Transposable elements shape the human proteome landscape via formation of cis‐acting upstream open reading frames

Transposons are major drivers of mammalian genome evolution. To obtain new insights into the contribution of transposons to the regulation of protein translation, we here examined how transposons affected the genesis and function of upstream open reading frames (uORFs), which serve as cis‐acting elements to regulate translation from annotated ORFs (anORFs) located downstream of the uORFs in eukaryotic mRNAs. Among 39,786 human uORFs, 3,992 had ATG trinucleotides of a transposon origin, termed “transposon‐derived upstream ATGs” or TuATGs. Luciferase reporter assays suggested that many TuATGs modulate translation from anORFs. Comparisons with transposon consensus sequences revealed that most TuATGs were generated by nucleotide substitutions in non‐ATG trinucleotides of integrated transposons. Among these non‐ATG trinucleotides, GTG and ACG were converted into TuATGs more frequently, indicating a CpG methylation‐mediated process of TuATG formation. Interestingly, it is likely that this process accelerated human‐specific upstream ATG formation within transposon sequences in 5′ untranslated regions after divergence between human and nonhuman primates. Methylation‐mediated TuATG formation seems to be ongoing in the modern human population and could alter the expression of disease‐related proteins. This study shows that transposons have potentially been shaping the human proteome landscape via cis‐acting uORF creation.     

Reliability and Construct Validity of the Malay Version of Theory of Planned Behaviour (TPB) for Smoking Cessation

Objective: The aim of this study was to evaluate the psychometric properties of the Malay translated version ofthe Theory of Planned Behavior (TPB) intention to quit smoking questionnaire. Methods: A cross-sectional studywas performed involving 185 male smokers. The forward-backward translation procedure was adopted to translate thequestionnaire from English to Malay. The internal consistency and stability were assessed using Cronbach’s alpha and acorrelation analysis and Exploratory Factor Analysis was conducted. Result: The translated questionnaire showed goodinternal consistency with Cronbach’s alpha values of 0.86, 0.64, 0.74 and 0.90 for each of the four respective factors.The test-retest reliability revealed acceptable stability, with Spearman’s correlation coefficients ranging from low tomoderate (r>0.30-0.50) and a satisfactory inter class correlation coefficient (ICCs). The construct validity achieved anacceptable factor loading for each construct which ranged from 0.40 to 0.90. Conclusion: The current study providedpsychometric evidence for an appropriate, reliable and valid tool of TPB Malay version. This questionnaire could beapplied in evaluating smoking cessation interventions in Malaysia.     

Structural basis for TetM-mediated tetracycline resistance

Ribosome protection proteins (RPPs) confer tetracycline resistance by binding to the ribosome and chasing the drug from its binding site. The current model for the mechanism of action of RPPs proposes that drug release is indirect and achieved via conformational changes within the drug-binding site induced upon binding of the RPP to the ribosome. Here we report a cryo-EM structure of the RPP TetM in complex with the 70S ribosome at 7.2-Å resolution. The structure reveals the contacts of TetM with the ribosome, including interaction between the conserved and functionally critical C-terminal extension of TetM and the decoding center of the small subunit. Moreover, we observe direct interaction between domain IV of TetM and the tetracycline binding site and identify residues critical for conferring tetracycline resistance. A model is presented whereby TetM directly dislodges tetracycline to confer resistance.