 5′-CAAACGGCATCCAGGGCTGCTCGCTCC-3′ to introduce an ATG to CTG mutation of the newly identified dTIS in the coding sequence of h NAA40 , concomitantly resulting in recoding of Met22 to Leu. pMET7 Flag-tagged hNaa40p expressing constructs encoding either wild type full-length and thus also potential short hNaa40p (hNaa40 L/S ), hNaa40p with mutation of the dTIS (hNaa40 L(dTIS>CTG) ) or mutation of the dbTIS (hNaa40 S(dbTIS>CTG) ), in addition to the shorter hNaa40 S coding sequence (CDS) were generated using standard ApaI and SalI-HF restriction cloning and ligation.
Techniques: Expressing, Functional Assay, Sequencing, Genomic Sequencing, Autoradiography, In Vitro, Mutagenesis, Construct, SDS Page