Project description:In this study, we identified the O-glycosylation sites in recombinant Clostridium botulinum flagellin (CbFla) and Geobacillus kaustophilus flagellins, GkFlaA1 and GkFlaA2, expressed from the E. coli strains, EV136 and EV240 (K1:K12 strains engineered by Prof. Eric Vimr’s group to accumulate CMP-sialic acid in the cytosol), EV36 (wildtype K1:K12 strain), and BL21(DE3) (laboratory strain used for protein expression using T7 RNA polymerase). The recombinant flagellins were expressed with or without co-expression of motility associated factor (Maf) (flagellin nonulosonic acid glycosyltransferase) in these strains, purified and subjected to MS/MS analysis at Taplin Biological Mass Spectrometry facility.
Project description:We present herein the first complete genome sequence of a thermophilic Bacillus-related species, Geobacillus kaustophilus HTA426, which is composed of a 3.54 Mb chromosome and a 47.9 kb plasmid, along with a comparative analysis with five other mesophilic bacillar genomes. Upon orthologous grouping of the six bacillar sequenced genomes, it was found that 1257 common orthologous groups composed of 1308 genes (37%) are shared by all the bacilli, whereas 839 genes (24%) in the G.kaustophilus genome were found to be unique to that species. We were able to find the first prokaryotic sperm protamine P1 homolog, polyamine synthase, polyamine ABC transporter and RNA methylase in the 839 unique genes; these may contribute to thermophily by stabilizing the nucleic acids. Contrasting results were obtained from the principal component analysis (PCA) of the amino acid composition and synonymous codon usage for highlighting the thermophilic signature of the G.kaustophilus genome. Only in the PCA of the amino acid composition were the Bacillus-related species located near, but were distinguishable from, the borderline distinguishing thermophiles from mesophiles on the second principal axis. Further analysis revealed some asymmetric amino acid substitutions between the thermophiles and the mesophiles, which are possibly associated with the thermoadaptation of the organism.
Project description:Thermophiles have important advantages over mesophiles as host organisms for high-temperature bioprocesses, functional production of thermostable enzymes, and efficient expression of enzymatic activities in vivo. To capitalize on these advantages of thermophiles, we describe here a new inducible gene expression system in the thermophile Geobacillus kaustophilus HTA426. Six promoter regions in the HTA426 genome were identified and analyzed for expression profiles using ?-galactosidase reporter assay. This analysis identified a promoter region upstream of a putative amylose-metabolizing gene cluster that directed high-level expression of the reporter gene. The expression was >280-fold that without a promoter and was further enhanced 12-fold by maltose addition. In association with a multicopy plasmid, this promoter region was used to express heterologous genes. Several genes, including a gene whose product was insoluble when expressed in Escherichia coli, were successfully expressed as soluble proteins, with yields of 0.16 to 59 mg/liter, and conferred new functions to G. kaustophilus strains. Remarkably, cellulase and ?-amylase genes conferred the ability to degrade cellulose paper and insoluble starch at high temperatures, respectively, generating thermophiles with the potential to degrade plant biomass. Our results demonstrate that this novel expression system expands the potential applications of G. kaustophilus.
Project description:Counterselection systems facilitate marker-free genetic modifications in microbes by enabling positive selections for both the introduction of a marker gene into the microbe and elimination of the marker from the microbe. Here we report a counterselection system for Geobacillus kaustophilus HTA426, established through simultaneous disruption of the pyrF and pyrR genes. The pyrF gene, essential for pyrimidine biosynthesis and metabolization of 5-fluoroorotic acid (5-FOA) to toxic metabolites, was disrupted by homologous recombination. The resultant MK54 strain (?pyrF) was auxotrophic for uracil and resistant to 5-FOA. MK54 complemented with pyrF was prototrophic for uracil but insensitive to 5-FOA in the presence of uracil. To confer 5-FOA sensitivity, the pyrR gene encoding an attenuator to repress pyrimidine biosynthesis by sensing uracil derivatives was disrupted. The resultant MK72 strain (?pyrF ?pyrR) was auxotrophic for uracil and resistant to 5-FOA. MK72 complemented with pyrF was prototrophic for uracil and 5-FOA sensitive even in the presence of uracil. The results suggested that pyrF could serve as a counterselection marker in MK72, which was demonstrated by efficient marker-free integrations of heterologous ?-galactosidase and ?-amylase genes. The integrated genes were functionally expressed in G. kaustophilus and conferred new functions on the thermophile. This report describes the first establishment of a pyrF-based counterselection system in a Bacillus-related bacterium, along with the first demonstration of homologous recombination and heterologous gene expression in G. kaustophilus. Our results also suggest a new strategy for establishment of counterselection systems.