Disease relevance of hktE

• To study the role of PGdx in virulence and to assess the requirement of H2O2-scavenging during the course of infection, both a pgdx single mutant and a pgdx/hktE double mutant of Hib were assayed for virulence in an infant rat model [1].
• However, Haemophilus influenzae type b strain Eagan (Hib), a causative agent of bacterial sepsis and meningitis in young children, disrupted in its hktE gene is not attenuated in virulence, and retains the ability to rapidly scavenge H2O2 [1].
• The sequence of the gene and the derived amino acid sequence showed that the gonococcal kat gene closely resembles the hktE gene of Haemophilus influenzae [2].
• When administered intranasally, the Eagan b+ hktE mutant produced wild-type levels of bacteremia and nasal colonization [3].
• The DNA sequence of this gene, called hktE, encodes a 508-amino-acid polypeptide with strong homology to eukaryotic catalases and E. coli katE [4].

High impact information on hktE

• These mutants show no detectable catalase production during exponential or stationary phases or following induction with hydrogen peroxide or ascorbic acid, indicating that hktE is the only functional hydroperoxidase gene present in these two strains of H. influenzae [3].
• Mutant H. influenzae lacking catalase and cultured in glutathione-deficient minimal medium is completely devoid of H2O2 scavenging activity and, accordingly, substantial amounts of H2O2 accumulate in the growth medium [5].
• We address here the role of glutathione in protection against hydrogen peroxide (H2O2) in Haemophilus influenzae and show that glutathione and catalase provide overlapping defense systems [5].
• Nucleotide sequence analysis of the catalase gene (designated katA) and flanking intergenic regions also revealed several occurrences of an 11-bp sequence that is closely related to the core DNA uptake signal sequence for natural transformation of Haemophilus influenzae [6].
• The catalase activity was localized in the periplasm of wild-type V. fischeri cells, where its role could be to detoxify hydrogen peroxide coming from the external environment [7].

Chemical compound and disease context of hktE

• Glutathione and catalase provide overlapping defenses for protection against respiration-generated hydrogen peroxide in Haemophilus influenzae [5].

Biological context of hktE

• The hktE gene maps to a 225-kb segment of the H. influenzae chromosome in a region encoding resistance to spectinomycin [4].
• Nineteen complementing clones with a catalase-positive phenotype were obtained and characterized after screening about 10(5) transformants [4].
• Five independent plasmid clones were isolated, all mapping to the same chromosomal region and encoding the H. pylori catalase [8].
• The sequenced Haemophilus influenzae Rd genome reveals one catalase, designated HktE, and no AhpR [1].

Anatomical context of hktE

• The cloning and genetic characterization of katA are essential steps for further investigation of the role of catalase in the defense of H. pylori against oxygen-dependent killing mechanisms by polymorphonuclear granulocytes, a process not well understood for this chronically persisting pathogen [8].

Associations of hktE with chemical compounds

• A. seminis was distinguished from the HH group by its lack of yellow pigment, production of catalase, growth in air, lack of a thiamine monophosphate requirement, and different cell envelope protein profile [9].

References