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1.
PLoS Pathog ; 15(9): e1007972, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31487328

RESUMO

The biogenesis of bacterial cell-envelope polysaccharides requires the translocation, across the plasma membrane, of sugar sub-units that are produced inside the cytoplasm. To this end, the hydrophilic sugars are anchored to a lipid phosphate carrier (undecaprenyl phosphate (C55-P)), yielding membrane intermediates which are translocated to the outer face of the membrane. Finally, the glycan moiety is transferred to a nascent acceptor polymer, releasing the carrier in the "inactive" undecaprenyl pyrophosphate (C55-PP) form. Thus, C55-P is generated through the dephosphorylation of C55-PP, itself arising from either de novo synthesis or recycling. Two types of integral membrane C55-PP phosphatases were described: BacA enzymes and a sub-group of PAP2 enzymes (type 2 phosphatidic acid phosphatases). The human pathogen Helicobacter pylori does not contain BacA homologue but has four membrane PAP2 proteins: LpxE, LpxF, HP0350 and HP0851. Here, we report the physiological role of HP0851, renamed HupA, via multiple and complementary approaches ranging from a detailed biochemical characterization to the assessment of its effect on cell envelope metabolism and microbe-host interactions. HupA displays a dual function as being the main C55-PP pyrophosphatase (UppP) and phosphatidylglycerol phosphate phosphatase (PGPase). Although not essential in vitro, HupA was essential in vivo for stomach colonization. In vitro, the remaining UppP activity was carried out by LpxE in addition to its lipid A 1-phosphate phosphatase activity. Both HupA and LpxE have crucial roles in the biosynthesis of several cell wall polysaccharides and thus constitute potential targets for new therapeutic strategies.


Assuntos
Proteínas da Membrana Bacteriana Externa/metabolismo , Helicobacter pylori/metabolismo , Sequência de Aminoácidos , Animais , Proteínas da Membrana Bacteriana Externa/fisiologia , Proteínas de Transporte/metabolismo , Membrana Celular/metabolismo , Parede Celular/metabolismo , Proteínas de Ligação a DNA , Escherichia coli/metabolismo , Proteínas de Escherichia coli/metabolismo , Feminino , Helicobacter pylori/patogenicidade , Camundongos , Camundongos Endogâmicos , Testes de Sensibilidade Microbiana , Fosfatidato Fosfatase , Monoéster Fosfórico Hidrolases/metabolismo , Fosfatos de Poli-Isoprenil/metabolismo , Polimixina B/farmacologia , Pirofosfatases/metabolismo , Estômago
2.
RNA ; 22(10): 1560-73, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27495318

RESUMO

The rpsO-pnp operon encodes ribosomal protein S15 and polynucleotide phosphorylase, a major 3'-5' exoribonuclease involved in mRNA decay in Escherichia coli The gene for the SraG small RNA is located between the coding regions of the rpsO and pnp genes, and it is transcribed in the opposite direction relative to the two genes. No function has been assigned to SraG. Multiple levels of post-transcriptional regulation have been demonstrated for the rpsO-pnp operon. Here we show that SraG is a new factor affecting pnp expression. SraG overexpression results in a reduction of pnp expression and a destabilization of pnp mRNA; in contrast, inhibition of SraG transcription results in a higher level of the pnp transcript. Furthermore, in vitro experiments indicate that SraG inhibits translation initiation of pnp Together, these observations demonstrate that SraG participates in the post-transcriptional control of pnp by a direct antisense interaction between SraG and PNPase RNAs. Our data reveal a new level of regulation in the expression of this major exoribonuclease.


Assuntos
Proteínas de Escherichia coli/genética , Regulação Bacteriana da Expressão Gênica , Polirribonucleotídeo Nucleotidiltransferase/genética , RNA Bacteriano/genética , RNA Interferente Pequeno/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas de Escherichia coli/metabolismo , Homeostase , Óperon , Polirribonucleotídeo Nucleotidiltransferase/metabolismo , RNA Bacteriano/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA Interferente Pequeno/metabolismo
3.
Antimicrob Agents Chemother ; 57(1): 183-8, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23089751

RESUMO

Acinetobacter baumannii is an opportunistic pathogen that is an important source of nosocomial infections. Production of extended-spectrum ß-lactamases (ESBLs) of the GES type in A. baumannii has been increasingly reported, and some of these GES-type enzymes possess some carbapenemase activity. Our aim was to analyze the resistance determinants and the clonal relationships of carbapenem-nonsusceptible A. baumannii clinical isolates recovered from hospitals in Kuwait. A total of 63 isolates were analyzed, and all were found to be positive for bla(GES)-type genes. One isolate harbored the bla(GES-14) gene encoding an ESBL with significant carbapenemase activity, whereas the other isolates harbored the bla(GES-11) ESBL gene. Thirty-three isolates coharbored the bla(OXA-23) and bla(GES-11) genes. Analyses of the genetic locations indicated that the bla(GES-11/-14) genes were plasmid located. It is noteworthy that the bla(OXA-23) and bla(GES-11) genes were colocated onto a single plasmid. Nine different pulsotypes were observed among the 63 isolates. This study showed the emergence of GES-type ESBLs in A. baumannii in Kuwait, further suggesting that the Middle East region might be a reservoir for carbapenemase-producing A. baumannii.


Assuntos
Infecções por Acinetobacter/tratamento farmacológico , Acinetobacter baumannii/efeitos dos fármacos , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Carbapenêmicos/farmacologia , Plasmídeos , beta-Lactamases/genética , Infecções por Acinetobacter/epidemiologia , Infecções por Acinetobacter/microbiologia , Acinetobacter baumannii/genética , Acinetobacter baumannii/isolamento & purificação , Proteínas de Bactérias/classificação , Técnicas de Tipagem Bacteriana , Eletroforese em Gel de Campo Pulsado , Humanos , Kuweit/epidemiologia , Resistência beta-Lactâmica/efeitos dos fármacos , Resistência beta-Lactâmica/genética , beta-Lactamases/classificação
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