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

Abstract

A mutant(‘lab strain’) of the hyperthermophilicarchaeonPyrococcusfuriosusDSM3638 exhibited an extended exponential phase andatypical cell aggregation behavior. Genomic DNA from the mutant culturewas sequenced and compared to wild-type (WT) DSM3638, revealing145genes with one or more insertions, deletions, or substitutions (12 silent, 33amino acid substitutions, and 100 frame-shifts). Approximately half of the mutated genes weretransposases or hypothetical proteins.The WT transcriptomerevealednumerous changes in amino acid and pyrimidine biosynthesis pathways coincidental with growth phase transitions, unlike the mutant whose transcriptome reflected the observedprolonged exponential phase. Targeted gene deletions,based on frame-shifted ORFs in the mutant genome, in a genetically tractable strain of P. furiosus (COM1) could not generate the extended exponential phase behavior observed for the mutant. For example, a putative radical SAM family protein (PF2064) was the most highly up-regulated ORF (>25-fold) in the WT between exponential and stationary phase, although this ORF was unresponsive in the mutant; deletion of this gene in P. furiosus COM1 resulted in no apparent phenotype. On the other hand, frame-shifting mutations in the mutantgenome negatively impacted transcription ofa flagellar biosynthesis operon (PF0329-PF0338).Consequently, cells in the mutant culture lacked flagella and, unlike the WT, showed minimal evidence of exopolysaccharide-based cell aggregation in post-exponential phase. Electron microscopyofPF0331-PF0337 deletionsin P. furiosus COM1 showed that absence of flagella impacted normal cell aggregation behavior and, furthermore,indicatedthat flagella play a key role, beyond motility, in thegrowthphysiology ofP. furiosus.

Next Generation DNA-Seq and Differential RNA-Seq Allow Re-annotation of the Pyrococcus furiosus DSM 3638 Genome and Provide Insights Into Archaeal Antisense Transcription

“…A similar observation concerning the occurrence of a lab strain was made in Michael Adams group (University of Georgia, Athens, Georgia). This lab strain exhibits an extended exponential growth phase and atypical cell aggregation behavior (Lewis et al, 2015). The genome sequence of the mutant showed 145 genes with one or more insertions, deletions or substitutions.…”

A LuxR‐type regulator, AcrR, regulates flagellar assembly and contributes to virulence, motility, biofilm formation, and growth ability of Acidovorax citrulli

“…The lack of flagella could lead to enhanced growth ability in prokaryotes. Pyrococcus furiosus DSM363 exhibited an enhanced growth ability when its flagella were absent (Lewis et al , ). The transcription regulator SwrA stimulates the transcription of the genes for σ D , which controls when Bacillus subtilis cells enter into the motile state with expression of flagellum biosynthesis genes from a state of growth as long and nonmotile chains (Kearns and Losick, ).…”

Rv3737 is required for Mycobacterium tuberculosis growth in vitro and in vivo and correlates with bacterial load and disease severity in human tuberculosis

“…Colonies were picked, and PCR and qPCR were used to confirm the presence of the hygromycin-gene flanking region and the absence of the Rv3737 gene (Fig. 1 B, C) [ 10 , 11 ].…”