scholarly journals Alternative translation initiation generates a functionally distinct isoform of the stress-activated kinase MK2

2018 ◽  
Author(s):  
Philipp Trulley ◽  
Goda Snieckute ◽  
Dorte Bekker-Jensen ◽  
Manoj B. Menon ◽  
Robert Freund ◽  
...  
Keyword(s):  
Gene Regulation ◽  
Translation Initiation ◽  
Specific Binding ◽  
Protein Isoforms ◽  
Early Gene ◽  
Start Codon ◽  
Start Site ◽  
Alternative Translation ◽  
Transcriptional Gene Regulation ◽  
Translation Initiation Start

AbstractShaping of the proteome by alternative translation is an important mechanism of post-transcriptional gene regulation. It can lead to the expression of multiple protein isoforms originating from the same mRNA. Here we show that a novel, abundant and long isoform of the stress/p38MAPK-activated kinase MK2, a key regulator of transcription, migration, death signaling and post-transcriptional gene regulation, is constitutively translated from an alternative CUG translation initiation start site located in the 5′UTR of its mRNA. GC-rich sequences and putative G-quadruplex structures influence the usage of that codon as a translation initiation start site and the RNA helicase eIF4A1 is needed to ensure alternative isoform translation. We recapitulated the usage of the alternative start codon and determined the molecular properties of the short and a long MK2 isoforms. Phenotypically, only the short isoform phosphorylated Hsp27, supported migration and stress-induced immediate early gene (IEG) expression. Interaction profiling by quantitative mass-spectrometry revealed short isoform-specific binding partners that were associated with migration. In contrast, the long isoform contains additional putative phosphorylation sites in its unique N-terminus. In sum, our data reveal a longer and previously non-described isoform of MK2 with distinct physiological properties originating from alternative translation.

scholarly journals AUGmenting the proteome: Novel initiation codons and their role in protein isoform generation

2015 ◽  
Vol 37 (2) ◽  
pp. 19-23
Author(s):  
Mark J. Coldwell ◽  
Joanne L. Cowan
Keyword(s):  
Alternative Splicing ◽  
Translation Initiation ◽  
Messenger Rna ◽  
Genetic Material ◽  
Protein Sequencing ◽  
Protein Isoforms ◽  
Alternative Promoters ◽  
Alternative Translation ◽  
Initial Hypothesis ◽  
Protein Isoform

As the field of molecular biology developed, and the understanding of how inherited genetic material results in the expression of proteins was established, the initial hypothesis was that one gene gave rise to one protein1. As researchers delved deeper into the organization of the genetic code and advances in messenger RNA (mRNA) and protein sequencing were subsequently made, it has become abundantly clear that multiple mechanisms exist meaning that many mRNAs encode more than one version of a protein. Although alternative promoters and alternative splicing play a considerable role in the generation of protein isoforms, in this article we discuss how usage of alternative translation initiation codons in eukaryotes can also lead to an expanded proteome.

scholarly journals Alternative Translation Initiation of a Haloarchaeal Serine Protease Transcript Containing Two In-Frame Start Codons

2016 ◽  
Vol 198 (13) ◽  
pp. 1892-1901 ◽  
Author(s):  
Wei Tang ◽  
Yufeng Wu ◽  
Moran Li ◽  
Jian Wang ◽  
Sha Mei ◽  
...  
Keyword(s):  
Serine Protease ◽  
Translation Initiation ◽  
Mutational Analysis ◽  
Start Codon ◽  
Translation Efficiency ◽  
Stem Loop ◽  
Alternative Translation Initiation ◽  
Content Type ◽  
Translation Start ◽  
Alternative Translation

ABSTRACTRecent studies have shown that haloarchaea employ leaderless and Shine-Dalgarno (SD)-less mechanisms for translation initiation of leaderless transcripts with a 5′ untranslated region (5′ UTR) of <10 nucleotides (nt) and leadered transcripts with a 5′ UTR of ≥10 nt, respectively. However, whether the two mechanisms can operate on the same naturally occurring haloarchaeal transcript carrying multiple potential start codons is unknown. In this study, the transcript of thesptAgene (encoding an extracellular serine protease ofNatrinemasp. strain J7-2) was experimentally determined and found to contain two potential in-frame AUG codons (AUG1and AUG2) located 5 and 29 nt, respectively, downstream of the transcription start site. Mutational analysis revealed that both AUGs can function as the translation start codon for production of active SptA, although AUG1is more efficient than AUG2for translation initiation. Insertion of a stable stem-loop structure between the two AUGs completely abolished initiation at AUG1but did not affect initiation at AUG2, indicating that AUG2-initiated translation does not involve ribosome scanning from the 5′ end of the transcript. Furthermore, the efficiency of AUG2-initiated translation was not influenced by an upstream SD-like sequence. In addition, both AUG1and AUG2contribute to transcript stability, probably by recruiting ribosomes to protect the transcript against degradation. These data suggest that depending on which of two in-frame start codons is used, thesptAtranscript can act as either a leaderless or a leadered transcript for SptA production in haloarchaea.IMPORTANCEIn eukaryotes and bacteria, alternative translation start sites contribute to proteome complexity and can be used as a functional mechanism to increase translation efficiency. However, little is known about alternative translation initiation in archaea. Our results demonstrate that leaderless and SD-less mechanisms can be used for translation initiation of thesptAtranscript from two in-frame start codons, raising the possibility that in haloarchaea, alternative translation initiation on one transcript functions to increase translation efficiency and/or contribute to proteome complexity.

Genetic selection for mutations that reduce or abolish ribosomal recognition of the HIS4 translational initiator region

1988 ◽  
Vol 8 (7) ◽  
pp. 2955-2963 ◽  
Author(s):  
T F Donahue ◽  
A M Cigan
Keyword(s):  
Translation Initiation ◽  
Genetic Selection ◽  
Start Codon ◽  
Direct Selection ◽  
Start Site ◽  
Functional Nature ◽  
Selection For ◽  
Sequence Requirements ◽  
Insight Into

A unique genetic selection was devised at the HIS4 locus to address the mechanism of translation initiation in Saccharomyces cerevisiae and to probe sequence requirements at the normal translational initiator region that might participate in ribosomal recognition of the AUG start codon. The first AUG codon at the 5' end of the HIS4 message serves as the start site for translation, and the -3 and +4 nucleotide positions flanking this AUG (AXXAUGG) correspond to a eucaryotic consensus start region. Despite this similarity, direct selection for mutations that reduce or abolish ribosomal recognition of this region does not provide any insight into the functional nature of flanking nucleotides. The only mutations identified that affected recognition of this region were alterations in the AUG start codon. Among 150 spontaneous isolates, 26 were shown to contain mutations in the AUG start codon, including all +1 changes (CUG, GUG, and UUG), all +3 changes (AUA, AUC, and AUU), and one +2 change (ACG). These seven mutations of the AUG start codon, as well as AAG and AGG constructed in vitro, were assayed for their ability to support HIS4 expression. No codon other than AUG is physiologically relevant to translation initiation at HIS4 as determined by growth tests and quantitated in his4-lacZ fusion strains. These data and analysis of other his4 alleles are consistent with a mechanism of initiation at HIS4 as proposed in the scanning model whereby the first AUG codon nearest the 5' end of the message serves as the start site for translation and points to the AUG codon in S. cerevisiae as an important component for ribosomal recognition of the initiator region.

scholarly journals Genetic selection for mutations that reduce or abolish ribosomal recognition of the HIS4 translational initiator region.

1988 ◽  
Vol 8 (7) ◽  
pp. 2955-2963 ◽  
Author(s):  
T F Donahue ◽  
A M Cigan
Keyword(s):  
Translation Initiation ◽  
Genetic Selection ◽  
Start Codon ◽  
Direct Selection ◽  
Start Site ◽  
Functional Nature ◽  
Selection For ◽  
Sequence Requirements ◽  
Insight Into

A unique genetic selection was devised at the HIS4 locus to address the mechanism of translation initiation in Saccharomyces cerevisiae and to probe sequence requirements at the normal translational initiator region that might participate in ribosomal recognition of the AUG start codon. The first AUG codon at the 5' end of the HIS4 message serves as the start site for translation, and the -3 and +4 nucleotide positions flanking this AUG (AXXAUGG) correspond to a eucaryotic consensus start region. Despite this similarity, direct selection for mutations that reduce or abolish ribosomal recognition of this region does not provide any insight into the functional nature of flanking nucleotides. The only mutations identified that affected recognition of this region were alterations in the AUG start codon. Among 150 spontaneous isolates, 26 were shown to contain mutations in the AUG start codon, including all +1 changes (CUG, GUG, and UUG), all +3 changes (AUA, AUC, and AUU), and one +2 change (ACG). These seven mutations of the AUG start codon, as well as AAG and AGG constructed in vitro, were assayed for their ability to support HIS4 expression. No codon other than AUG is physiologically relevant to translation initiation at HIS4 as determined by growth tests and quantitated in his4-lacZ fusion strains. These data and analysis of other his4 alleles are consistent with a mechanism of initiation at HIS4 as proposed in the scanning model whereby the first AUG codon nearest the 5' end of the message serves as the start site for translation and points to the AUG codon in S. cerevisiae as an important component for ribosomal recognition of the initiator region.

scholarly journals Quality control of 40S ribosome head assembly ensures scanning competence

2020 ◽  
Vol 219 (11) ◽  
Author(s):  
Haina Huang ◽  
Homa Ghalei ◽  
Katrin Karbstein
Keyword(s):  
Quality Control ◽  
Conformational Changes ◽  
Translation Initiation ◽  
Site Selection ◽  
Start Codon ◽  
Start Site ◽  
Genetic Analyses ◽  
Head Assembly ◽  
Control Step ◽  
Assembly Intermediate

During translation initiation, 40S ribosomes scan the mRNA until they encounter the start codon, where conformational changes produce a translation-competent 80S complex. Destabilizing the scanning complex results in misinitiation at non-AUG codons, demonstrating its importance for fidelity. Here, we use a combination of biochemical and genetic analyses to demonstrate that the ability of the nascent subunit to adopt the scanning complex is tested during assembly via structural mimicry. Specifically, formation of the 80S-like assembly intermediate, which structurally resembles scanning complexes, requires the correct folding of two rRNA elements in the subunit head and the proper positioning of the universally conserved head proteins Rps3, Rps15, Rps20, and Rps29. rRNA misfolding impairs the formation of 80S-like ribosomes, and bypass of individual checkpoints using cancer-associated mutations produces ribosomes defective in accurate start-site selection. Thus, the formation of 80S-like assembly intermediates is a quality control step that ensures scanning competence of the nascent subunit.

scholarly journals Distress Regulates Different Pathways in the Brain of Common Carp: A Preliminary Study

Animals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 585
Author(s):  
Alexander Burren ◽  
Constanze Pietsch
Keyword(s):  
Gene Regulation ◽  
Common Carp ◽  
Binding Protein ◽  
Principal Component ◽  
Brain Regions ◽  
Point Estimation ◽  
Early Gene ◽  
Important Species ◽  
Preliminary Study ◽  
The Brain

In this study, a stress trial was conducted with common carp, one of the most important species in aquaculture worldwide, to identify relevant gene regulation pathways in different areas of the brain. Acute distress due to exposure to air significantly activated the expression of the immediate early gene c-fos in the telencephalon. In addition, evidence for regulation of the two corticotropin-releasing factor (crf) genes in relation to their binding protein (corticotropin-releasing hormone-binding protein, crh-bp) is presented in this preliminary study. Inferences on the effects of due to exposure to air were obtained by using point estimation, which allows the prediction of a single value. This constitutes the best description to date of the previously generally unknown effects of stress in different brain regions in carp. Furthermore, principal component analyses were performed to reveal possible regulation patterns in the different regions of the fish brain. In conclusion, these preliminary studies on gene regulation in the carp brain that has been influenced by exposure to a stressor reveal that a number of genes may be successfully used as markers for exposure to unfavourable conditions.

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