title: Error-prone DnaE2 Balances the Genome Mutation Rates inMyxococcus xanthusDK1622.
abstract: dnaEis an alpha subunit of the tripartite protein complex of DNA polymerase III that is responsible for the replication of bacterial genome. ThednaEgene is often duplicated in many bacteria, and the duplicateddnaEgene was reported dispensable for cell survivals and error-prone in DNA replication in a mystery. In this study, we found that all sequenced myxobacterial genomes possessed twodnaEgenes. The duplicatednaEgenes were both highly conserved but evolved divergently, suggesting their importance in myxobacteria. UsingMyxococcus xanthusDK1622 as a model, we confirmed thatdnaE1 (MXAN_5844) was essential for cell survival, whilednaE2 (MXAN_3982) was dispensable and encoded an error-prone enzyme for replication. The deletion ofdnaE2 had small effects on cellular growth and social motility, but significantly decreased the development and sporulation abilities, which could be recovered by the complementation ofdnaE2. The expression ofdnaE1 was always greatly higher than that ofdnaE2 in either the growth or developmental stage. However, overexpression ofdnaE2 could not makednaE1 deletable, probably due to their protein structural and functional divergences. ThednaE2 overexpression not only improved the growth, development and sporulation abilities, but also raised the genome mutation rate ofM. xanthus. We argued that the low-expressed error-proneDnaE2 played as a balancer for the genome mutation rates, ensuring low mutation rates for cell adaptation in new environments but avoiding damages from high mutation rates to cells.
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University Jinan, China.
authors.forename: Ran
authors.initials: R
authors.lastname: Peng
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University Jinan, China.
authors.forename: Jiang-He
authors.initials: JH
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University Jinan, China.
authors.forename: Wan-Wan
authors.initials: WW
authors.lastname: Feng
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University Jinan, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University Jinan, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Yin
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University Jinan, China.
authors.forename: Ze-Shuo
authors.initials: ZS
authors.lastname: Li
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University Jinan, China.
authors.forename: Yue-Zhong
authors.initials: YZ
authors.lastname: Li
keywords: Myxococcus xanthus; chromosome replication; development and sporulation; dispensable; dnaE2 gene; error-prone; growth