scholarly journals Molecular and Structural Analysis of Mosaic Variants of Penicillin-Binding Protein 2 Conferring Decreased Susceptibility to Expanded-Spectrum Cephalosporins inNeisseria gonorrhoeae: Role of Epistatic Mutations

Biochemistry ◽  
2010 ◽  
Vol 49 (37) ◽  
pp. 8062-8070 ◽  
Author(s):  
Joshua Tomberg ◽  
Magnus Unemo ◽  
Christopher Davies ◽  
Robert A. Nicholas
Keyword(s):  
Structural Analysis ◽  
Binding Protein ◽  
Penicillin Binding Protein

scholarly journals A Low-Affinity Penicillin-Binding Protein 2x Variant Is Required for Heteroresistance in Streptococcus pneumoniae

2014 ◽  
Vol 58 (7) ◽  
pp. 3934-3941 ◽  
Author(s):  
Hansjürg Engel ◽  
Moana Mika ◽  
Dalia Denapaite ◽  
Regine Hakenbeck ◽  
Kathrin Mühlemann ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Abc Transporter ◽  
Binding Protein ◽  
Population Analysis ◽  
Resistance Testing ◽  
Penicillin Binding Protein ◽  
Secondary Resistance ◽  
Content Type ◽  
Abc Transporter Genes

ABSTRACTHeteroresistance to penicillin inStreptococcus pneumoniaeis the ability of subpopulations to grow at a higher antibiotic concentration than expected from the MIC. This may render conventional resistance testing unreliable and lead to therapeutic failure. We investigated the role of the primary β-lactam resistance determinants, penicillin-binding protein 2b (PBP2b) and PBP2x, and the secondary resistance determinant PBP1a in heteroresistance to penicillin. Transformants containing PBP genes from the heteroresistant strain Spain23F2349in the nonheteroresistant strain R6 background were tested for heteroresistance by population analysis profiling (PAP). We found thatpbp2x, but notpbp2borpbp1aalone, conferred heteroresistance to R6. However, a change ofpbp2xexpression was not observed, and therefore, expression does not correlate with an increased proportion of resistant subpopulations. In addition, the influence of the CiaRH system, mediating PBP-independent β-lactam resistance, was assessed by PAP onciaRdisruption mutants but revealed no heteroresistant phenotype. We also showed that the highly resistant subpopulations (HOM*) of transformants containing low-affinitypbp2xundergo an increase in resistance upon selection on penicillin plates that partially reverts after passaging on selection-free medium. Shotgun proteomic analysis showed an upregulation of phosphate ABC transporter subunit proteins encoded bypstS,phoU,pstB, andpstCin these highly resistant subpopulations. In conclusion, the presence of low-affinitypbp2xenables certain pneumococcal colonies to survive in the presence of β-lactams. Upregulation of phosphate ABC transporter genes may represent a reversible adaptation to antibiotic stress.

Catalytic Mechanism of theStreptomycesK15dd-Transpeptidase/Penicillin-Binding Protein Probed by Site-Directed Mutagenesis and Structural Analysis†,‡

Biochemistry ◽  
2003 ◽  
Vol 42 (10) ◽  
pp. 2895-2906 ◽  
Author(s):  
Noureddine Rhazi ◽  
Paulette Charlier ◽  
Dominique Dehareng ◽  
Danièle Engher ◽  
Marcel Vermeire ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Catalytic Mechanism ◽  
Binding Protein ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Penicillin Binding Protein

scholarly journals Identification and Characterization of the Penicillin-Binding Protein 2a of Streptococcus pneumoniae and Its Possible Role in Resistance to β-Lactam Antibiotics

2000 ◽  
Vol 44 (6) ◽  
pp. 1745-1748 ◽  
Author(s):  
Genshi Zhao ◽  
Timothy I. Meier ◽  
Joann Hoskins ◽  
Kelly A. McAllister
Keyword(s):  
Streptococcus Pneumoniae ◽  
Binding Protein ◽  
Penicillin Resistance ◽  
Penicillin Binding Protein ◽  
Insertional Mutant ◽  
Identification And Characterization

ABSTRACT To further understand the role of penicillin-binding protein 2a (PBP 2a) of Streptococcus pneumoniae in penicillin resistance, we confirmed the identity of the protein as PBP 2a. The PBP 2a protein migrated electrophoretically to a position corresponding to that of PBP 2x, PBP 2a, and PBP 2b of S. pneumoniae and was absent in a pbp2ainsertional mutant of S. pneumoniae. We found that the affinities of PBP 2a for penicillins were lower than for cephalosporins and a carbapenem. When compared with other S. pneumoniae PBPs, PBP 2a exhibited lower affinities for β-lactam antibiotics, especially penicillins. Therefore, PBP 2a is a low-affinity PBP for β-lactam antibiotics in S. pneumoniae.

scholarly journals Role of the Escherichia coli SurA Protein in Stationary-Phase Survival

1998 ◽  
Vol 180 (21) ◽  
pp. 5704-5711 ◽  
Author(s):  
Sara W. Lazar ◽  
Marta Almirón ◽  
Antonio Tormo ◽  
Roberto Kolter
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Stationary Phase ◽  
Binding Protein ◽  
Luria Bertani ◽  
Penicillin Binding Protein ◽  
Prolyl Isomerase ◽  
Peptidyl Prolyl Isomerase ◽  
Stationary Phase Survival

ABSTRACT SurA is a periplasmic peptidyl-prolyl isomerase required for the efficient folding of extracytoplasmic proteins. Although thesurA gene had been identified in a screen for mutants that failed to survive in stationary phase, the role played by SurA in stationary-phase survival remained unknown. The results presented here demonstrate that the survival defect of surA mutants is due to their inability to grow at elevated pH in the absence of ςS. When cultures of Escherichia coli were grown in peptide-rich Luria-Bertani medium, the majority of the cells lost viability during the first two to three days of incubation in stationary phase as the pH rose to pH 9. At this time the surviving cells resumed growth. In cultures of surA rpoS double mutants the survivors lysed as they attempted to resume growth at the elevated pH. Cells lacking penicillin binding protein 3 and ςS had a survival defect similar to that of surA rpoS double mutants, suggesting that SurA foldase activity is important for the proper assembly of the cell wall-synthesizing apparatus.

Determination of the Role of the Carboxyl-terminal Leucine-122 in FMN-binding Protein by Mutational and Structural Analysis

2007 ◽  
Vol 141 (4) ◽  
pp. 459-468 ◽  
Author(s):  
M. Kitamura ◽  
K. Terakawa ◽  
H. Inoue ◽  
T. Hayashida ◽  
K. Suto ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Binding Protein ◽  
Carboxyl Terminal
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