scholarly journals Imipenem resistance in Klebsiella pneumoniae is associated with the combination of ACT-1, a plasmid-mediated AmpC beta-lactamase, and the foss of an outer membrane protein.

1997 ◽  
Vol 41 (3) ◽  
pp. 563-569 ◽  
Author(s):  
P A Bradford ◽  
C Urban ◽  
N Mariano ◽  
S J Projan ◽  
J J Rahal ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Klebsiella Pneumoniae ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Major Outer Membrane Protein ◽  
Beta Lactamase ◽  
Gene Encoding ◽  
Beta Lactamases ◽  
Imipenem Resistance ◽  
High Level

Six Escherichia coli and 12 Klebsiella pneumoniae isolates from a single hospital expressed a common beta-lactamase with a pI of approximately 9.0 and were resistant to cefoxitin and cefotetan (MIC ranges, 64 to > 128 and 16 to > 128 micrograms/ml, respectively). Seventeen of the 18 strains produced multiple beta-lactamases. Most significantly, three K. pneumoniae strains were also resistant to imipenem (MICs, 8 to 32 micrograms/ml). Spectrophotometric beta-lactamase assays with purified enzyme indicated hydrolysis of cephamycins, in addition to cephaloridine and benzylpenicillin. The 4ene encoding the pI 9.0 beta-lactamase (designated ACT-1 for AmpC type) was cloned and sequenced, which revealed an ampC-type beta-lactamase gene that originated from Enterobacter cloacae and that had 86% sequence homology to the P99 beta-lactamase and 94% homology to the partial sequence of MIR-1. Southern blotting revealed that the gene encoding ACT-1 was on a large plasmid in some of the K. pneumoniae strains as well as on the chromosomes of all of the strains, suggesting that the gene is located on an easily mobilized element. Outer membrane protein profiles of the K. pneumoniae strains revealed that the three imipenem-resistant strains were lacking a major outer membrane protein of approximately 42 kDa which was present in the imipenem-susceptible strains. ACT-1 is the first plasmid-mediated AmpC-type beta-lactamase derived from Enterobacter which has been completely sequenced. This work demonstrates that in addition to resistance to cephamycins, imipenem resistance can occur in K. pneumoniae when a high level of the ACT-1 beta-lactamase is produced in combination with the loss of a major outer membrane protein.

scholarly journals Conservation of msp, the gene encoding the major outer membrane protein of oral Treponema spp.

1997 ◽  
Vol 179 (4) ◽  
pp. 1082-1089 ◽  
Author(s):  
J C Fenno ◽  
G W Wong ◽  
P M Hannam ◽  
K H Müller ◽  
W K Leung ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Major Outer Membrane Protein ◽  
Gene Encoding

scholarly journals In Vivo Transfer of Plasmid-Encoded ACC-1 AmpC from Klebsiella pneumoniae to Escherichia coli in an Infant and Selection of Impermeability to Imipenem in K. pneumoniae

2005 ◽  
Vol 49 (8) ◽  
pp. 3562-3565 ◽  
Author(s):  
Philippe Bidet ◽  
Béatrice Burghoffer ◽  
Valérie Gautier ◽  
Naïma Brahimi ◽  
Patricia Mariani-Kurkdjian ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Membrane Protein ◽  
Klebsiella Pneumoniae ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Major Outer Membrane Protein ◽  
In Vivo Selection ◽  
Selection Of

ABSTRACT We describe in vivo selection of a Klebsiella pneumoniae strain with diminished imipenem susceptibility attributable to plasmid-encoded ACC-1 β-lactamase production and loss of a 36-kDa major outer membrane protein, together with transfer of this plasmid from K. pneumoniae to Escherichia coli in a Tunisian infant.

scholarly journals Mutation of the gene encoding a major outer-membrane protein in Xanthomonas campestris pv. campestris causes pleiotropic effects, including loss of pathogenicity

Microbiology ◽  
2010 ◽  
Vol 156 (9) ◽  
pp. 2842-2854 ◽  
Author(s):  
Yih-Yuan Chen ◽  
Chieh-Hao Wu ◽  
Juey-Wen Lin ◽  
Shu-Fen Weng ◽  
Yi-Hsiung Tseng
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Xanthomonas Campestris ◽  
Extracellular Enzymes ◽  
Surface Deformation ◽  
Cell Signalling ◽  
Cell Aggregation ◽  
Major Outer Membrane Protein ◽  
Gene Encoding

Xanthomonas campestris pv. campestris (Xcc) is the phytopathogen that causes black rot in crucifers. The xanthan polysaccharide and extracellular enzymes produced by this organism are virulence factors, the expression of which is upregulated by Clp (CRP-like protein) and DSF (diffusible signal factor), which is synthesized by RpfF. It is also known that biofilm formation/dispersal, regulated by the effect of controlled synthesis of DSF on cell–cell signalling, is required for virulence. Furthermore, a deficiency in DSF causes cell aggregation with concomitant production of a gum-like substance that can be dispersed by addition of DSF or digested by exogenous endo-β-1,4-mannanase expressed by Xcc. In this study, Western blotting of proteins from a mopB mutant (XcMopB) showed Xcc MopB to be the major outer-membrane protein (OMP); Xcc MopB shared over 97 % identity with homologues from other members of Xanthomonas. Similarly to the rpfF mutant, XcMopB formed aggregates with simultaneous production of a gummy substance, but these aggregates could not be dispersed by DSF or endo-β-1,4-mannanase, indicating that different mechanisms were involved in aggregation. In addition, XcMopB showed surface deformation, altered OMP composition, impaired xanthan production, increased sensitivity to stressful conditions including SDS, elevated temperature and changes in pH, reduced adhesion and motility and defects in pathogenesis. The finding that the major OMP is required for pathogenicity is unprecedented in phytopathogenic bacteria.

Sequence of the gene encoding the major outer membrane protein of the mouse pneumonitis biovar of Chlamydia trachomatis

Gene ◽  
1991 ◽  
Vol 106 (1) ◽  
pp. 137-138 ◽  
Author(s):  
Thomas J. Fielder ◽  
Sukumar Pal ◽  
Ellena M. Peterson ◽  
Luis M. de la Maza
Keyword(s):  
Chlamydia Trachomatis ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Major Outer Membrane Protein ◽  
Gene Encoding
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