Disease relevance of hflB

• Cell growth and lambda phage development controlled by the same essential Escherichia coli gene, ftsH/hflB [1].
• The ftsH gene is essential for cell viability in Escherichia coli [2].
• The ftsH gene of Bacillus subtilis is involved in major cellular processes such as sporulation, stress adaptation and secretion [3].
• The ftsH gene of Caulobacter crescentus has been isolated and identified as a component of the general stress response of this organism [4].
• In contrast, the groEL gene, which is controlled in response to heat stress by both sigma32 and a HcrA/CIRCE mechanism, was not derepressed in an ftsH mutant [4].

High impact information on hflB

• The hflB gene is in the ftsJ-hflB operon, one promoter of which is positively regulated by heat shock and sigma 32 [5].
• Overproduction of SecY in the ftsH mutant cells proved to deleteriously affect cell growth and protein export, suggesting that elimination of uncomplexed SecY is important for optimum protein translocation and for the integrity of the membrane [6].
• Disruption of the chromosomal ftsH in combination with a lac promoter-controlled copy of ftsH on a plasmid rendered the cell viability dependent on lac induction [7].
• To search for additional cellular factors involved in membrane protein quality control, we isolated multicopy suppressors that alleviated the growth defect of the ftsH/htpX dual disruption mutant [8].
• AcnB has recently been shown to initiate a regulatory cascade controlling flagella biosynthesis in Salmonella enterica by binding to the ftsH transcript and inhibiting the synthesis of the FtsH protease [9].

Chemical compound and disease context of hflB

• Escherichia coli tolZ mutants are tolerant to colicins E2, E3, D, Ia, and Ib (Tol-), can grow on glucose but not on succinate or other nonfermentable carbon sources (Nfc-), and show temperature-sensitive growth (Ts) [10].

Biological context of hflB

• The suppressor mutation, named sfhC21, that allows Escherichia coli ftsH null mutant cells to survive was found to be an allele of fabZ encoding R-3-hydroxyacyl-ACP dehydrase, involved in a key step of fatty acid biosynthesis, and appears to upregulate the dehydrase [11].
• We have recently identified RrmJ, the first encoded protein of the rrmJ-ftsH heat shock operon, as being the Um(2552) methyltransferase of 23S rRNA, and reported that rrmJ-deficient strains exhibit growth defects, reduced translation rates and reduced stability of 70S ribosomes [12].
• Using this new phenotype caused by ftsH mutations, we also isolated a new temperature-sensitive ftsH mutant [13].
• Defective plasmid partition in ftsH mutants of Escherichia coli [13].
• Although ftsH is necessary for adaptation to heat, it is not involved in the regulation of the heat-shock response [3].

Anatomical context of hflB

• However, production of the mother cell sigma factors, sigmaE and sigmaK, was abnormal in the suppressed strains, and mutations in either spoVM or ftsH alone impaired sigma factor production and sporulation gene expression [14].
• The red algal chloroplast genome encodes an essential prokaryotic cell division gene, ftsH, which has never been found in the mitochondrial genome of any organism [15].

Associations of hflB with chemical compounds

• Mutations in ftsH cause an increase in the lipopolysaccharide/ phospholipid ratio due to stabilization of the lpxC gene product, which is involved in lipopolysaccharide synthesis and is a substrate for proteolysis by the FtsH protease [13].
• A search for genes involved in fermentation indicated that ftsH is required, and is also needed to a lesser extent for nitrate respiration [16].
• Glucose 6-phosphate uptake at pH 5.5, which is driven by a transmembrane pH gradient, in the tolZ mutant was similar to the parent level [17].
• In contrast, the uptake of methionine and alpha-methyl-D-glucoside, which is not dependent on delta-mu H+ and delta psi, was normal in the tolZ mutant [17].
• The tolZ mutant had a defect in the uptake of proline, glutamine, thiomethyl-beta-D-galactoside, and triphenylmethylphosphonium ion; these uptake systems are driven by an electrochemical proton gradient (delta-mu H+) or a membrane potential (delta psi) [17].

Other interactions of hflB

• We also identified another gene (ftsJ) affecting cell division in the region upstream of the ftsH gene [18].
• Escherichia coli mutant Y16 is a double mutant carrying thermosensitive ftsH and ftsI mutations [19].
• The ftsH gene of Mycobacterium smegmatis SN2 (MsftsH) was cloned from two independent partial genomic DNA libraries and characterized, along with the identification of ephA and folE as the neighbouring upstream and downstream genes respectively [20].
• Heat shock regulation in the ftsH null mutant of Escherichia coli: dissection of stability and activity control mechanisms of sigma32 in vivo [21].

Analytical, diagnostic and therapeutic context of hflB

• Nevertheless, reverse transcription-PCR and immunoblotting demonstrated for the first time that chloroplast-encoded ftsH is transcriptionally and translationally active [15].
• Complementation tests suggested that the ftsD220 mutation is not homologous to a Escherichia coli ftsH mutation [22].
• Southern hybridisation of the NheI digest of the cosmid SCY6F7 containing part of the genomic DNA of M. tuberculosis H37Rv using the PCR fragment as the probe identified the full-length ftsH gene in the 7.2-kb fragment [23].

References