J Mol Biol 1969,44(1):209–214.CrossRefPubMed 35. Magnuson K, Carey MR, Cronan JE Jr: The putative fabJ gene of Escherichia coli fatty acid synthesis is the fabF gene. J Bacteriol 1995,177(12):3593–3595.PubMed Authors’ contributions LZ cloned Clostridium acetobutylicium fabFs genes, constructed several fabF expression vectors and did complementation experiments with fabFs expression vectors. JC cloned Clostridium acetobutylicium fabZ LY2603618 cell line gene and

made E. coli fabZ mutant. BL changed codons that correspond to rare E. coli tRNA species in C. acetobutylicium fabZ to codons favored in E. coli by site-directed mutagenesis. SF carried out biochemical studies on FabF and FabZ of C. acetobutylicium in vitro. JL performed expression experiments and purified FabF and FabZ proteins. SW helped to design the PCR primers. JEC participated in the design of the study and helped to draft the manuscript. HW conceived of the study, and participated in its design and coordination and helped to draft the manuscript. All authors read and approved the final manuscript.”
“Background Adaptation is important for survival of bacteria in various natural environments, but the underlying mechanisms are not fully understood.

Bacteria are often present in large communities (e.g., biofilm [1]) in nature, and adaptation can occur at population levels. An important adaptive MK-0457 supplier strategy is the generation of variants to maximize bacteria fitness at the population level DCLK1 in response to fluctuating environments [2, 3]. These variants may result from LY2874455 spontaneous mutations selected within a population or from non-genetic changes. For example, to evade host immune system, some pathogens can alter surface antigen structure [4], termed phase variation [4, 5], through revertible high frequency mutation of genes encoding

surface proteins [2, 5]. Bacteria also exhibit cell-to-cell variation in gene expression, termed individuality [2], even in an isogenic population. For example, under suboptimal induction conditions, the lac operon in Escherichia coli exhibits two distinct expression states, either fully induced or non-induced, but not an intermediate [6]. Gene expression noise due to stochastic events also results in phenotypic variation within isogenic E. coli populations [2, 7]. Both genetic selection and individuality are likely important for bacterial adaptation in natural environments [2]. An important adaptation regulator is the alternative sigma factor RpoS widely found in E. coli and many other proteobacteria [8, 9]. RpoS controls a large regulon [10–14] and plays a critical role in survival against stresses, such as prolonged starvation [15], low pH [16], thermal stress [17], near-UV exposure [18] and oxidative stress [18]. Despite the importance of RpoS, many attenuating mutations in the rpoS gene have been identified in both laboratory and natural E. coli strains.