Chloroplasts evolved from an ancient cyanobacterial endosymbiont more than 1.5 billion years ago.During subsequent coevolution with the nuclear genome,the chloroplast genome has remained independent,albeit strongly re...Chloroplasts evolved from an ancient cyanobacterial endosymbiont more than 1.5 billion years ago.During subsequent coevolution with the nuclear genome,the chloroplast genome has remained independent,albeit strongly reduced,with its own transcriptional machinery and distinct features,such as chloroplast-specific innovations in gene expression and complicated post-transcriptional processing.Light activates the expression of chloroplast genes via mechanisms that optimize photosynthesis,minimize photodamage,and prioritize energy investments.Over the past few years,studies have moved from describing phases of chloroplast gene expression to exploring the underlying mechanisms.In this review,we focus on recent advances and emerging principles that govern chloroplast gene expression in land plants.We discuss engineering of pentatricopeptide repeat proteins and its biotechnological effects on chloroplast RNA research;new techniques for characterizing the molecular mechanisms of chloroplast gene expression;and important aspects of chloroplast gene expression for improving crop yield and stress tolerance.We also discuss biological and mechanistic questions that remain to be answered in the future.展开更多
Besides transcription regulation, gene expression is also regulated at translation level. Although translation regulation is mainly mediated by translation initiation, an abundance of evi-dence shows that the terminat...Besides transcription regulation, gene expression is also regulated at translation level. Although translation regulation is mainly mediated by translation initiation, an abundance of evi-dence shows that the termination phase of translation is also important for gene expression. The expression of lN gene is down regulated at translation level in L24 mutant, however the precise mechanism still remains unknown. We report here that in an L24 mutant strain, the expression of lac-lN and GST-lN is decreased to 25% and 50% of that in wild type T83 strain respectively. Strikingly, the yield of GST-lN fusion protein in L24 mutant can be restored to the level as in T83 wild type strain by changing the two codons upstream lN stop codon. These findings imply that the stop codon and its context are involved in the translation regulation. The possible reason is that the translation termination complex containing L24 mutant ribosome may not dissociate prop-erly in stop code region. This failure of disengagement from mRNA will slow down the process of following ribosomes, and consequently decrease the efficiency of lN gene expression.展开更多
Ⅰ. INTRODUCTIONAll protein syntheses are carried out on ribosomes, therefore the ribosomes are extremely important to biological activities. So far the composition of the ribosomal structure including three kinds of ...Ⅰ. INTRODUCTIONAll protein syntheses are carried out on ribosomes, therefore the ribosomes are extremely important to biological activities. So far the composition of the ribosomal structure including three kinds of rRNAs and over filly ribosomal proteins has been elucidated in detail. But the exact functions of the ribosomal proteins remain almost totally unknown.展开更多
基金supported by the National Key Research and Development Program of China(grant no.2020YFA0907600)the National Natural Science Foundation of China(grant nos.31730102 and 32000184)+1 种基金the Natural Science Foundation of Shandong Province(grant no.ZR2020QC023)the China Postdoctoral Science Foundation(grant no.2020M672093).
文摘Chloroplasts evolved from an ancient cyanobacterial endosymbiont more than 1.5 billion years ago.During subsequent coevolution with the nuclear genome,the chloroplast genome has remained independent,albeit strongly reduced,with its own transcriptional machinery and distinct features,such as chloroplast-specific innovations in gene expression and complicated post-transcriptional processing.Light activates the expression of chloroplast genes via mechanisms that optimize photosynthesis,minimize photodamage,and prioritize energy investments.Over the past few years,studies have moved from describing phases of chloroplast gene expression to exploring the underlying mechanisms.In this review,we focus on recent advances and emerging principles that govern chloroplast gene expression in land plants.We discuss engineering of pentatricopeptide repeat proteins and its biotechnological effects on chloroplast RNA research;new techniques for characterizing the molecular mechanisms of chloroplast gene expression;and important aspects of chloroplast gene expression for improving crop yield and stress tolerance.We also discuss biological and mechanistic questions that remain to be answered in the future.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 39870407). References
文摘Besides transcription regulation, gene expression is also regulated at translation level. Although translation regulation is mainly mediated by translation initiation, an abundance of evi-dence shows that the termination phase of translation is also important for gene expression. The expression of lN gene is down regulated at translation level in L24 mutant, however the precise mechanism still remains unknown. We report here that in an L24 mutant strain, the expression of lac-lN and GST-lN is decreased to 25% and 50% of that in wild type T83 strain respectively. Strikingly, the yield of GST-lN fusion protein in L24 mutant can be restored to the level as in T83 wild type strain by changing the two codons upstream lN stop codon. These findings imply that the stop codon and its context are involved in the translation regulation. The possible reason is that the translation termination complex containing L24 mutant ribosome may not dissociate prop-erly in stop code region. This failure of disengagement from mRNA will slow down the process of following ribosomes, and consequently decrease the efficiency of lN gene expression.
基金Project supported by the National Natural Science Foundation of China.
文摘Ⅰ. INTRODUCTIONAll protein syntheses are carried out on ribosomes, therefore the ribosomes are extremely important to biological activities. So far the composition of the ribosomal structure including three kinds of rRNAs and over filly ribosomal proteins has been elucidated in detail. But the exact functions of the ribosomal proteins remain almost totally unknown.
