Disease relevance of spoT

• The spoU gene of Escherichia coli, the fourth gene of the spoT operon, is essential for tRNA (Gm18) 2'-O-methyltransferase activity [1].
• Expression of spoT in Borrelia burgdorferi during serum starvation [2].
• A 2.2kb relA/spoT homologue was isolated from Mycobacterium tuberculosis (Mtb) genomic DNA by PCR-amplification [3].
• The relA and spoT genes were cloned from Neisseria gonorrhoeae strain MS11 and various insertional and deletion mutants were constructed [4].

High impact information on spoT

• Sequencing of several genes controlling the effectors of these regulons found a nonsynonymous mutation in spoT in one population [5].
• We have recently discovered homologues of bacterial relA/spoT genes in the model plant Nicotiana tabacum [6].
• Residual guanosine 3',5'-bispyrophosphate synthetic activity of relA null mutants can be eliminated by spoT null mutations [7].
• Here, the effects of spoT gene insertions and deletions are compared with analogous alterations in neighboring genes in the spo operon and found to be lethal in relA+ strains as well as slower growing in relAl backgrounds than delta relA hosts [7].
• Cells with null alleles in both the relA and spoT genes are found no longer to accumulate ppGpp after glucose exhaustion or after chelation of manganese ions by picolinic acid addition; the inability to form ppGpp is reversed by a minimal spoT gene on a multicopy plasmid [7].

Chemical compound and disease context of spoT

• An Escherichia coli K12 delta relA delta spoT mutant lacking the ability to synthesize ppGpp lost viability at an increased rate during both glucose and seryl-tRNA starvation [8].
• The Escherichia coli spoT gene encodes a guanosine-3',5'-bispyrophosphate (ppGpp) 3'-pyrophosphohydrolase known to be responsible for cellular (ppGpp) degradation [9].
• This genetic organization is similar to that in Streptomyces coelicolor A3(2) and Streptococcus equismilis H46A. relA shows significant similarity to the Escherichia coli relA and spoT genes, which are responsible for the synthesis and degradation of the highly phosphorylated guanosine nucleotides (p)ppGpp, triggering the stringent response [10].
• Starving of Escherichia coli cells for inorganic orthophosphate (Pi) results in the accumulation of spoT-dependent ppGpp and induces the expression of genes of the PHO regulon [11].
• The global transcriptional regulator (p)ppGpp (guanosine-3'-diphosphate-5'-triphosphate and guanosine-3',5'-bisphosphate, collectively) produced by the relA and spoT genes in Escherichia coli allows bacteria to adapt to different environmental stresses [12].

Biological context of spoT

• We have localized the Escherichia coli K12 gltS gene with respect to the spoT gene, sequenced it, and recombined a null insertion-deletion allele into the chromosome without loss of viability [13].
• Two spoT mutations (spoT202 and spoT203) have been localized to an open reading frame by complementation of function as well as by genetic marker rescue [9].
• The DNA sequence of the spoT region is presented [9].
• The genome of Borrelia burgdorferi encodes a single chromosomal rel gene (BB0198) (B. burgdorferi rel [rel(Bbu)]) homologous to relA and spoT of E. coli [12].
• Interestingly, sequence data together with an altered phenotype with respect to the accumulation of guanosine 3',5'-bispyrophosphate (ppGpp) imply that one of the genes (csrS) identified by this approach is an Escherichia coli spoT equivalent [14].

Other interactions of spoT

• The delta relA delta spoT mutant maintained high expression of several ribosomal proteins during starvation and appeared to exhibit significantly decreased translational fidelity, as demonstrated by an unusual heterogeneity in the isoelectric point of several proteins and the failure to express higher molecular weight proteins during starvation [8].
• The rpoZ gene for the omega subunit of Escherichia coli RNA polymerase constitutes single operon with the spoT gene, which is responsible for the maintenance of stringent response under nutrient starvation conditions [15].

Analytical, diagnostic and therapeutic context of spoT

• A 2.9-kb fragment containing a putative spoT gene was isolated from B. burgdorferi genomic DNA by PCR amplification and cloned into a pBAD24 vector [2].
• Northern blot analysis suggests that spoT transcript was approximately 900 nucleotides in length [2].
• Reverse transcriptase PCR (RT-PCR) was used to detect spoT mRNA from approximately 10(6) cells starved for serum in RPMI for 2.5 to 30 min or incubated in tick saliva for 15 min [2].

References