bluuebunny/crossref_metadata_2025_split huggingface dataset:
The
KlGpa1
Gene Encodes a G-Protein α Subunit That Is a Positive Control Element in the Mating Pathway of the Budding Yeast
Kluyveromyces lactis
Authors: Saviñón-Tejeda Alma L. , Ongay-Larios Laura , Valdés-Rodrı́guez Julián , Coria Roberto 
Published: July 2002

ABSTRACT

The cloning of the gene encoding the KlGpa1p subunit was achieved by standard PCR techniques and by screening a
Kluyveromyces lactis
genomic library using the PCR product as a probe. The full-length open reading frame spans 1,344 nucleotides including the stop codon. The deduced primary structure of the protein (447 amino acid residues) strongly resembles that of Gpa1p, the G-protein α subunit from
Saccharomyces cerevisiae
involved in the mating pheromone response pathway. Nevertheless, unlike disruption of
Gpa1
from
S. cerevisiae
, disruption of
KlGpa1
rendered viable cells with a reduced capacity to mate. Expression of a plasmidic
KlGpa1
copy in a Δ
Klgpa1
mutant restores full mating competence; hence we conclude that KlGpa1p plays a positive role in the mating pathway. Overexpression of the constitutive subunit KlGpa1p(K
364
) (GTP bound) does not induce constitutive mating; instead it partially blocks wild-type mating and is unable to reverse the sterile phenotype of Δ
Klgpa1
mutant cells.
K. lactis
expresses a second Gα subunit, KlGpa2p, which is involved in regulating cyclic AMP levels upon glucose stimulation. This subunit does not rescue Δ
Klgpa1
cells from sterility; instead, overproduction of KlGpa2p slightly reduces the mating of wild-type cells, suggesting cross talk within the pheromone response pathway mediated by KlGpa1p and glucose metabolism mediated by KlGpa2p. The Δ
Klgpa1 ΔKlgpa2
double mutant, although viable, showed the mating deficiency observed in the single Δ
Klgpa1
mutant.
Functional Complementation of Pyran Ring Formation in Actinorhodin Biosynthesis in
Streptomyces coelicolor
A3(2) by Ketoreductase Genes for Granaticin Biosynthesis
Authors: Ichinose Koji , Taguchi Takaaki , Bedford David J. , Ebizuka Yutaka , Hopwood David A. 
Published: July 2002

ABSTRACT

A mutation in
act
VI-ORF1, which controls C-3 reduction in actinorhodin biosynthesis by
Streptomyces coelicolor
, was complemented by
gra
-ORF5 and -ORF6 from the granaticin biosynthetic gene cluster of
Streptomyces violaceoruber
Tü22. It is hypothesized that, while
gra
-ORF5 alone is a ketoreductase for C-9,
gra
-ORF6 gives the enzyme regiospecificity also for C-3.
The Iron- and Temperature-Regulated
cjrBC
Genes of
Shigella
and Enteroinvasive
Escherichia coli
Strains Code for Colicin Js Uptake
Authors: Šmajs David , Weinstock George M. 
Published: July 2002

ABSTRACT

A cosmid library of DNA from colicin Js-sensitive enteroinvasive
Escherichia coli
(EIEC) strain O164 was made in colicin Js-resistant strain
E. coli
VCS257, and colicin Js-sensitive clones were identified. Sensitivity to colicin Js was associated with the carriage of a three-gene operon upstream of and partially overlapping
senB
. The open reading frames were designated
cjrABC
(for colicin Js receptor), coding for proteins of 291, 258, and 753 amino acids, respectively. Tn
7
insertions in any of them led to complete resistance to colicin Js. A near-consensus Fur box was found upstream of
cjrA
, suggesting regulation of the
cjr
operon by iron levels. CjrA protein was homologous to iron-regulated
Pseudomonas aeruginosa
protein PhuW, whose function is unknown; CjrB was homologous to the TonB protein from
Pseudomonas putida
; and CjrC was homologous to a putative outer membrane siderophore receptor from
Campylobacter jejuni.
Cloning experiments showed that the
cjrB
and
cjrC
genes are sufficient for colicin Js sensitivity. Uptake of colicin Js into sensitive bacteria was dependent on the ExbB protein but not on the
E. coli
K-12 TonB and TolA, -B, and -Q proteins. Sensitivity to colicin Js is positively regulated by temperature via the VirB protein and negatively controlled by the iron source through the Fur protein. Among EIEC strains, two types of colicin Js-sensitive phenotypes were identified that differed in sensitivity to colicin Js by 1 order of magnitude. The difference in sensitivity to colicin Js is not due to differences between the sequences of the CjrB and CjrC proteins.
Dual Regulatory Control of a Particle Maturation Function of Bacteriophage P1
Authors: Lehnherr Hansjörg , Jensen Charlotte D. , Stenholm Anne R. , Dueholm Anita 
Published: July 2002

ABSTRACT

A unique arrangement of promoter elements was found upstream of the bacteriophage P1 particle maturation gene (
mat
). A P1-specific late-promoter sequence with conserved elements located at positions −22 and −10 was expected from the function of the gene in phage morphogenesis. In addition to a late-promoter sequence, a −35 element and an operator sequence for the major repressor protein, C1, were found. The −35 and −10 elements constituted an active
Escherichia coli
ς
70
consensus promoter, which was converted into a P1-regulated early promoter by the superimposition of a C1 operator. This combination of early- and late-promoter elements regulates and fine-tunes the expression of the particle maturation gene. During lysogenic growth the gene is turned off by P1 immunity functions. Upon induction of lytic growth, the expression of
mat
starts simultaneously with the expression of other C1-regulated P1 early functions. However, while most of the latter functions are downregulated during late stages of lytic growth the expression of
mat
continues throughout the entire lytic growth cycle of bacteriophage P1. Thus, the maturation function has a head start on the structural components of the phage particle.
Extragenic Suppressors of Growth Defects inmsbB Salmonella
Authors: Murray Sean R. , Bermudes David , de Felipe Karim Suwwan , Low K. Brooks 
Published: July 2002

ABSTRACTLipid A, a potent endotoxin which can cause septic shock, anchors lipopolysaccharide (LPS) into the outer leaflet of the outer membrane of gram-negative bacteria. MsbB acylates (KDO)2-(lauroyl)-lipid IV-A with myristate during lipid A biosynthesis. Reports of knockouts of themsbBgene describe effects on virulence but describe no evidence of growth defects inEscherichia coliK-12 orSalmonella. Our data confirm the general lack of growth defects inmsbB E. coliK-12. In contrast,msbB Salmonella entericaserovar Typhimurium exhibits marked sensitivity to galactose-MacConkey and 6 mM EGTA media. At 37°C in Luria-Bertani (LB) broth,msbB Salmonellacells elongate, form bulges, and grow slowly.msbB Salmonellagrow well on LB-no salt (LB-0) agar; however, under specific shaking conditions in LB-0 broth, manymsbB Salmonellacells lyse during exponential growth and a fraction of the cells form filaments.msbB Salmonellagrow with a near-wild-type growth rate in MSB (LB-0 containing Mg2+and Ca2+) broth (23 to 42°C). Extragenic compensatory mutations, which partially suppress the growth defects, spontaneously occur at high frequency, and mutants can be isolated on media selective for faster growing derivatives. One of the suppressor mutations maps at 19.8 centisomes and is a recessive IS10insertional mutation insomA, a gene of unknown function which corresponds toybjXinE. coli. In addition, random Tn10mutagenesis carried out in an unsuppressedmsbBstrain produced a set of Tn10inserts, not inmsbBorsomA, that correlate with different suppressor phenotypes. Thus, insertional mutations, insomAand other genes, can suppress themsbBphenotype.
Chemical Structure of a Novel Aminophospholipid from
Hydrogenobacter thermophilus
Strain TK-6
Authors: Yoshino Jun-ichiro , Sugiyama Yasumasa , Sakuda Shohei , Kodama Tohru , Nagasawa Hiromichi , Ishii Masaharu , Igarashi Yasuo 
Published: July 2002

ABSTRACT

The phospholipid composition of
Hydrogenobacter thermophilus
strain TK-6, an obligately chemolithoautotrophic, extremely thermophilic hydrogen bacterium, was analyzed. Two of four phospholipids detected from the strain were assumed to be phosphatidylinositol and phosphatidylglycerol. An aminophospholipid named PX, whose content among the phospholipids was 65%, was found to have a novel chemical structure by analysis of the dilyso form with nuclear magnetic resonance and fast atom bombardment-mass spectrometry (FAB-MS) and by analysis of the intact PX with FAB-MS as 1,2-diacyl-3-
O
-(phospho-2′-
O
-(1′-amino)-2′,3′,4′,5′-pentanetetrol)-sn-glycerol. Structurally similar phospholipids have been identified in
Methanospirillum hungatei
,
Methanolacinia paynteri
, and
Methanogenium cariaci
, which all belong to the
Archaea
.
Modulation of Gonococcal Piliation by Regulatable Transcription of
pilE
Authors: Long Cynthia D. , Hayes Stanley F. , van Putten Jos P. M. , Harvey Hillery A. , Apicella Michael A. , Seifert H. Steven 
Published: July 2002

ABSTRACT

The gonococcal pilus, a member of the type IV family of pili, is composed of numerous monomers of the pilin protein and plays an important role in the initiation of disease by providing the primary attachment of the bacterial cell to human mucosal tissues. Piliation also correlates with efficient DNA transformation. To investigate the relationships between these pilus-related functions, the piliation state, and the availability of pilin, we constructed a derivative of MS11-C9 (Δ
pilE1
) in which the
lacIOP
regulatory sequences control
pilE
transcription. In this strain, MS11-C9.10, the steady-state levels of pilin mRNA and protein directly correlate with the concentration of IPTG (isopropyl-β-
d
-thiogalactopyranoside) in the growth medium and can reach near-wild-type levels of expression. Transmission electron microscopy (TEM) demonstrated that the number of pili per cell correlated with the steady-state expression levels: at a low level of transcription, single long pili were observed; at a moderate expression level, many singular and bundled pili were expressed; and upon full gene expression, increased lateral association between pili was observed. Analysis of pilus assembly by TEM and epithelial cell adherence over a time course of induction demonstrated that pili were expressed as early as 1 h postinduction. Analysis at different steady-state levels of transcription demonstrated that DNA transformation efficiency and adherence of MS11-C9.10 to transformed and primary epithelial cells also correlated with the level of piliation. These data show that modulation of the level of
pilE
transcription, without a change in
pilE
sequence, can alter the number of pili expressed per cell, pilus bundling, DNA transformation competence, and epithelial cell adherence of the gonococcus.
New Host-Vector System for
Thermus
spp. Based on the Malate Dehydrogenase Gene
Authors: Kayser Kevin J. , Kilbane John J. 
Published: July 2002

ABSTRACT

A
Thermus thermophilus
HB27 strain was constructed in which the malate dehydrogenase
(mdh)
gene was deleted. The
Δmdh
colonies are recognized by a small-colony phenotype. Wild-type phenotype is restored by transformation with
Thermus
plasmids or integration vector containing an intact
mdh
gene. The wild-type phenotype provides a positive selection tool for the introduction of plasmid DNA into
Thermus
spp., and because
mdh
levels can be readily quantified, this host-vector system is a convenient tool for monitoring gene expression.
Involvement of the PrrB/PrrA Two-Component System in Nitrite Respiration in
Rhodobacter sphaeroides
2.4.3: Evidence for Transcriptional Regulation
Authors: Laratta William P. , Choi Peter S. , Tosques Ivan E. , Shapleigh James P. 
Published: July 2002

ABSTRACT

Rhodobacter sphaeroides
strain 2.4.3 is capable of diverse metabolic lifestyles, including denitrification. The regulation of many
Rhodobacter
genes involved in redox processes is controlled, in part, by the PrrBA two-component sensor-regulator system, where PrrB serves as the sensor kinase and PrrA is the response regulator. Four strains of 2.4.3 carrying mutations within the
prrB
gene were isolated in a screen for mutants unable to grow anaerobically on medium containing nitrite. Studies revealed that the expression of
nirK
, the structural gene encoding nitrite reductase, in these strains was significantly decreased compared to its expression in 2.4.3. Disruption of
prrA
also eliminated the ability to grow both photosynthetically and anaerobically in the dark on nitrite-amended medium. Complementation with
prrA
restored the wild-type phenotype. The PrrA strain exhibited a severe decrease in both nitrite reductase activity and expression of a
nirK
-
lacZ
fusion. Nitrite reductase activity in the PrrA strain could be restored to wild-type levels by using
nirK
expressed from a heterologous promoter, suggesting that the loss of nitrite reductase activity in the PrrA and PrrB mutants was not due to problems with enzyme assembly or the supply of reductant. Inactivation of
prrA
had no effect on the expression of the gene encoding NnrR, a transcriptional activator required for the expression of
nirK
. Inactivation of
ccoN
, part of the
cbb
3
-type cytochrome oxidase shown to regulate the kinase activity of PrrB, also caused a significant decrease in both
nirK
expression and Nir activity. This was unexpected, since PrrA-P accumulates in the
ccoN
strain. Together, these results demonstrate that PrrBA plays an essential role in the regulation of
nirK
.
Evidence for Lateral Transfer of the Suilysin Gene Region of
Streptococcus suis
Authors: Takamatsu Daisuke , Osaki Makoto , Sekizaki Tsutomu 
Published: July 2002

ABSTRACT

Suilysin is a cholesterol-binding cytolysin encoded by
sly
in
Streptococcus suis
. DNA sequence determination of the
sly
locus in a strain lacking
sly
revealed the presence of another gene, designated
orf102
, in the place of
sly
. No transposable element or long-repeat sequence was found in the close vicinity. Except for six strains whose corresponding loci have been rearranged, all of the remaining 62 strains examined had either
sly
or
orf102
at the same locus and their flanking regions were conserved. The genetic organizations having either
sly
or
orf102
were found in the strains whose 16S rRNA sequences were identical. These results suggest that
S. suis
acquired
sly
or
orf102
from a foreign source and that these genes subsequently spread among
S. suis
strains by homologous recombination.
Evaluation of the Vitek Card GPS105 and VTK-RO7.01 Software for Detection of Oxacillin Resistance in Clinically Relevant Coagulase-Negative Staphylococci
Authors: Martinez Fernando , Chandler Laura J. , Reisner Barbara S. , Woods Gail L. 
Published: July 2002

ABSTRACT

The performance of Vitek cards GPS105 with software version VTK-R07.01 for detection of oxacillin resistance in coagulase-negative staphylococci (CoNS) was compared to disk diffusion and PCR detection for
mecA
. The sensitivity and specificity of the Vitek GPS105 method were 97.6 and 85.5%, respectively.
Clonal Relationship between U.S. and French Serotype V Group B Streptococcus Isolates
Authors: Le Thomas-Bories Isabelle , Fitoussi Frederic , Mariani-Kurkdjian Patricia , Raymond Josette , Brahimi Naima , Bidet Philippe , Lefranc Valerie , Bingen Edouard 
Published: July 2002

ABSTRACT
We examined the genetic diversity of serotype V group B streptococcus (GBS) isolates in the Paris area and compared them with the predominant American serotype V clone. Pulsed-field gel electrophoresis yielded 11 patterns for 64 French GBS. One pattern was obtained with 60% of the isolates tested and was indistinguishable from that of the predominant American clone.
Dissemination of Clonally Unrelated Erythromycin- and Glycopeptide-Resistant
Enterococcus faecium
Isolates in a Tertiary Greek Hospital
Authors: Maniatis Antonios N. , Pournaras Spyros , Kanellopoulou Maria , Kontos Fanourios , Dimitroulia Evangelia , Papafrangas Evangelos , Tsakris Athanassios 
Published: July 2002

ABSTRACT

Between September 1999 to February 2001, 25 glycopeptide-resistant
Enterococcus faecium
(GRE) isolates were recovered from a Greek hospital. The isolates exhibited 13 distinct chromosomal macrorestriction types by pulsed-field gel electrophoresis, and all were erythromycin and vancomycin resistant, carrying the genes
vanA
and
ermB
. Vancomycin resistance, always linked with erythromycin resistance, was transferable from 17 isolates. The dissemination of erythromycin-resistant GRE strains may, at least in part, reflect the extensive use of macrolides in husbandry in Greece.
Comparative Evaluation of Semiautomated COBAS AMPLICOR Hepatitis B Virus (HBV) MONITOR Test and Manual Microwell Plate-Based AMPLICOR HBV MONITOR Test
Authors: Marin Irena J. , Poljak Mario , Seme Katja , Meglic̆-Volkar Jelka , Matic̆ic̆ Mojca , Les̆nic̆ar Gorazd , Brinovec Vladimir 
Published: July 2002

ABSTRACT

Comparative evaluation of the semiautomated COBAS AMPLICOR hepatitis B virus (HBV) MONITOR Test (COBAS-HBV) and manual AMPLICOR HBV MONITOR Test (AMPLICOR-HBV) on 208 serum samples revealed no significant difference in the sensitivities of the two assays. Twenty samples tested HBV DNA negative and 183 samples tested HBV DNA positive by both assays. Three samples tested positive by COBAS-HBV only and two samples tested positive by AMPLICOR-HBV only. HBV DNA concentrations determined by the two assays were significantly related (
n
= 183,
r
= 0.97,
P
< 0.0001), which indicates that COBAS-HBV could replace AMPLICOR-HBV. The major inconvenience of COBAS-HBV is the required performance of appropriate predilutions of high-titer samples in order to extend the narrow dynamic range of the assay.
Identification of a Cluster of Strains Bearing a New Adhesin among Genetically Diverse Enterotoxigenic
Escherichia coli
Isolates of Serogroup O20
Authors: Pichel Mariana , Binsztein Norma , Gutkind Gabriel , Viboud Gloria 
Published: July 2002

ABSTRACT

About one-third of the enterotoxigenic
Escherichia coli
isolates lack any of the known colonization factors. Among this group, those of serogroup O20 are the most frequently isolated in Argentina. By combining analysis of adhesion to Caco-2 cells, random amplified polymorphic DNA, and pulsed-field gel electrophoresis techniques, we were able to identify three sets of closely related strains with different binding properties. Further analysis of the most prevalent group revealed that all these isolates expressed the recently described adhesin CS22.
A Member of the Delta Subgroup of Proteobacteria from a Pyogenic Liver Abscess Is a Typical Sulfate Reducer of the Genus
Desulfovibrio
Authors: Schoenborn Liesbeth , Abdollahi Hamid , Tee Wee , Dyall-Smith Michael , Janssen Peter H. 
Published: July 2002

ABSTRACT

Strain FH26001/95 (ATCC 700045) was previously isolated from a pyogenic liver abscess from a human. Comparative 16S rRNA gene sequence analysis showed that this strain is related to members of the delta subgroup of the proteobacteria, within a cluster of sulfate-reducing bacteria (
Desulfovibrio
spp.) and non-sulfate-reducing bacteria (
Bilophila wadsworthia
and
Lawsonia
spp.). The phenotype of strain FH26001/95 was found to be typical of members of the genus
Desulfovibrio
. Growth and substrate transformations were possible at oxygen concentrations of 2 to 5% (vol/vol) but not at oxygen concentrations of 21% (vol/vol) in air. Its isolation from an infection in a human suggests that some members of the genus
Desulfovibrio
can be considered opportunistic pathogens.
Molecular Epidemiology of a
Shigella flexneri
Outbreak in a Mountainous Township in Taiwan, Republic of China
Authors: Chiou Chien-Shun , Hsu Wen-Bin , Wei Hsiao-Lun , Chen Jiann-Hwa 
Published: July 2002

ABSTRACT

An outbreak of shigellosis occurred in a township of Nantou Conuty in central Taiwan from August to October in 1996. The infections extended to two neighboring townships and continued to the end of 1996. Forty cases were confirmed during the period, in contrast to only one confirmed case in Nantou County in 1996 before the outbreak. All of these 41 cases in 1996 were identified as infections with
Shigella flexneri
serotype 2a. In order to trace the source of the infections, the 41 isolates recovered were analyzed by plasmid profile and pulsed-field gel electrophoresis (PFGE). There was no correlation between the plasmid profile results and the PFGE results, and the latter were used for subtyping of the 41 isolates. Twenty-two isolates (53%) had the same
Not
I and
Xba
I PFGE patterns, and 4 isolates (10%) had an additional unstable plasmid band in their
Not
I patterns but otherwise had the same
Not
I and
Xba
I patterns as the 22 isolates. These 26 isolates were designated the outbreak strain, and of these, 24 appeared in eight villages in one township and 2 appeared in a neighboring township. Fourteen of the remaining 15 isolates, including the isolate recovered 7 months before the outbreak, had both
Not
I and
Xba
I PFGE patterns closely related to those of the outbreak strain, indicating that
Shigella
infections were endemic in the area. By tracing the first isolation dates of the outbreak strain in individual villages and the neighboring township, it was found that the strain spread along the major arterial road and its branch road as time passed. Our molecular typing results and epidemiological data demonstrated the endemic nature of the outbreak strain as well as a person-to-person mode of transmission for the widespread infections the strain caused.
Effect of Errors in the Sequence of Optical Densities from the Roche AMPLICOR HIV-1 MONITOR Assay on the Validity of Assay Results
Authors: Brambilla Donald J. , Granger Suzanne , Jennings Cheryl , Bremer James W. 
Published: July 2002

ABSTRACT
Specifications for the AMPLICOR HIV-1 MONITOR kit indicate that the results are invalid if the optical densities (ODs) from the PCR-amplified sample that are between 0.1 and 2.3 units are out of sequence. However, among 11,904 assays, results were biased only when ODs of 0.2 to 2.0 units were out of sequence, reducing the rate of invalid results from 3.2 to 0.59%.
Antimicrobial Resistance of
Streptococcus pneumoniae
Recovered from Outpatients with Respiratory Tract Infections in Germany from 1998 to 1999: Results of a National Surveillance Study
Authors: Reinert Ralf René , Simic Smiljana , Al-Lahham Adnan , Reinert Susanne , Lemperle Maria , Lütticken Rudolf 
Published: July 2002

ABSTRACT
Clinically significant pneumococcal isolates were prospectively collected from outpatients with respiratory tract infections by 19 different clinical microbiology laboratories in Germany. Resistance rates in a total of 961 isolates were as follows: penicillin, 6.6%; clarithromycin, 10.6%; tetracycline, 13.9%; and levofloxacin, 0.1%. Among 324 isolates from children, pneumococcal serotypes 19F (17.0%), 23F (13.0%), and 6B (11.7%) were the predominant types.
Comparison of Results Generated by Serotyping, Pulsed-Field Restriction Analysis, Ribotyping, and Repetitive-Sequence PCR Used To Characterize Penicillin-Resistant Pneumococci from the United States
Authors: Dunne W. Michael , Kehl Karen Sue , Holland-Staley Carol A. , Brueggemann Angela B. , Pfaller Michael A. , Doern Gary V. 
Published: July 2002

ABSTRACT

One hundred forty-seven isolates of
Streptococcus pneumoniae
with high-level penicillin resistance collected during a national surveillance program in the United States were characterized by serotyping, pulsed-field restriction analysis, ribotyping, and repetitive-sequence (BOX element) PCR. The results generated by each method were compared by frequency of association to examine whether relationships existed between the various typing methods and statistically to determine association with the geographic source of the isolate or the age of the patient from whom the isolate was obtained. When the data were examined by pairwise analysis of individual strain classifications produced by each typing method, no statistically significant relationships between strain type, geographic location, or patient age were identified, suggesting that distinct clones of penicillin-resistant
S. pneumoniae
have been widely distributed throughout the United States. However, we did observed shared expression of two or three typing markers at a high frequency (>50%) among clusters of strains, indicating a certain level of concordance between the various typing methods used to classify penicillin-resistant
S
.
pneumoniae
.