TITLE Functional redundancy of the duplex telomeric DNA-binding proteins in Arabidopsis
AUTHOR Chung-Mong CHEN
Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan 115, Republic of China
Chi-Ting WANG
Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan 115, Republic of China
Yu-Hsin KAO
Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan 115, Republic of China
Geen-Dong CHANG
Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan 106, Republic of China
Chia-Hsing HO
Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan 106, Republic of China
Feng-Ming LEE
Institute of Plant Biology, National Taiwan University, Taipei, Taiwan 106, Republic of China
Ming-Jhy HSEU
Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan 115, Republic of China
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ABSTRACT AtTRP1 is an Arabidopsis protein that binds duplex telomeric DNA in vitro. Here we showed that knockout of AtTRP1 did not change significantly the telomere length in plant. This implies that either AtTRP1 does not participate in the regulation of telomere length or the Arabidopsis genome contains other genes functionally redundant to AtTRP1. Sequence analysis of Arabidopsis genome together with molecular cloning enabled us to identify two additional genes AtTRP3 and AtTRP4 and the corresponding cDNA clones encoding AtTRP1-like proteins. The C-terminal regions of both AtTRP3 and AtTRP4 proteins bind specifically duplex telomeric DNA in vitro. The amino acid sequence of AtTRP4 is identical to that of another Arabidopsis protein TRFL1 except with an internal deletion of six amino acids, suggesting that AtTRP4 and TRFL1 may be derived from the same gene by alternative splicing. This speculation was further confirmed by DNA sequence analysis of RT-PCR products specific for AtTRP4 and TRFL1 transcripts. Our data together with reports from other researchers revealed that Arabidopsis contains at least seven different duplex telomeric DNA-binding proteins encoded by a six-member gene family, named AtTRP. We proposed that some members of the AtTRP family may be functionally redundant in the regulation of telomere length in Arabidopsis.
KEYWORD Alternative splicing; Arabidopsis thaliana; Functional redundancy; Knockout mutant; Telomere length; Telomeric DNA-binding protein;
ARTICLE INFO Botanical Bulletin of Academia Sinica, Volume 46 Number 4 October 2005, page 315-324, 10 pages
PUBLISHER Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan, Republic of China