Authors: Aidan L Kerr Young Jae Jeon Charles J Svenson Peter L Rogers Brett A Neilan
Publish Date: 2010/10/19
Volume: 89, Issue: 3, Pages: 761-769
Abstract
To better understand the DNA restrictionmodification RM systems for more amenable strain development of the alternative industrial ethanologen Zymomonas mobilis three gene knockout mutants were constructed The gene knockout mutants were tested for their DNA restriction activities by the determination of transformation efficiency using methylated and unmethylated foreign plasmid DNAs Inactivation of a putative mrr gene encoded by ZMO0028 zmrr resulted in a 60fold increase in the transformation efficiency when unmethylated plasmid DNA was used This indicated that the putative mrr gene may serve as a type IV restrictionmodification system in Z mobilis ZM4 To assign the function of a putative type I DNA methyltransferase encoded by ZMO1933 putative S subunit and ZMO1934 putative M subunit the putative S subunit was inactivated The gene inactivation of ZMO1933 resulted in a 30fold increase in the transformation efficiency when methylated plasmid DNA was introduced indicating that the putative S subunit possibly serves as a part of functional type I RM systems Growth studies performed on the mutant strains indicate inactivation of the type I S subunit resulted in a lower maximum specific glucose consumption rate and biomass yield while inactivation of the type IV Zmrr had the opposite effect with an increase in the maximum specific growth rate and biomass yield
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