DNA replication defects in a mutant deficient in the thioredoxin homolog YbbN

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• 作者：Hai-Tuong Le^a ; Valé ; rie Gautier^a ; Fatoum Kthiri^a ; Masamichi Kohiyama^a ; Tsutomu Katayama^b ; Gilbert Richarme^a ; ^{richarme@paris7.jussieu.fr}
• 关键词：Oxidoreductase ; Chaperone ; Thioredoxin ; β ; -cl DNA polymerase
• 刊名：Biochemical and Biophysical Research Communications
• 出版年：2011
• 出版时间：4 February 2011
• 年：2011
• 卷：405
• 期：1
• 页码：52-57
• 全文大小：442 K

文摘

Escherichia coli contains two thioredoxins, Trx1 and Trx2, and a thioredoxin-like protein, YbbN, that displays both redox and chaperone properties. Since three out of the six proteins of the YbbN interactome (Butland et al., 2005) are components of DNA polymerase 3 holoenzyme (i.e. the β-clamp DnaN, the θ subunit HolE and the δ′ subunit HolB), we investigated whether the ybbN mutant presents DNA replication defects. We found that this mutant incorporates ³H-thymidine at higher rates than the parental strain and displays overinitiation, hypermutator and filamentation phenotypes with the occurrence of anucleated cells. Moreover, YbbN functions as a bona fide chaperone in the refolding of the urea-unfolded β-clamp. These results suggest that the DNA replication and cell division defects of the ybbN mutant might best be explained by chaperone functions of YbbN in the biogenesis of DNA polymerase 3 holoenzyme.