Arabidopsis thaliana L. yellow variegated （var2） mutant is defective in a chloroplast FtsH family metalloprotease, AtFtsH2/VAR2, and displays an intriguing green and white leaf variegation. This unique var2-mediated...Arabidopsis thaliana L. yellow variegated （var2） mutant is defective in a chloroplast FtsH family metalloprotease, AtFtsH2/VAR2, and displays an intriguing green and white leaf variegation. This unique var2-mediated leaf variegation offers a simple yet powerful tool for dissecting the genetic regulation of chloroplast development. Here, we report the isolation and characterization of a new var2 suppressor gene, SUPPRESSOR OF VARIEGA TION8 （SVR8）, which encodes a putative chloroplast ribosomal large subunit protein, L24. Mutations in SVR8 suppress var2 leaf variegation at ambient temperature and partially suppress the cold-induced chlorosis phenotype of var2. Loss of SVR8 causes unique chloroplast rRNA processing defects, particularly the 23S-4.5S dicistronic precursor. The recovery of the major abnormal processing site in svr823S-4.5S precursor indicate that it does not lie in the same position where SVR8/L24 binds on the ribosome. Surprisingly, we found that the loss of a chloroplast ribosomal small subunit protein, $21, results in aberrant chloroplast rRNA processing but not suppression of var2 variegation. These findings suggest that the disruption of specific aspects of chloroplast translation, rather than a general impairment in chloroplast translation, suppress var2variegation and the existence of complex genetic interactions in chloroplast development.展开更多
Objectives To identify possible mutations in our previously cloned candidate gene for hereditary multiple exostoses type Ⅱ (EXT2) in affected members of EXT families so as to confirm that it is the disease causing ...Objectives To identify possible mutations in our previously cloned candidate gene for hereditary multiple exostoses type Ⅱ (EXT2) in affected members of EXT families so as to confirm that it is the disease causing gene. Methods The mutation was detected first by single strand conformational polymorphism(SSCP) of all coding exons of the candidate gene and then by sequencing analysis. Results After analyzing 37 patients from 20 Chinese EXT families by SSCP and DNA sequencing analysis, one 2 bp insertion mutation was identified in this candidate gene in affected members of an EXT family. This mutation resulted in the frameshift and generated a truncated gene product consisting of 105 amino acids. Conclusions The identification of the mutation in the candidate gene indicates that this novel gene is responsible for EXT2 (one of the disease causing gene of EXT).展开更多
基金supported by funds from National Natural Science Foundation of China to F.Y. (31071073 31170219) and to X.L. (31100864)+2 种基金by Chinese Ministry of Education Program of New Century Excellent Talents in University (NCET 09 0657) to F.Yby funding to S.R. from the US Department of Energy Energy Biosciences panel (DE FG02 94ER20147)
文摘Arabidopsis thaliana L. yellow variegated （var2） mutant is defective in a chloroplast FtsH family metalloprotease, AtFtsH2/VAR2, and displays an intriguing green and white leaf variegation. This unique var2-mediated leaf variegation offers a simple yet powerful tool for dissecting the genetic regulation of chloroplast development. Here, we report the isolation and characterization of a new var2 suppressor gene, SUPPRESSOR OF VARIEGA TION8 （SVR8）, which encodes a putative chloroplast ribosomal large subunit protein, L24. Mutations in SVR8 suppress var2 leaf variegation at ambient temperature and partially suppress the cold-induced chlorosis phenotype of var2. Loss of SVR8 causes unique chloroplast rRNA processing defects, particularly the 23S-4.5S dicistronic precursor. The recovery of the major abnormal processing site in svr823S-4.5S precursor indicate that it does not lie in the same position where SVR8/L24 binds on the ribosome. Surprisingly, we found that the loss of a chloroplast ribosomal small subunit protein, $21, results in aberrant chloroplast rRNA processing but not suppression of var2 variegation. These findings suggest that the disruption of specific aspects of chloroplast translation, rather than a general impairment in chloroplast translation, suppress var2variegation and the existence of complex genetic interactions in chloroplast development.
文摘Objectives To identify possible mutations in our previously cloned candidate gene for hereditary multiple exostoses type Ⅱ (EXT2) in affected members of EXT families so as to confirm that it is the disease causing gene. Methods The mutation was detected first by single strand conformational polymorphism(SSCP) of all coding exons of the candidate gene and then by sequencing analysis. Results After analyzing 37 patients from 20 Chinese EXT families by SSCP and DNA sequencing analysis, one 2 bp insertion mutation was identified in this candidate gene in affected members of an EXT family. This mutation resulted in the frameshift and generated a truncated gene product consisting of 105 amino acids. Conclusions The identification of the mutation in the candidate gene indicates that this novel gene is responsible for EXT2 (one of the disease causing gene of EXT).
