To find the primase recognition site at the telomere of Streptomyces

• Main Authors: Huei-ying Lin, 林蕙盈
• Other Authors: 黃志宏
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/ew65cr

碩士 === 國立臺北科技大學 === 生物科技研究所 === 100 === Streptomyces chromosomes and some of plasmids are linear, the linear replicon initiate replication from the middle to both sides. When the lagging strand to the last Okazaki fragment and the primer was removed, it will leave a 3’ strands overhang at end. Rich palindromes synthesis proceeded in this single-strand make this sequence form a stable secondary structure that could be identified by Tap with TP protein is then working as primer and single-strand gap as a template to complete the end of the replication via DNA polymerase. Previous studies, showed that the linear plasmids carried the telomeres of S. rochei pSLA2, S. coelicolor and SLP2 generate single-stranded gaps about 280 nt, 320 and 250 nt in length, respectively. Huang I-Huei’s studies, using polymerase chain reaction, found that for linear plasmid replication with S. lividans telomeres, the single-stranded gap is about 300 nt long. We set lead a hypothesis based on all the previous research results that those gap structures should be caused by a specific DNA sequence recognized by primase of the last Okazaki fragment. In our study we focus on identifying the primase recognition site of Streptomyces linear replicons. In this study, we used the linear plasmids with different telomeres from S. liviidans, S. coelicolor and SLP2. We found that when DNA telomeres were too short, the replication intermediates couldn’t be observed. It suggested that to the length of single strand part could be too short to be isolated. But the previous studies did showed the possible location. We mutated the sequence, to see how it affects the length of the single strand gap to get the exact location of the primase recognition site and results suggested that the linear plasmid with the telomeres of S. lividans has its primase recognition site located approximately 275 to 285 nt from the end.