Welcome To Website IAS

Hot news
Achievement

Independence Award

- First Rank - Second Rank - Third Rank

Labour Award

- First Rank - Second Rank -Third Rank

National Award

 - Study on food stuff for animal(2005)

 - Study on rice breeding for export and domestic consumption(2005)

VIFOTEC Award

- Hybrid Maize by Single Cross V2002 (2003)

- Tomato Grafting to Manage Ralstonia Disease(2005)

- Cassava variety KM140(2010)

Centres
Website links
Vietnamese calendar
Library
Visitors summary
 Curently online :  7
 Total visitors :  8650490

Leaky ribosomal scanning enables tunable translation of bicistronic ORFs in green algae
Saturday, 2025/03/08 | 07:13:34

Marco A. DueñasRory J. CraigSean D. Gallaher, and Sabeeha S. Merchant

PNAS; Feb. 26 2025; 122 (9) e2417695122; https://doi.org/10.1073/pnas.2417695122

Significance

Textbook dogma states that nucleus-encoded genes are monocistronic, producing transcripts with a single translated open reading frame (ORF). However, highly conserved bicistronic loci are pervasive in green algae that are separated by several hundred million years of evolution, speaking to their ancestral origins and functions within the Chlorophyte lineage. A combination of bioinformatic analysis and in vivo gene manipulation supports leaky ribosomal scanning as the primary mechanism for translation of more than one ORF from bicistronic transcripts. We have successfully tuned synthesis levels of two proteins encoded on one mRNA by modifying the ORF 1 Kozak-like sequence and limiting the number of AUG codons upstream of ORF 2. These findings may have broad applications in synthetic biology.

Abstract

Advances in sequencing technology have unveiled examples of nucleus-encoded polycistrons, once considered rare. Exclusively polycistronic transcripts are prevalent in green algae, although the mechanism by which multiple polypeptides are translated from a single transcript is unknown. Here, we used bioinformatic and in vivo mutational analyses to evaluate competing mechanistic models for translation of bicistronic mRNAs in green algae. High-confidence manually curated datasets of bicistronic loci from two divergent green algae, Chlamydomonas reinhardtii and Auxenochlorella protothecoides, revealed a preference for weak Kozak-like sequences for ORF 1 and an underrepresentation of potential initiation codons before the ORF 2 start codon, which are suitable conditions for leaky ribosome scanning to allow ORF 2 translation. We used mutational analysis in A. protothecoides to test the mechanism. In vivo manipulation of the ORF 1 Kozak-like sequence and start codon altered reporter expression at ORF 2, with a weaker Kozak-like sequence enhancing expression and a stronger one diminishing it. A synthetic bicistronic dual reporter demonstrated inversely adjustable activity of green fluorescent protein expressed from ORF 1 and luciferase from ORF 2, depending on the strength of the ORF 1 Kozak-like sequence. Our findings demonstrate that translation of multiple ORFs in green algal bicistronic transcripts is consistent with episodic leaky scanning of ORF 1 to allow translation at ORF 2. This work has implications for the potential functionality of upstream open reading frames (uORFs) found across eukaryotic genomes and for transgene expression in synthetic biology applications.

 

See https://www.pnas.org/doi/10.1073/pnas.2417695122

 

Figure 1: Bicistronic loci in divergent green algae. (A) 36 bicistronic loci in C. reinhardtii are conserved in field isolates. Translation of both ORFs is supported by Ribo-Seq data. Orthologous bicistronic transcripts were identified in other Chlorophytes. High confidence hits and evidence of colinearity were further evaluated (Materials and Methods). Yellow denotes a colinear pair of ORFs with significant similarity to a pair of bicistronic ORFs from C. reinhardtii. Red and orange, respectively, indicate additional support with Iso-Seq or EST data. Columns are ordered by the phylogenetic tree above each panel. Species abbreviations (From leftmost to rightmost column) are as follows: Mpu, Micromonas. pusilla; Olu, Ostreococcus lucimarinus; Csu, Coccomyxa subellipsoidea; Czo, Chromochloris zofingiensis; Dsa, Dunaliella salina; Vca, Volvox carteri. (B) 43 bicistronic loci were identified in A. protothecoides. A similar search for orthologs was performed as described in panel A but restricted to the Trebouxiophyceae with C. reinhardtii as an outgroup. Species abbreviations (from leftmost to rightmost column) are as follows: Cre, Chlamydomonas reinhardtii; Csu, Coccomyxa subellipsoidea; Nde, Nannochloris desiccata; Cvu, Chlorella vulgaris; Cso, Chlorella sorokiniana; Pcu, Prototheca cutis.

Back      Print      View: 65

[ Other News ]___________________________________________________
  • Host plant resistance for fall armyworm management in maize: relevance, status and prospects in Africa and Asia
  • Increasing plant group productivity through latent genetic variation for cooperation
  • THP9 enhances seed protein content and nitrogen-use efficiency in maize
  • The role of soybean 14-3-3 gene (Glyma05g29080) on white mold resistance and nodulation investigations using CRISPR-Cas9 editing and RNA silencing
  • Progress in Soybean Genetic Transformation Over the Last Decade
  • Climate change challenges plant breeding
  • Breeding for disease resistance in soybean: a global perspective
  • The phosphorylation of AMPKβ1 is critical for increasing autophagy and maintaining mitochondrial homeostasis in response to fatty acids
  • Genomic selection for spot blotch in bread wheat breeding panels, full-sibs and half-sibs and index-based selection for spot blotch, heading and plant height
  • Response of Southeast Asian rice root architecture and anatomy phenotypes to drought stress
  • Root Pulling Force Across Drought in Maize Reveals Genotype by Environment Interactions and Candidate Genes
  • Root hair-specific transcriptome reveals response to low phosphorus in Cicer arietinum
  • Protocol for targeted modification of the rice genome using base editing
  • Understanding the Dynamics of Blast Resistance in Rice- Magnaporthe oryzae Interactions
  • Multi-omics analysis reveals the mechanism of seed coat color formation in Brassica rapa L.
  • Highly efficient transgene-free genome editing in tobacco using an optimized CRISPR/Cas9 system, pOREU3TR
  • Breeding of Rc Function Restoration Red Rice via CRISPR/Cas9 Mediated Genome Editing
  • Transposon insertions within alleles of BnaFT.A2 are associated with seasonal crop type in rapeseed
  • Natural allelic variation of GmST05 controlling seed size and quality in soybean
  • Cassava mosaic disease and its management in Southeast Asia

 

Designed & Powered by WEBSO CO.,LTD