scholarly journals Amino Acid Substitutions of MagA in Klebsiella pneumoniae Affect the Biosynthesis of the Capsular Polysaccharide

PLoS ONE ◽  
2012 ◽  
Vol 7 (10) ◽  
pp. e46783 ◽  
Author(s):  
Tzu-Lung Lin ◽  
Feng-Ling Yang ◽  
An-Suei Yang ◽  
Hung-Pin Peng ◽  
Tsung-Lin Li ◽  
...  
Keyword(s):  
Amino Acid ◽  
Klebsiella Pneumoniae ◽  
Capsular Polysaccharide ◽  
Amino Acid Substitutions

scholarly journals Amino Acid Substitutions of CrrB Responsible for Resistance to Colistin through CrrC in Klebsiella pneumoniae

2016 ◽  
Vol 60 (6) ◽  
pp. 3709-3716 ◽  
Author(s):  
Yi-Hsiang Cheng ◽  
Tzu-Lung Lin ◽  
Yi-Tsung Lin ◽  
Jin-Town Wang
Keyword(s):  
Amino Acid ◽  
Klebsiella Pneumoniae ◽  
Site Directed Mutagenesis ◽  
Amino Acid Substitutions ◽  
Missense Mutations ◽  
Colistin Resistance ◽  
Two Component System ◽  
Content Type ◽  
Carbapenem Resistant ◽  
Elevated Expression

Colistin is a last-resort antibiotic for treatment of carbapenem-resistantKlebsiella pneumoniae. A recent study indicated that missense mutations in the CrrB protein contribute to colistin resistance. In our previous study, mechanisms of colistin resistance were defined in 17 of 26 colistin-resistantK. pneumoniaeclinical isolates. Of the remaining nine strains, eight were highly resistant to colistin. In the present study,crrABsequences were determined for these eight strains. Six separate amino acid substitutions in CrrB (Q10L, Y31H, W140R, N141I, P151S, and S195N) were detected. Site-directed mutagenesis was used to generatecrrBloci harboring individual missense mutations; introduction of the mutated genes into a susceptible strain, A4528, resulted in 64- to 1,024-fold increases in colistin MICs. ThesecrrBmutants showed increased accumulation ofH239_3062,H239_3059,pmrA,pmrC, andpmrHtranscripts by quantitative reverse transcription (qRT)-PCR. Deletion ofH239_3062(but not that ofH239_3059) in the A4528crrB(N141I) strain attenuated resistance to colistin, andH239_3062was accordingly namedcrrC. Similarly, accumulation ofpmrA,pmrC, andpmrHtranscripts induced bycrrB(N141I) was significantly attenuated upon deletion ofcrrC. Complementation ofcrrCrestored resistance to colistin and accumulation ofpmrA,pmrC, andpmrHtranscripts in acrrB(N141I) ΔcrrCstrain. In conclusion, novel individual CrrB amino acid substitutions (Y31H, W140R, N141I, P151S, and S195N) were shown to be responsible for colistin resistance. We hypothesize that CrrB mutations induce CrrC expression, thereby inducing elevated expression of thepmrHFIJKLMoperon andpmrC(an effect mediated via the PmrAB two-component system) and yielding increased colistin resistance.

scholarly journals Ceftazidime-Resistant EnterobacteriaceaeIsolates from Three Polish Hospitals: Identification of Three Novel TEM- and SHV-5-Type Extended-Spectrum β-Lactamases

1998 ◽  
Vol 42 (3) ◽  
pp. 514-520 ◽  
Author(s):  
Marek Gniadkowski ◽  
Ines Schneider ◽  
Renate Jungwirth ◽  
Waleria Hryniewicz ◽  
Adolf Bauernfeind
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Klebsiella Pneumoniae ◽  
Detailed Analysis ◽  
Amino Acid Substitutions ◽  
New Combinations ◽  
Extended Spectrum ◽  
The Family ◽  
Genetic Events ◽  
Esbl Producers

ABSTRACT Twelve ceftazidime-resistant isolates of the familyEnterobacteriaceae (11 Klebsiella pneumoniaeisolates and 1 Escherichia coli isolate) were collected in 1995 from three Polish hospitals located in different cities. All were identified as producers of extended-spectrum β-lactamases (ESBLs). Detailed analysis of their β-lactamase contents revealed that six of them expressed SHV-5-like ESBLs. The remaining six were found to produce three different TEM enzymes, each characterized by a pI value of 6.0 and specified by new combinations of amino acid substitutions. The amino acid substitutions compared to the TEM-1 β-lactamase sequence were Gly238Ser, Glu240Lys, and Thr265Met for TEM-47; Leu21Phe, Gly238Ser, Glu240Lys, and Thr265Met for TEM-48; and Leu21Phe, Gly238Ser, Glu240Lys, Thr265Met, and Ser268Gly for TEM-49. The new TEM β-lactamases, TEM-47, TEM-48, and TEM-49, belong to a subfamily of TEM-2-related enzymes. Genes coding for TEM-47 and TEM-49 could have originated from the TEM-48-encoding sequence by various single genetic events. The new TEM derivatives probably document the already advanced microevolution of ESBLs ongoing in Polish hospitals, in a majority of which no monitoring of ESBL producers was performed before 1996.

scholarly journals VIM-19, a Metallo-β-Lactamase with Increased Carbapenemase Activity from Escherichia coli and Klebsiella pneumoniae

2009 ◽  
Vol 54 (1) ◽  
pp. 471-476 ◽  
Author(s):  
Jose-Manuel Rodriguez-Martinez ◽  
Patrice Nordmann ◽  
Nicolas Fortineau ◽  
Laurent Poirel
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Klebsiella Pneumoniae ◽  
Hydrolytic Activity ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Amino Acid Substitutions ◽  
Class 1 Integron ◽  
Carbapenem Resistant ◽  
Class 1

ABSTRACT Two carbapenem-resistant isolates, one Escherichia coli isolate and one Klebsiella pneumoniae isolate, recovered from an Algerian patient expressed a novel VIM-type metallo-β-lactamase (MBL). The identified bla VIM-19 gene was located on a ca. 160-kb plasmid and located inside a class 1 integron in both isolates. VIM-19 differed from VIM-1 by the Asn215Lys and Ser228Arg substitutions, increasing its hydrolytic activity toward carbapenems. Site-directed mutagenesis experiments showed that both substitutions were necessary for the increased carbapenemase activity of VIM-19. This study indicates that MBLs with enhanced activity toward carbapenems may be obtained as a result of very few amino acid substitutions.

scholarly journals Identification of Genetic Alterations Associated with Acquired Colistin Resistance in Klebsiella pneumoniae Isogenic Strains by Whole-Genome Sequencing

Antibiotics ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 374
Author(s):  
Myeongjin Choi ◽  
Kwan Soo Ko
Keyword(s):  
Amino Acid ◽  
Klebsiella Pneumoniae ◽  
Whole Genome Sequencing ◽  
Candidate Genes ◽  
Genome Sequencing ◽  
Parental Strain ◽  
Genetic Alterations ◽  
Amino Acid Substitutions ◽  
Whole Genome ◽  
Colistin Resistance

The present study was undertaken to find novel genes associated with colistin resistance in Klebsiella pneumoniae. Five colistin-resistant mutants were derived from four colistin-susceptible parental K. pneumoniae strains belonging to different clones. Whole-genome sequencing was performed for the nine K. pneumoniae strains to screen altered candidate genes. Expression levels of genes with amino acid alterations in derivative strains were determined using quantitative real-time Polymerase chain reaction (PCR). Colistin susceptibility was examined in a parental strain complemented with altered candidate genes. Overall, 13 genetic alterations were identified in five pairs of isogenic K. pneumoniae strains. Genetic alterations related to KP1_3468, including the insertion of an IS5-like element in an intergenic or coding region and amino acid substitutions, were identified in three separate derivative strains. Amino acid substitutions and deletion of PhoQ were determined in one derivative strain. With inactivation of CrrA and substituted CrrB, amino acid substitutions and deletion were identified in a repressor of galETK operon (KP1_0061) and hypothetical protein (KP1_3620), respectively. Decreased colistin susceptibility was observed in a parental strain complemented with KP1-0061, but not a KP1-3620 gene. This study demonstrated diverse genetic paths to colistin resistance in K. pneumoniae. Our results suggest that a repressor of galETK operon may play an important role in colistin resistance in K. pneumoniae.

scholarly journals Molecular Epidemiology of Colistin-Resistant, Carbapenemase-Producing Klebsiella pneumoniae in Serbia from 2013 to 2016

2017 ◽  
Vol 61 (5) ◽  
Author(s):  
Katarina Novović ◽  
Anika Trudić ◽  
Snežana Brkić ◽  
Zorica Vasiljević ◽  
Milan Kojić ◽  
...  
Keyword(s):  
Amino Acid ◽  
Klebsiella Pneumoniae ◽  
Molecular Epidemiology ◽  
Gene Transcription ◽  
Stop Codon ◽  
Premature Stop Codon ◽  
Amino Acid Substitutions ◽  
Content Type ◽  
Sequence Types

ABSTRACT Twenty-seven colistin-resistant, carbapenemase-producing Klebsiella pneumoniae isolates were identified from hospitals in Serbia. All isolates were bla CTX-M-15 positive; ST101, ST888, ST437, ST336, and ST307 were bla OXA-48 positive; and ST340 was bla NDM-1 positive. ST307 had an insertion, and ST336 had a premature stop codon in the mgrB gene. Amino acid substitutions were detected in PmrAB of isolates ST101, ST888, ST336, and ST307. The mcr-1 and mcr-2 were not detected. An increase in phoP, phoQ, and pmrK gene transcription was detected for all sequence types.

scholarly journals Characterization of OXA-181, a Carbapenem-Hydrolyzing Class D β-Lactamase from Klebsiella pneumoniae

2011 ◽  
Vol 55 (10) ◽  
pp. 4896-4899 ◽  
Author(s):  
Anaïs Potron ◽  
Patrice Nordmann ◽  
Emilie Lafeuille ◽  
Zaina Al Maskari ◽  
Fatma Al Rashdi ◽  
...  
Keyword(s):  
Amino Acid ◽  
Klebsiella Pneumoniae ◽  
Insertion Sequence ◽  
Amino Acid Substitutions ◽  
Sultanate Of Oman ◽  
Content Type ◽  
Class D

ABSTRACTKlebsiella pneumoniaeKP3 was isolated from a patient transferred from India to the Sultanate of Oman.K. pneumoniaeKP3 was resistant to all β-lactams, including carbapenems, and expressed the carbapenem-hydrolyzing β-lactamase OXA-181, which differs from OXA-48 by four amino acid substitutions. Compared to OXA-48, OXA-181 possessed a very similar hydrolytic profile. TheblaOXA-181gene was located on a 7.6-kb ColE-type plasmid and was linked to the insertion sequence ISEcp1. The ISEcp1-mediated one-ended transposition ofblaOXA-181was also demonstrated.

scholarly journals Characterization of OXA-204, a Carbapenem-Hydrolyzing Class D β-Lactamase from Klebsiella pneumoniae

2012 ◽  
Vol 57 (1) ◽  
pp. 633-636 ◽  
Author(s):  
Anaïs Potron ◽  
Patrice Nordmann ◽  
Laurent Poirel
Keyword(s):  
Amino Acid ◽  
Klebsiella Pneumoniae ◽  
Clinical Isolate ◽  
Broad Spectrum ◽  
Amino Acid Substitutions ◽  
Content Type ◽  
Class D

ABSTRACTAKlebsiella pneumoniaeclinical isolate recovered in Tunisia showed resistance to all β-lactams and decreased susceptibility to carbapenems.K. pneumoniae204 expressed the carbapenem-hydrolyzing β-lactamase OXA-204, differing from OXA-48 by two amino acid substitutions (Gln98His and Thr99Arg) (class D β-lactamase [DBL] numbering). OXA-48 and OXA-204 shared similar resistance profiles, hydrolyzing carbapenems but sparing broad-spectrum cephalosporins. TheblaOXA-204gene was located on a ca. 150-kb IncA/C-type plasmid, which also carried theblaCMY-4gene. TheblaOXA-204gene was associated with an ISEcp1element, whereas theblaOXA-48genes are usually associated with IS1999.

scholarly journals Genetic Analysis of the Nitrogen Assimilation Control Protein from Klebsiella pneumoniae

2010 ◽  
Vol 192 (19) ◽  
pp. 4834-4846 ◽  
Author(s):  
Christopher J. Rosario ◽  
Brian K. Janes ◽  
Robert A. Bender
Keyword(s):  
Crystal Structure ◽  
Amino Acid ◽  
Klebsiella Pneumoniae ◽  
Genetic Analysis ◽  
Binding Sites ◽  
Nitrogen Assimilation ◽  
Transcriptional Regulator ◽  
The Other ◽  
Amino Acid Substitutions ◽  
Control Protein

ABSTRACT The nitrogen assimilation control protein (NAC) from Klebsiella pneumoniae is a typical LysR-type transcriptional regulator (LTTR) in many ways. However, the lack of a physiologically relevant coeffector for NAC and the fact that NAC can carry out many of its functions as a dimer make NAC unusual among the LTTRs. In the absence of a crystal structure for NAC, we analyzed the effects of amino acid substitutions with a variety of phenotypes in an attempt to identify functionally important features of NAC. A substitution that changed the glutamine at amino acid 29 to alanine (Q29A) resulted in a NAC that was seriously defective in binding to DNA. The H26D substitution resulted in a NAC that could bind and repress transcription but not activate transcription. The I71A substitution resulted in a NAC polypeptide that remained monomeric. NAC tetramers can bind to both long and shorter binding sites (like other LTTRs). However, the absence of a coeffector to induce the conformational change needed for the switch from the former to the latter raised a question. Are there two conformations of NAC, analogous to the other LTTRs? The G217R substitution resulted in a NAC that could bind to the longer sites but had difficulty in binding to the shorter sites, and the I222R and A230R substitutions resulted in a NAC that could bind to the shorter sites but had difficulty in binding properly to the longer sites. Thus, there appear to be two conformations of NAC that can freely interconvert in the absence of a coeffector.

Recombinant Variants of Tissue-Type Plasminogen Activator Containing Amino Acid Substitutions in the Finger Domain

1992 ◽  
Vol 68 (06) ◽  
pp. 672-677 ◽  
Author(s):  
Hitoshi Yahara ◽  
Keiji Matsumoto ◽  
Hiroyuki Maruyama ◽  
Tetsuya Nagaoka ◽  
Yasuhiro Ikenaka ◽  
...  
Keyword(s):  
Amino Acid ◽  
Plasminogen Activator ◽  
Half Life ◽  
Tissue Type ◽  
Clot Lysis ◽  
Amino Acid Substitutions ◽  
Wild Type ◽  
Plasma Clot ◽  
Tissue Type Plasminogen Activator ◽  
Type Plasminogen Activator

SummaryTissue-type plasminogen activator (t-PA) is a fibrin-specific agent which has been used to treat acute myocardial infarction. In an attempt to clarify the determinants for its rapid clearance in vivo and high affinity for fibrin clots, we produced five variants containing amino acid substitutions in the finger domain, at amino acid residues 7–9, 10–14, 15–19, 28–33, and 37–42. All the variants had a prolonged half-life and a decreased affinity for fibrin of various degrees. The 37–42 variant demonstrated about a 6-fold longer half-life with a lower affinity for fibrin. Human plasma clot lysis assay estimated the fibrinolytic activity of the 37–42 variant to be 1.4-fold less effective than that of the wild-type rt-PA. In a rabbit jugular vein clot lysis model, doses of 1.0 and 0.15 mg/kg were required for about 70% lysis in the wild-type and 37–42 variant, respectively. Fibrinogen was degraded only when the wild-type rt-PA was administered at a dose of 1.0 mg/kg. These findings suggest that the 37–42 variant can be employed at a lower dosage and that it is a more fibrin-specific thrombolytic agent than the wild-type rt-PA.

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