http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Ehrt, Sabine (검색결과 2 건)
- 무료
- 기관 내 무료
- 유료
-
Woong Park, Sae,Klotzsche, Marcus,Wilson, Daniel J.,Boshoff, Helena I.,Eoh, Hyungjin,Manjunatha, Ujjini,Blumenthal, Antje,Rhee, Kyu,Barry III, Clifton E.,Aldrich, Courtney C.,Ehrt, Sabine,Schnappinger Public Library of Science 2011 PLoS pathogens Vol.7 No.9
<▼1><P>In the search for new drug targets, we evaluated the biotin synthetic pathway of <I>Mycobacterium tuberculosis (Mtb)</I> and constructed an <I>Mtb</I> mutant lacking the biotin biosynthetic enzyme 7,8-diaminopelargonic acid synthase, BioA. In biotin-free synthetic media, <I>ΔbioA</I> did not produce wild-type levels of biotinylated proteins, and therefore did not grow and lost viability. <I>ΔbioA</I> was also unable to establish infection in mice. Conditionally-regulated knockdown strains of <I>Mtb</I> similarly exhibited impaired bacterial growth and viability <I>in vitro</I> and in mice, irrespective of the timing of transcriptional silencing. Biochemical studies further showed that BioA activity has to be reduced by approximately 99% to prevent growth. These studies thus establish that <I>de novo</I> biotin synthesis is essential for <I>Mtb</I> to establish and maintain a chronic infection in a murine model of TB. Moreover, these studies provide an experimental strategy to systematically rank the <I>in vivo</I> value of potential drug targets in <I>Mtb</I> and other pathogens.</P></▼1><▼2><P><B>Author Summary</B></P><P>We evaluated the biotin synthetic pathway of <I>Mycobacterium tuberculosis</I> (<I>Mtb</I>) as a new drug target by first generating an <I>Mtb</I> deletion mutant, <I>ΔbioA</I>, in which the biotin biosynthetic enzyme 7,8-diaminopelargonic acid synthase (BioA) has been inactivated. This mutant grew in the presence of biotin or <I>des</I>-thiobiotin, but not with an intermediate of the biotin biosynthesis pathway that requires BioA to be converted into biotin. Without exogenous biotin or <I>des</I>-thiobiotin, <I>ΔbioA,</I> was unable to produce biotinylated proteins, which are required for the biosynthesis of fatty acids, and thus died in biotin-free media. Using a regulatable promoter and different ribosome binding sequences we next constructed tightly controlled TetON mutants, in which expression of BioA could be induced with tetracyclines, but was inhibited in their absence. Characterization of these mutants during infections demonstrated that <I>de novo</I> biotin synthesis is not only required to establish infections but also to maintain bacterial persistence. Inhibition of BioA or other enzymes of the biotin biosynthesis pathways could thus be used to kill <I>Mtb</I> during both acute and chronic infections. Biochemical and immunological analyses of different <I>Mtb</I> mutants indicate that drugs targeting BioA would have to inactive approximately 99% of its activity to be effective.</P></▼2>
-
Boshoff, Helena I. M.,Xu, Xia,Tahlan, Kapil,Dowd, Cynthia S.,Pethe, Kevin,Camacho, Luis R.,Park, Tae-Ho,Yun, Chang-Soo,Schnappinger, Dirk,Ehrt, Sabine,Williams, Kerstin J.,Barry III, Clifton E. American Society for Biochemistry and Molecular Bi 2008 The Journal of biological chemistry Vol.283 No.28
<P>Despite the presence of genes that apparently encode NAD salvage-specific enzymes in its genome, it has been previously thought that Mycobacterium tuberculosis can only synthesize NAD de novo. Transcriptional analysis of the de novo synthesis and putative salvage pathway genes revealed an up-regulation of the salvage pathway genes in vivo and in vitro under conditions of hypoxia. [14C]Nicotinamide incorporation assays in M. tuberculosis isolated directly from the lungs of infected mice or from infected macrophages revealed that incorporation of exogenous nicotinamide was very efficient in in vivo-adapted cells, in contrast to cells grown aerobically in vitro. Two putative nicotinic acid phosphoribosyltransferases, PncB1 (Rv1330c) and PncB2 (Rv0573c), were examined by a combination of in vitro enzymatic activity assays and allelic exchange studies. These studies revealed that both play a role in cofactor salvage. Mutants in the de novo pathway died upon removal of exogenous nicotinamide during active replication in vitro. Cell death is induced by both cofactor starvation and disruption of cellular redox homeostasis as electron transport is impaired by limiting NAD. Inhibitors of NAD synthetase, an essential enzyme common to both recycling and de novo synthesis pathways, displayed the same bactericidal effect as sudden NAD starvation of the de novo pathway mutant in both actively growing and nonreplicating M. tuberculosis. These studies demonstrate the plasticity of the organism in maintaining NAD levels and establish that the two enzymes of the universal pathway are attractive chemotherapeutic targets for active as well as latent tuberculosis.</P>
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
