The Rate and Character of Spontaneous Mutation in Thermus thermophilus

Abstract

Selection of spontaneous, loss-of-function mutations at two chromosomal loci (pyrF and pyrE) enabled the first molecular-level analysis of replication fidelity in the extremely thermophilic bacterium Thermus thermophilus. Two different methods yielded similar mutation rates, and mutational spectra determined by sequencing of independent mutants revealed a variety of replication errors distributed throughout the target genes. The genomic mutation rate estimated from these targets, 0.00097 6 0.00052 per replication, was lower than corresponding estimates from mesophilic microorganisms, primarily because of a low rate of base substitution. However, both the rate and spectrum of spontaneous mutations in T. thermophilus resembled those of the thermoacidophilic archaeon Sulfolobus acidocaldarius, despite important molecular differences between these two thermophiles and their genomes.

Proteome Analyses of Hydrogen-producing Hyperthermophilic Archaeon Thermococcus onnurineus NA1 in Different One-carbon Substrate Culture Conditions

“…Thus, the addition of formate at a high temperature may lead to the inhibition of DNA synthesis by damaging the DNA molecule. However, the spontaneous mutation rates of thermophilic archaea are reported to be lower than those of other mesophilic bacteria, despite the higher chemical instability of their DNA (36,37). Therefore, hyperthermophiles, including T. onnurineus NA1, seem to possess molecular strategies for DNA repair, to compensate for the intrinsic instability of DNA at their preferred growth temperatures and under acidic conditions (36,38).…”

The apt /6-Methylpurine Counterselection System and Its Applications in Genetic Studies of the Hyperthermophilic Archaeon Sulfolobus islandicus

“…Another reporter gene that has been used in the forward mutation assay is the pyrEF/5-FOA system, with which mutation profiles have been obtained for S. acidocaldarius, S. solfataricus, and S. islandicus (50,51). The profile of frameshifts, tandem duplications, and larger deletion and BPSs obtained in this work was generated from molecular analysis of the apt locus from over 200 6-MP r strains.…”

A mutant (‘lab strain’) of the hyperthermophilic archaeon Pyrococcus furiosus, lacking flagella, has unusual growth physiology

“…Of particular interest have been the extreme thermophiles that, by virtue of the high temperature biotopes that they inhabit, could be especially vulnerable to DNA damage (DiRuggiero et al 1999; Drake 2009; Grogan 1998; Grogan et al 2001; Mackwan et al 2008; Majernik et al 2004; Makarova et al 2002; Martusewitsch et al 2000; Omelchenko et al 2005; Watrin and Prieur 1996; Williams et al 2007). The relative rate of mutations in extreme thermophiles compared to mesophiles is not known in any comprehensive sense.…”

“…For example, spontaneous mutation characteristics in target genes in Thermusthermophilus (a bacterium) and Sulfolobusacidocaldarius (an archaeon) were found to be comparable, despite the phylogenetic and physiological differences that exist between the two microorganisms (Mackwan et al 2008). Also, a chloramphenicol-resistant, mutant of the hyperthermophilic bacterium Thermotogamaritima containedseveral nucleotide changes in ribosomal genes, resulting in significant transcriptomic differences between the mutant and wild-type during growth in the presence and absence of the antibiotic (Montero et al 2007).…”