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Gene Review

pbpX  -  penicillin-binding protein 2X

Streptococcus pneumoniae R6

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Disease relevance of pbpX


High impact information on pbpX


Chemical compound and disease context of pbpX


Biological context of pbpX

  • The phenotype of the 23.2x mutant remained stable after in vivo passage, which suggests that the pbpX gene is involved in growth, whereas virulent revertants of the 23.2b and 23.2b.2x mutants had no change in MIC [8].
  • Sequence analysis results of the pbp2b and pbpX alleles from these strains were in keeping with acquired penicillin resistance [8].
  • This study assessed the relationship between acquired resistance and virulence in single- and double-isogenic penicillin-resistant (Peni-R) mutants obtained by transformation of a virulent penicillin-susceptible recipient strain with pbp2b and pbpX polymerase chain reaction fragments from a Peni-R donor strain [8].
  • Mutation Q552E lowered the acylation efficiency for both penicillin G and cefotaxime when compared with S-PBP2x*. We propose that the introduction of a negative charge in strand beta3 conflicts with the negative charge of the beta-lactam [6].
  • The crystal structure of the penicillin-binding protein 2x from Streptococcus pneumoniae and its acyl-enzyme form: implication in drug resistance [9].

Associations of pbpX with chemical compounds

  • Fifty percent inhibitory concentrations for penicillin-binding protein 2x were 0.5 microg/ml (ceftobiprole) and 4 microg/ml (ceftriaxone) in a penicillin- and ceftriaxone-resistant isolate [10].
  • With low concentrations of cefotaxime, transformants of the sensitive S. pneumoniae R6 strain could be selected containing pbpX genes from either S. mitis NCTC 10712 or S. oralis M3, demonstrating that genetic exchange can already occur between beta-lactam-sensitive species [2].
  • After induction with isopropyl beta-d-thiogalactopyranoside, PBP 2x was expressed as one of the major cellular proteins [3].

Analytical, diagnostic and therapeutic context of pbpX


  1. Nucleotide sequences of the pbpX genes encoding the penicillin-binding proteins 2x from Streptococcus pneumoniae R6 and a cefotaxime-resistant mutant, C506. Laible, G., Hakenbeck, R., Sicard, M.A., Joris, B., Ghuysen, J.M. Mol. Microbiol. (1989) [Pubmed]
  2. Mosaic pbpX genes of major clones of penicillin-resistant Streptococcus pneumoniae have evolved from pbpX genes of a penicillin-sensitive Streptococcus oralis. Sibold, C., Henrichsen, J., König, A., Martin, C., Chalkley, L., Hakenbeck, R. Mol. Microbiol. (1994) [Pubmed]
  3. Penicillin-binding protein 2x of Streptococcus pneumoniae. Expression in Escherichia coli and purification of a soluble enzymatically active derivative. Laible, G., Keck, W., Lurz, R., Mottl, H., Frère, J.M., Jamin, M., Hakenbeck, R. Eur. J. Biochem. (1992) [Pubmed]
  4. Pneumococcal beta-lactam resistance due to a conformational change in penicillin-binding protein 2x. Carapito, R., Chesnel, L., Vernet, T., Zapun, A. J. Biol. Chem. (2006) [Pubmed]
  5. Kinetics of beta-lactam interactions with penicillin-susceptible and -resistant penicillin-binding protein 2x proteins from Streptococcus pneumoniae. Involvement of acylation and deacylation in beta-lactam resistance. Lu, W.P., Kincaid, E., Sun, Y., Bauer, M.D. J. Biol. Chem. (2001) [Pubmed]
  6. Mutations in the active site of penicillin-binding protein PBP2x from Streptococcus pneumoniae. Role in the specificity for beta-lactam antibiotics. Mouz, N., Di Guilmi, A.M., Gordon, E., Hakenbeck, R., Dideberg, O., Vernet, T. J. Biol. Chem. (1999) [Pubmed]
  7. Diversity of substitutions within or adjacent to conserved amino acid motifs of penicillin-binding protein 2X in cephalosporin-resistant Streptococcus pneumoniae isolates. Asahi, Y., Takeuchi, Y., Ubukata, K. Antimicrob. Agents Chemother. (1999) [Pubmed]
  8. Complex relationship between acquisition of beta-lactam resistance and loss of virulence in Streptococcus pneumoniae. Rieux, V., Carbon, C., Azoulay-Dupuis, E. J. Infect. Dis. (2001) [Pubmed]
  9. The crystal structure of the penicillin-binding protein 2x from Streptococcus pneumoniae and its acyl-enzyme form: implication in drug resistance. Gordon, E., Mouz, N., Duée, E., Dideberg, O. J. Mol. Biol. (2000) [Pubmed]
  10. Activities of ceftobiprole and other beta-lactams against Streptococcus pneumoniae clinical isolates from the United States with defined substitutions in penicillin-binding proteins PBP 1a, PBP 2b, and PBP 2x. Davies, T.A., Shang, W., Bush, K. Antimicrob. Agents Chemother. (2006) [Pubmed]
  11. Amino acid mutations essential to production of an altered PBP 2X conferring high-level beta-lactam resistance in a clinical isolate of Streptococcus pneumoniae. Smith, A.M., Klugman, K.P. Antimicrob. Agents Chemother. (2005) [Pubmed]
  12. Deacylation kinetics analysis of Streptococcus pneumoniae penicillin-binding protein 2x mutants resistant to beta-lactam antibiotics using electrospray ionization- mass spectrometry. Di Guilmi, A.M., Mouz, N., Pétillot, Y., Forest, E., Dideberg, O., Vernet, T. Anal. Biochem. (2000) [Pubmed]
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