title: Non-optimal codon usage affects expression, structure and function of clock protein FRQ.
abstract: Codon-usage bias has been observed in almost all genomes and is thought to result from selection for efficient and accurate translation of highly expressed genes. Codon usage is also implicated in the control of transcription, splicing and RNA structure. Many genes exhibit little codon-usage bias, which is thought to reflect a lack of selection for messenger RNA translation. Alternatively, however, non-optimal codon usage may be of biological importance. The rhythmic expression and the proper function of the Neurospora FREQUENCY (FRQ) protein are essential for circadian clock function. Here we show that, unlike most genes in Neurospora, frq exhibits non-optimal codon usage across its entire open reading frame. Optimization of frq codon usage abolishes both overt and molecular circadian rhythms. Codon optimization not only increases FRQ levels but, unexpectedly, also results in conformational changes in FRQ protein, altered FRQ phosphorylation profile and stability, and impaired functions in the circadian feedback loops. These results indicate that non-optimal codon usage of frq is essential for its circadian clock function. Our study provides an example of how non-optimal codon usage functions to regulate protein expression and to achieve optimal protein structure and function.
authors: Department of Physiology, The University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390, USA.
authors: Mian
authors: M
authors: Zhou
authors: Jinhu
authors: J
authors: Guo
authors: Joonseok
authors: J
authors: Cha
authors: Michael
authors: M
authors: Chae
authors: She
authors: S
authors: Chen
authors: Jose M
authors: JM
authors: Barral
authors: Matthew S
authors: MS
authors: Sachs
authors: Yi
authors: Y
authors: Liu
mesh_terms: D056926:CLOCK Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D057906:Circadian Clocks / Q000235:genetics / Q000502:physiology; D002940:Circadian Rhythm / Q000235:genetics / Q000502:physiology; D003062:Codon / Q000235:genetics*; D025461:Feedback, Physiological; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D009492:Neurospora crassa / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016366:Open Reading Frames; D010766:Phosphorylation; D011487:Protein Conformation; D055550:Protein Stability; D014357:Trypsin / Q000378:metabolism
chemical_list: D003062:Codon; C087405:FRQ protein, Neurospora crassa; D005656:Fungal Proteins; D056926:CLOCK Proteins; D014357:Trypsin