Abstract
BackgroundAlthough several chloroplast RNA splicing and ribosome maturation (CRM) domain-containing proteins have been characterized for intron splicing and rRNA processing during chloroplast gene expression, the functional role of a majority of CRM domain proteins in plant growth and development as well as chloroplast RNA metabolism remains largely unknown. Here, we characterized the developmental and stress response roles of a nuclear-encoded chloroplast protein harboring a single CRM domain (At4g39040), designated CFM4, in Arabidopsis thaliana.ResultsAnalysis of CFM4-GFP fusion proteins revealed that CFM4 is localized to chloroplasts. The loss-of-function T-DNA insertion mutants for CFM4 (cfm4) displayed retarded growth and delayed senescence, suggesting that CFM4 plays a role in growth and development of plants under normal growth conditions. In addition, cfm4 mutants showed retarded seed germination and seedling growth under stress conditions. No alteration in the splicing patterns of intron-containing chloroplast genes was observed in the mutant plants, but the processing of 16S and 4.5S rRNAs was abnormal in the mutant plants. Importantly, CFM4 was determined to possess RNA chaperone activity.ConclusionsThese results suggest that the chloroplast-targeted CFM4, one of two Arabidopsis genes encoding a single CRM domain-containing protein, harbors RNA chaperone activity and plays a role in the Arabidopsis growth and stress response by affecting rRNA processing in chloroplasts.
Highlights
Several chloroplast RNA splicing and ribosome maturation (CRM) domain-containing proteins have been characterized for intron splicing and rRNA processing during chloroplast gene expression, the functional role of a majority of CRM domain proteins in plant growth and development as well as chloroplast RNA metabolism remains largely unknown
Structural features and characterization of CRM family member subfamily4 (CFM4) in Arabidopsis Sixteen predicted CRM domain family members occur in the Arabidopsis genome, and they are classified into four groups, such as CRS1 subfamily, CAF subfamily, subfamily 3, and subfamily 4
The results showed that CFM4 family proteins share 35-50% amino acid sequence homology among dicot and monocot plants and share > 70% amino acid sequence homology among monocot plants (Additional file 1), suggesting that the single CRM domain-containing proteins are functionally conserved in dicots and monocots
Summary
Several chloroplast RNA splicing and ribosome maturation (CRM) domain-containing proteins have been characterized for intron splicing and rRNA processing during chloroplast gene expression, the functional role of a majority of CRM domain proteins in plant growth and development as well as chloroplast RNA metabolism remains largely unknown. Chloroplasts possess approximately 100-150 genes in their own circular genome that encodes messenger RNAs, ribosome RNAs, and transfer RNAs. In addition to its own gene products, functional communication between chloroplasts and nucleus is required, and many nuclear-encoded proteins are targeted to chloroplasts and play fundamental roles in the regulation of chloroplast gene expression. CRM (chloroplast RNA splicing and ribosome maturation) domain-containing proteins were first found in archaea and bacteria. Based on their structural data and predicted domain structures, CRM domain proteins were suggested to have RNA-binding activity [12]. It has been demonstrated that mutation in CRM domain-containing protein genes results in pale-green phenotypes, delayed development, and aborted seed production in plants, indicating the important roles of CRM domain proteins in plant growth and development [11,12,17,20,21]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
