Disease relevance of pncA

• In this study the nucleotide sequence of the pncA gene from 59 Mycobacterium tuberculosis clinical isolates was analyzed [1].
• Escherichia coli isolates expressing individually five of the eight katG mutations showed loss of catalase and INH oxidation activities, and isolates carrying any of the five pncA mutations showed no pyrazinamidase activity, indicating that these mutations are associated with INH and PZA resistance, respectively [2].
• The remaining four child cases, as well as all adult cases with detectable IS6110, showed no motility shift in pncA PCR-SSCP and had the same one-band pattern as M. tuberculosis in oxyR PCR-RFLP, suggesting TB lymphadenitis [3].
• For comparison, 37 adult cases of tuberculous lymphadenitis were also analysed by PCR-single strand conformation polymorphism (SSCP) assay for pncA and by PCR-RFLP for oxyR [3].

High impact information on pncA

• Mutations in pncA, a gene encoding pyrazinamidase/nicotinamidase, cause resistance to the antituberculous drug pyrazinamide in tubercle bacillus [4].
• PCR, together with direct DNA sequencing and PCR-restriction fragment length polymorphism (RFLP) assay, was then performed to identify polymorphic nucleotide in pncA and oxyR, respectively [3].
• The purpose of this study was to investigate the feasibility of differentiating BCG-LA from TB in lymph nodes (LNs) by molecular analyses of two recently identified genes, pncA and oxyR [3].
• Differentiation of BCG-induced lymphadenitis from tuberculosis in lymph node biopsy specimens by molecular analyses of pncA and oxyR [3].
• A region of pncA was observed with a high GC content and a melting temperature approaching 90 degrees C that was initially refractory to denaturation, and a DGGE target fragment was specifically designed to detect mutations in this region [5].

Chemical compound and disease context of pncA

• Characterization of pncA mutations in pyrazinamide-resistant Mycobacterium tuberculosis in Brazil [1].
• PZA is a prodrug that has to be converted to the active form pyrazinoic acid by pyrazinamidase (PZase) activity, encoded by the pncA gene of Mycobacterium tuberculosis, and loss of PZase activity is associated with PZA resistance [6].

Biological context of pncA

• The rpoB and pncA mutations seen in the Turkish isolates defined six distinct genotypes amongst the six MDR isolates, while standard IS6110 typing discriminated only four [7].
• In striking contrast, 72% of the 67 resistant organisms had pncA mutations that altered the primary amino acid sequence of pyrazinamidase [8].
• Interestingly, 20 PZA-monoresistant strains and 1 multidrug-resistant isolate from Quebec, Canada, all had the same pncA mutation profile, consisting of an 8-nucleotide deletion and an amino acid substitution of Arg140-->Ser [6].
• We examined the correlation of mutations in the pyrazinamidase (PZase) gene (pncA) with the pyrazinamide (PZA) resistance phenotype with 60 Mycobacterium tuberculosis isolates [9].
• In this study, we report the development of a rapid PCR-single-strand conformation polymorphism (SSCP) assay to differentiate M. bovis from M. tuberculosis strains, based on the detection of a single characteristic point mutation in the PZase gene (pncA) of M. bovis [10].

Anatomical context of pncA

• Rapid genotyping was performed on the sputum from a patient who presented 2 years after the initial MDR-TB outbreak and this showed rpoB and pncA genotypes identical to the other outbreak isolates [7].

Associations of pncA with chemical compounds

• Mutations in the pncA gene were identified in 29 of 40 pyrazinamide-resistant isolates, and no pyrazinamidase activity was detected in 39 of them [1].
• The PZase activity was measured by pyrazinamide deamination to pyrazinoic acid and ammonia, and the entire pncA sequence including the 410 bp upstream from the start codon was determined by DNA sequencing of purified PCR products [11].
• The pzaA-complemented strain was hypersensitive to PZA (MIC, </=10 microg/ml) and nicotinamide (MIC, >/=20 microg/ml) and was also sensitive to benzamide (MIC, 20 microg/ml), unlike the wild-type and pncA-complemented mutant strains, which were highly resistant to this amide (MIC, >500 microg/ml) [12].
• Isolates reported by local laboratories to be PZA monoresistant were sent to the state reference laboratory for repeat susceptibility testing using the BACTEC radiometric method and to the Centers for Disease Control and Prevention for pncA sequencing and PCR-restriction fragment length polymorphism (RFLP) analysis of the oxyR gene [13].
• The oligonucleotide primers were chosen from a 500-bp genomic fragment which is well conserved in M. bovis and the pncA gene (based on M. tuberculosis-specific nucleotide polymorphism, a cytosine residue at position 169), specific for M. tuberculosis [14].

Other interactions of pncA

• RMP and PZA resistances are associated with multiple mutations within the rpoB and pncA genes, respectively [15].
• Sequencing of the pncA gene revealed a polymorphism characteristic of M. tuberculosis, whereas oxyR, katG and gyrA sequences were characteristic of Mycobacterium bovis [16].
• Mutation screening was done by amplifying the pncA, gyrA, and gyrB genes by the polymerase chain reaction (PCR) and direct automated sequencing [17].

Analytical, diagnostic and therapeutic context of pncA

• Microarray analysis was performed in a blind manner on 33 clinical isolates of M. tuberculosis for which the sequence of the pncA gene had not previously been determined [18].
• Temperature-mediated heteroduplex analysis for detection of pncA mutations associated with pyrazinamide resistance and differentiation between Mycobacterium tuberculosis and Mycobacterium bovis by denaturing high- performance liquid chromatography [19].
• Sequence analysis shows different novel mutations within the pncA gene of these variants [20].
• DESIGN: The association of PZase activity, minimum inhibitory concentrations (MICs), and mutations in the pncA gene of M. tuberculosis isolated in mostly Asian countries was investigated [21].

References