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