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Query: UMLS:C0519030 (Klebsiella)
 21,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The nucleotide sequences of genes homologous to the Klebsiella pneumoniae nifEN genes have been determined in Bradyrhizobium japonicum 110. The coding regions for the nifE and nifN consist, respectively, of 1641 and 1407 nucleotides. The nifD gene (coding for the beta-subunit of dinitrogenase) and nifE are linked, and separated by 95 nucleotides. In the region of 12 nucleotides that separates nifE from nifN the stop codon for nifE overlaps the putative ribosome binding site for nifN. In contrast to Klebsiella and Azotobacter vinelandii, the B. japonicum nifEN genes are linked to the nifDK genes in the same operon. Comparison of dinitrogenase polypeptides (nifDK products) and the polypeptides of the nifE and nifN genes reveals considerable homology between nifD and nifE, and between nifK and nifN. Several protein domains, containing highly conserved cysteine residues, are conserved among the gene products of nifD, nifK, nifE and nifN. This result allows us to propose a probable evolutionary pathway for the common origin of these genes.
Mol Gen Genet 1990 Dec
PMID:The nifEN genes participating in FeMo cofactor biosynthesis and genes encoding dinitrogenase are part of the same operon in Bradyrhizobium species. 226 45

In Klebsiella pneumoniae the gene products involved in the degradation of the ketose L-sorbose are encoded in the sor operon. It comprises, besides structural genes for uptake and catabolism, a promoter-proximal gene sorC, encoding a protein SorC of Mr 40 kDa, for which no enzymatic function has been detected. All sor genes are coordinately expressed and inducible by L-sorbose. Polar insertions and frameshift mutations in sorC cause a pleiotropic negative effect on the expression of all other sor genes. This defect is complemented in trans by the wild-type sorC+ allele for frameshift mutations, but not for polar insertions. A single promoter for all sor genes, for which SorC is the activator, thus seems to be located in front of sorC. The repressor activity of SorC was demonstrated by complementation of constitutive sorC alleles with a sorC+ allele leading to inducible expression of all sor genes, including sorC, which, as visualized by the use of a series of lacZ fusions, thus autoregulates its expression, both as an activator and a repressor.
Mol Gen Genet 1990 Nov
PMID:Positive and negative regulation of expression of the L-sorbose (sor) operon by SorC in Klebsiella pneumoniae. 227 38

A gene encoding a positive activator of the expression of extracellular polysaccharide (EPS) synthesis in the phytopathogen Erwinia amylovora has been isolated from a genomic library in Escherichia coli. The presence of the cloned gene in E. coli stimulated transcription of the genes encoding colanic acid biosynthesis and could complement rcsA mutations. Introduction of the gene on a multicopy plasmid into Er. amylovora caused a threefold increase in EPS expression. The nucleotide sequence of the gene (designated rcsA) was determined. This revealed a single open reading frame encoding an RcsA protein of 23-7 kDa. This was confirmed by minicell analysis in E. coli. The predicted amino acid sequence of this RcsA protein showed a high degree of homology to the RcsA protein of Klebsiella aerogenes, demonstrating the existence of a family of related RcsA activator proteins capable of stimulating EPS expression. The protein had no significant homology to known DNA-binding activator proteins, indicating, for the first time, that the RcsA family of activator proteins may stimulate expression of EPS synthesis indirectly by acting on other regulatory proteins.
J Gen Microbiol 1990 Sep
PMID:Molecular cloning, expression and nucleotide sequence of the rcsA gene of Erwinia amylovora, encoding a positive regulator of capsule expression: evidence for a family of related capsule activator proteins. 228 3

We determined the nucleotide sequence of gene 1 of Klebsiella phage K11, which is a member of the T7 group of phages. The largest open reading frame corresponds to a polypeptide with 906 amino acids and a molecular weight of 100,383 daltons. The deduced amino acid sequence of this polypeptide shows 71% homology to the T7 RNA polymerase (the product of T7 gene 1), 72% homology to the T3 RNA polymerase and 27% homology to the SP6 RNA polymerase. Divergent evolution was clearly most pronounced in the amino-terminal portion.
Mol Gen Genet 1990 Apr
PMID:The gene for Klebsiella bacteriophage K11 RNA polymerase: sequence and comparison with the homologous genes of phages T7, T3, and SP6. 237 Aug 50

Several Klebsiella pneumoniae strains which produced enterochelin but not aerobactin were nevertheless sensitive to cloacin DF13. In contrast, a strain of serotype K1:O1 which produced both siderophores was cloacin-resistant. Loss by mutation of the O1 but not K1 antigen rendered this strain cloacin-sensitive, indicating that the O1 antigen prevented access of cloacin to the cloacin/aerobactin receptor. Unlike the K1:O1 strain, the aerobactin-negative strains failed to hybridize in a colony blot assay with an aerobactin receptor gene probe prepared from pColV-K30. However, antisera raised against the 74 kDa pColV-K30 aerobactin receptor cross-reacted with a 76 kDa outer-membrane protein in each K. pneumoniae strain. In addition to the 76 kDa protein, the K1:O1 strain also produced a strongly cross-reacting 74 kDa protein. To determine whether these aerobactin-negative strains could use aerobactin, mutants unable to synthesize siderophores were isolated. Aerobactin promoted the growth of these mutants in iron-deficient media. The evidence presented suggests that some K. pneumoniae strains produce an aerobactin iron-uptake system without apparent production of aerobactin and which is probably based on a 76 kDa receptor, the gene for which does not hybridize with aerobactin receptor gene encoded on pColV-K30.
J Gen Microbiol 1989 Dec
PMID:Novel aerobactin receptor in Klebsiella pneumoniae. 253 99

Klebsiella pneumoniae 1033-5P14 and its P1-sensitive derivative KAY2026 were found to be resistant to lambda although they contained a LamB protein, active as a maltoporin. Sensitive derivatives could only be obtained after introduction of the pTROY9 plasmid which expresses lamB and the corresponding lambda receptor from Escherichia coli K12 at high levels. Lysogenic derivatives from such strains were shown to carry the phage at secondary att sites and to give high titer lysates when induced. The use of lambda plac-Mu hybrid phages allowed the isolation from several operons of lacZ fusions orientated in, or against, the direction of transcription. Such insertions could subsequently be used to isolate stable Hfr strains by allowing homologous recombination to take place between the lac genes in the inserted hybrid phages and those of plasmid F' ts114 lac+ zzf20::Tn10. The Hfr strains were able to transfer K. pneumoniae chromosomal genes and allowed the mapping of such genes. Characteristic differences between this conjugation system and that of Escherichia coli K12 are discussed. The insertions also allowed determination of the direction of transcription of the gut gene, the newly mapped scr gene and of the sor gene cluster encoding enzymes for the metabolism of D-glucitol, sucrose and L-sorbose.
Mol Gen Genet 1989 Feb
PMID:The use of lambda plac-Mu hybrid phages in Klebsiella pneumoniae and the isolation of stable Hfr strains. 254 Apr 16

Two plasmids were isolated containing oppositely oriented gamma-delta insertions between the wild-type transcription initiation site of the nifHDKY operon and the nifH coding sequence. The nifHDKY promoter of Klebsiella pneumoniae, similar to other nitrogen fixation (nif) promoters, normally requires the products of ntrA and nifA for activity. Mutations that allowed constitutive expression of the nifHDKY operon were searched for by transforming a plasmid, containing the regulatory region of this operon followed by an in-frame nifH'-'lacZ fusion, into a Lac- Escherichia coli strain (which contains no nifA) and screening for Lac+ derivatives. The plasmids described here were isolated from such derivatives and directed the constitutive expression of beta-galactosidase. Deletion analysis indicated that gamma-delta promoters other than those transcribing tnpA and tnpR were involved in this expression. Nuclease S1 mapping revealed outward-reading transcription initiation sites in both the gamma end and the delta end of the transposon. Most interestingly, one initiation site on each end was located in corresponding positions within the terminal inverted repeats. The sites were in the center of the longest sequence, of 12 bp, contiguously conserved between the terminal inverted repeats of gamma-delta and the related transposon Tn3. In gamma-delta and Tn3, this sequence has been recently implicated in transposase binding. These results suggest a possible interrelationship between transcription from the "end" promoters and transposition.
Mol Gen Genet 1989 Mar
PMID:Outreading promoters are located at both ends of the gamma-delta transposon. 254 4

Three new Tn5-mutagenized nif genes of Azospirillum brasilense were characterized. The sizes of the restriction fragments and the restriction maps of the cloned nif DNA regions showed that these nif genes are distinct from those reported earlier, e.g. nifHDK, nifE, nifUS, fixABC. The Nif27 mutant was identified as a nifA type regulatory gene of A. brasilense (a) by genetic complementation with nifA of Klebsiella pneumoniae, (b) by the absence of nitrogenase iron protein in western protein blots and (c) by its inability to activate expression of a nifH-lacZ fusion. The growth characteristics of the three mutants showed that none of them is defective in general nitrogen regulatory (ntr) genes. Also, no homology was detected between the three nif DNA regions of the mutants, cloned in pMS188, pMS189 and pMS197, and the K. pneumoniae nif, glnA or ntr genes. In addition, the fixABC genes of Bradyrhizobium japonicum did not show any hybridization with the cloned Azospirillum genes. Unlike the situation in enteric bacteria, the nif genes in A. brasilense are scattered and span a region of about 65 kb.
Mol Gen Genet 1989 Oct
PMID:Identification of a regulatory nifA type gene and physical mapping of cloned new nif regions of Azospirillum brasilense. 255 12

The dha regulon of Klebsiella pneumoniae specifying fermentative dissimilation of glycerol was mobilized by the broad-host-range plasmid RP4:mini Mu and introduced conjugatively into Escherichia coli. The recipient E. coli was enabled to grow anaerobically on glycerol without added hydrogen acceptors, although its cell yield was less than that of K. pneumoniae. The reduced cell yield was probably due to the lack of the coenzyme-B12-dependent glycerol dehydratase of the dha system. This enzyme initiates the first step in an auxiliary pathway for disposal of the extra reducing equivalents from glycerol. The lack of this enzyme would also account for the absence of 1,3-propanediol (a hallmark fermentation product of glycerol) in the spent culture medium. In a control experiment, a large quantity of this compound was detected in a similar culture medium following the growth of K. pneumoniae. The other three known enzymes of the dha system, glycerol dehydrogenase, dihydroxyacetone kinase and 1,3-propanediol oxidoreductase, however, were synthesized at levels comparable to those found in K. pneumoniae. Regulation of the dha system in E. coli appeared to follow the same pattern as in K. pneumoniae: the three acquired enzymes were induced by glycerol, catabolite repressed by glucose, and glycerol dehydrogenase was post-translationally inactivated during the shift from anaerobic to aerobic growth. The means by which the E. coli recipient can achieve redox balance without formation of 1,3-propanediol during anaerobic growth on glycerol remains to be discovered.
J Gen Microbiol 1989 May
PMID:Anaerobic growth of Escherichia coli on glycerol by importing genes of the dha regulon from Klebsiella pneumoniae. 255 47

The role of the Klebsiella pneumoniae PII protein (encoded by glnB) in nitrogen regulation has been studied using two classes of glnB mutants. In Class I mutants PII appears not to be uridylylated in nitrogen-limiting conditions and in Class II mutants PII is not synthesised. The effects of these mutations on expression from nitrogen-regulated promoters indicate that PII is not absolutely required for nitrogen control. Furthermore the uridylylated form of PII (PII-UMP) plays a significant role in the response to changes in nitrogen status by counteracting the effect of PII on NtrB-mediated dephosphorylation of NtrC. PII is not involved in the nif-specific response to changes in nitrogen status mediated by NifL.
Mol Gen Genet 1989 Jun
PMID:The Klebsiella pneumoniae PII protein (glnB gene product) is not absolutely required for nitrogen regulation and is not involved in NifL-mediated nif gene regulation. 257 Mar 49


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