Streptomyces telomeres contain a promoter.
Bidirectional replication of the linear chromosomes and plasmids of Streptomyces spp. results in single-strand overhangs at their 3' ends, which contain extensive complex palindromic sequences. The overhangs are believed to be patched by DNA synthesis primed by a terminal protein that remains covalently bound to the 5' ends of the telomeres. We discovered that in vitro a conserved 167-bp telomere DNA binds strongly to RNA polymerase holoenzyme and exhibits promoter activities stronger than those of an rRNA operon. In vivo, the telomere DNA exhibited promoter activity in both orientations on a circular plasmid in Streptomyces. The telomere promoter is also active on a linear plasmid during exponential growth. Such promoter activity in a telomere has not hitherto been observed in eukaryotic or prokaryotic replicons. Streptomyces telomere promoters may be involved in priming the terminal Okazaki fragment (during replication) replicative transfer (during conjugation), or expression of downstream genes (including a conserved ttrA helicase-like gene involved in conjugal transfer). Interestingly, the Streptomyces telomeres also function as a promoter in Escherichia coli and as a transcription enhancer in yeast.
Lin
Yuh-ru
YR
Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Shih-Pai, Taipei 112, Taiwan.
Hahn
Mi-Young
MY
Roe
Jung-Hye
JH
Huang
Tzu-Wen
TW
Tsai
Hsiu-Hui
HH
Lin
Yung-Feng
YF
Su
Tsung-Sheng
TS
Chan
Yu-Jiun
YJ
Chen
Carton W
CW
D002460:Cell Line; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D006801:Humans; D008957:Models, Genetic; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011485:Protein Binding; D013302:Streptomyces / Q000235:genetics*; D016615:Telomere / Q000235:genetics*
D012321:DNA-Directed RNA Polymerases