Journal of Bacteriology
0021-9193
1098-5530
Mỹ
Cơ quản chủ quản: AMER SOC MICROBIOLOGY , American Society for Microbiology
Lĩnh vực:
MicrobiologyMolecular Biology
Phân tích ảnh hưởng
Thông tin về tạp chí
The Journal of Bacteriology® (JB) publishes primary-research articles that probe fundamental processes in bacteria, archaea, and their viruses and the molecular mechanisms by which they interact with each other and with their hosts and their environments.
Các bài báo tiêu biểu
Characterization of a periplasmic 3':5'-cyclic nucleotide phosphodiesterase gene, cpdP, from the marine symbiotic bacterium Vibrio fischeri Vibrio fischeri, a marine bacterium that forms a bioluminescent symbiosis with certain fish and squids, exhibits the unusual attribute of growth on 3':5'-cyclic AMP (cAMP), apparently through the activity of a 3':5'-cyclic nucleotide phosphodiesterase (3':5'-CNP) with exceptionally high activity. The V. fischeri 3':5'-CNP is located in the periplasm, a novel cellular location for this enzyme in bacteria. To gain insight into the physiological function of this enzyme, we cloned the gene (designated cpdP) encoding it from V. fischeri MJ-1. This is the first bacterial 3':5'-CNP gene to be cloned. Sequencing and analysis of the 1.26-kb cpdP locus revealed a single open reading frame specifying a protein of 330 amino acid residues, including a 22-amino-acid leader peptide. The putative cpdP promoter contained a reasonable -10 promoter region (TATTAT) but contained no obvious -35 region; instead, a 12-bp inverted repeat (TTAAATATTTAA) occurred just upstream of this location. A possible rho-independent transcriptional terminator with a calculated free energy of -21.2 kcal.mol-1 (ca. -88.7 kJ.mol-1) followed the CpdP protein coding sequence. The predicted subunit molecular weight of 33,636 for the mature CpdP protein (36,087 less 2,451 for the leader peptide) was consistent with the molecular weight of 34,000 estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The deduced amino acid sequence of the CpdP protein exhibited 30.3% identity with that of the low-affinity 3':5'-CNP (PDE1) of Saccharomyces cerevisiae and 33.6% identity with that of the extracellular 3':5'-CNP of Dictyostelium discoideum. The residue identities clustered in two regions, residues 100 to 146 and 238 to 269, which contained 30 of the 33 amino acids conserved in all three proteins, 4 of which were histidines. A gene replacement mutant of V. fischeri MJ-1 containing a 0.45-kb BglII deletion within the cpdP gene lacked periplasmic 3':5'-CNP activity and did not grow on cAMP, confirming for V. fischeri the relationship among cpdP, synthesis of the periplasmic 3':5'-CNP, and growth on cAMP. The mutant exhibited no obvious sensitivity to high extracellular concentrations of cAMP (5 and 10 mM), suggesting that the enzyme does not play a role in defense against extracellular cAMP.
Tập 175 Số 15 - Trang 4615-4624 - 1993
Cloning, nucleotide sequence, and expression of a gene encoding an adhesin subunit protein of Helicobacter pylori Gene hpaA, which codes for the receptor-binding subunit of the N-acetylneuraminyllactose-binding fibrillar hemagglutinin (NLBH) of Helicobacter pylori, was cloned and sequenced. The protein expressed by hpaA, designated HpaA, was identified as the adhesin subunit on the basis of its fetuin-binding activity and its reactivity with a polyclonal, monospecific rabbit serum prepared against NLBH purified from H. pylori. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis and Western blots (immunoblots) showed that the cloned adhesin has the same molecular weight (20,000) as that found on H. pylori. Also, HpaA contains a short sequence of amino acids (KRTIQK) which are all either identical or functionally similar to those which compose the sialic acid-binding motif of Escherichia coli SfaS, K99, and CFA/I. Affinity-purified antibody specific for a 12-residue synthetic peptide that included this sequence blocked the hemagglutinating activity of H. pylori and was shown by immuno-gold electron microscopy to react with almost transparent material on unstained H. pylori cells, which is consistent with previous observations concerning the location and morphology of the NLBH.
Tập 175 Số 3 - Trang 674-683 - 1993
Tryptophan auxotrophs of Rhizobium japonicum Eleven tryptophan-requiring mutants of Rhizobium japonicum I-110 ARS were isolated after nitrous acid mutagenesis and fell into five groups based on characterization by supplementation with intermediates and enzyme assays.
Tập 156 Số 3 - Trang 1356-1358 - 1983
Dual Repression by Fe <sup>2+</sup> -Fur and Mn <sup>2+</sup> -MntR of the <i>mntH</i> Gene, Encoding an NRAMP-Like Mn <sup>2+</sup> Transporter in <i>Escherichia coli</i> ABSTRACT
The uptake of Mn
2+
, a cofactor for several enzymes in
Escherichia coli
, is mediated by MntH, a proton-dependent metal transporter, which also recognizes Fe
2+
with lower affinity. MntH belongs to the NRAMP family of eukaryotic Fe
2+
and Mn
2+
transporters. In
E. coli
strains with chromosomal
mntH-lacZ
fusions,
mntH
was partially repressed by both Mn
2+
and Fe
2+
. Inactivation of
fur
resulted in the loss of Fe
2+
-dependent repression of
mntH
transcription, demonstrating that Fe
2+
repression depends on the global iron regulator Fur. However, these
fur
mutants still showed Mn
2+
-dependent repression of
mntH
. The Mn
2+
-responsive transcriptional regulator of
mntH
was identified as the gene product of
o155
(renamed MntR).
mntR
mutants were impaired in Mn
2+
but not Fe
2+
repression of
mntH
transcription. Binding of purified MntR to the
mntH
operator was manganese dependent. The binding region was localized by DNase I footprinting analysis and covers a nearly perfect palindrome. The Fur binding site, localized within 22 nucleotides of the
mntH
operator by in vivo operator titration assays, resembles the Fur-box consensus sequence.
Tập 183 Số 16 - Trang 4806-4813 - 2001
ZupT Is a Zn(II) Uptake System in <i>Escherichia coli</i> ABSTRACT
Escherichia coli zupT
(
ygiE
), encoding a ZIP family member, mediated zinc uptake. Growth of cells disrupted in both
zupT
and the
znuABC
operon was inhibited by EDTA at a much lower concentration than a single mutant or the wild type. Cells expressing ZupT from a plasmid exhibited increased uptake of
65
Zn
2+
.
Tập 184 Số 3 - Trang 864-866 - 2002
ZitB (YbgR), a Member of the Cation Diffusion Facilitator Family, Is an Additional Zinc Transporter in <i>Escherichia coli</i> ABSTRACT
The
Escherichia coli zitB
gene encodes a Zn(II) transporter belonging to the cation diffusion facilitator family. ZitB is specifically induced by zinc. ZitB expression on a plasmid rendered
zntA
-disrupted
E. coli
cells more resistant to zinc, and the cells exhibited reduced accumulation of
65
Zn, suggesting ZitB-mediated efflux of zinc.
Tập 183 Số 15 - Trang 4664-4667 - 2001
Cloning and Functional Analysis of the <i>pbr</i> Lead Resistance Determinant of <i>Ralstonia metallidurans</i> CH34 ABSTRACT
The lead resistance operon,
pbr
, of
Ralstonia metallidurans
(formerly
Alcaligenes eutrophus
) strain CH34 is unique, as it combines functions involved in uptake, efflux, and accumulation of Pb(II). The
pbr
lead resistance locus contains the following structural resistance genes: (i)
pbrT
, which encodes a Pb(II) uptake protein; (ii)
pbrA
, which encodes a P-type Pb(II) efflux ATPase; (iii)
pbrB
, which encodes a predicted integral membrane protein of unknown function; and (iv)
pbrC
, which encodes a predicted prolipoprotein signal peptidase. Downstream of
pbrC
, the
pbrD
gene, encoding a Pb(II)-binding protein, was identified in a region of DNA, which was essential for functional lead sequestration. Pb(II)-dependent inducible transcription of
pbrABCD
from the
PpbrA
promoter is regulated by PbrR, which belongs to the MerR family of metal ion-sensing regulatory proteins. This is the first report of a mechanism for specific lead resistance in any bacterial genus.
Tập 183 Số 19 - Trang 5651-5658 - 2001
ZntB Is a Novel Zn <sup>2+</sup> Transporter in <i>Salmonella enterica</i> Serovar Typhimurium ABSTRACT
A Zn
2+
transport system encoded by the
zntB
locus of
Salmonella enterica
serovar Typhimurium has been identified. The protein encoded by this locus is homologous to the CorA family of Mg
2+
transport proteins and is widely distributed among the eubacteria. Mutations at
zntB
confer an increased sensitivity to the cytotoxic effects of Zn
2+
and Cd
2+
, a phenotype that suggests that the encoded protein mediates the efflux of both cations. A direct analysis of transport activity identified a capacity for Zn
2+
efflux. These data identify ZntB as a zinc efflux pathway in the enteric bacteria and assign a new function to the CorA family of cation transporters.
Tập 184 Số 16 - Trang 4369-4373 - 2002
Solubilization of Escherichia coli nitrate reductase by a membrane-bound protease Nitrate reductase extracted from the membrane of Escherichia coli by alkaline heat treatment was purified to homogeneity and used to prepare specific antibody. Nitrate reductase, precipitated by this antibody from Triton extracts of the membrane, contained a third subunit not present in the purified enzyme used to prepare the antibody. Nitrate reductase precipitated by antibody from alkaline heat extracts was composed of peptide fragments of various sizes. These fragments were produced by a membrane-bound protease which was activated by alkaline pH and heat. It is the action of this protease that releases the enzyme from the membrane, as shown by the observations that protease inhibitors decreased the amount of solubilization of the enzyme, and the enzyme remaining in the membrane after heating showed much less proteolytic cleavage than that which was released.
Tập 121 Số 3 - Trang 1102-1110 - 1975
Mycoplasma phosphoenolpyruvate-dependent sugar phosphotransferase system: glucose-negative mutant and regulation of intracellular cyclic AMP Glucose-negative mutants of Mycoplasma capricolum were selected for growth on fructose in the presence of the toxic glucose analog alpha-methyl-D-glucopyranoside. The mutants are defective in the phosphoenolpyruvate:sugar phosphotransferase system for glucose. One mutant, pts-4, was studied in detail. It lacks the glucose-specific, membrane-bound enzyme II, IIGlc, as well as the general, low-molecular-weight, phosphocarrier protein, HPr. In place of the latter, however, it has a fructose-specific protein, HPrFru. Consistent with these changes, the mutant lost the ability to grow on glucosamine and maltose but retained its ability to grow on sucrose. In the glucose-negative mutant, glucose did not regulate the intracellular concentration of cyclic AMP. The intracellular concentration of cyclic AMP in M. capricolum is regulated by the presence of metabolizable sugars. In the wild-type, both glucose and fructose reduced the intracellular concentration of cyclic AMP; however, in the glucose-negative mutant, glucose no longer regulated the intracellular level of cyclic AMP.
Tập 133 Số 1 - Trang 203-209 - 1978