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B Beall

Publications and source records attributed to B Beall.

At least 37 records · Page 2Linked to original sources
PubMed1998

Streptococcal emm types associated with T-agglutination types and the use of conserved emm gene restriction fragment patterns for subtyping group A streptococci.

The T-agglutination types were determined for a diverse collection of 1531 group A streptococci for which the 5' M protein gene (emm) sequences had been analysed. The majority of the T-agglutination types correlated with previously seen M/emm/T-type associations; however, several new associations were found. Analysis of a subset of this collection -- which included 1157 clinical isolates with multiply encountered emm types -- found that emm amplicon restriction profiles of isolates sharing identical T types and opacity factor phenotypes are useful for detecting groups of isolates with identical emm genes. Many emm genes of known 5' sequence display a highly conserved restriction pattern amongst clinical isolates widely separated both geographically and temporally.

Agglutination↗
PubMed1998

Rapid screening for penicillin susceptibility of systemic pneumococcal isolates by restriction enzyme profiling of the pbp2B gene.

Restriction digest profiling of pneumococcal pbp2b-specific amplicons was effective for screening penicillin resistance. The pbp2b amplicon of all pneumococcal isolates for which the MICs of penicillin were < or = 0.03 microgram/ml had one of two different susceptible restriction profiles, and all 33 isolates for which MICs were 0.5 microgram/ml or greater had one of seven distinct resistant profiles. Low-concentration penicillin resistance (MICs = 0.06 microgram/ml to 0.25 microgram/ml) was associated with sensitive HaeIII profiles in some isolates; however, RsaI profiling and pbp2b sequence analysis of such isolates revealed that some isolates contained low-level resistant pbp2b alleles, while others had susceptible pbp2b alleles. This data indicates that low-level penicillin resistance is sometimes conferred by determinants other than pbp2b.

Alleles↗
PubMed1997

A genetic-based evaluation of the principal tissue reservoir for group A streptococci isolated from normally sterile sites.

The primary sites of infection and principal reservoirs for transmission of group A streptococci are the nasopharyngeal mucosa and the impetigo lesion. However, pharyngitis and impetigo are rarely observed prior to invasive disease, and, thus, the origin of invasive strains is largely unknown. As part of an active surveillance program, group A streptococci were obtained from normally sterile tissue sites of Connecticut residents during a 6-month period. Organisms were analyzed for genetic markers that distinguish between strains that use the nasopharynx versus an impetiginous lesion as their primary site for infection. The nasopharyngeal marker was observed for most sterile-site isolates, suggesting that the upper respiratory tract is the principal reservoir from which organisms causing invasive disease are disseminated. Genotypic analyses of sterile-site isolates support the view that additional factors, aside from a recent emergence of a few virulent clones, are important contributors to invasive group A streptococcal disease.

Base Sequence↗
PubMed1997

Survey of emm gene sequences and T-antigen types from systemic Streptococcus pyogenes infection isolates collected in San Francisco, California; Atlanta, Georgia; and Connecticut in 1994 and 1995.

The variable 5' emm (M-protein gene) sequences and T-antigen types were determined from 340 systemic group A streptococcal (GAS) isolates taken from hospitalized patients in San Francisco, Calif.; Atlanta, Ga.; and Connecticut in 1994 and 1995. Eighty percent of these isolates had emm sequences and T-antigen types in agreement with previously recorded M- and T-antigen associations. Most of the remaining strains either were T nontypeable (11%) or contained emm genes encoding M proteins for which T-antigen associations have not been made (6%). One newly encountered emm gene, designated ST2974, from each of 13 isolates had the T type 8/25/Imp19. Another new emm gene, ST2967, from 8 of 11 isolates was T nontypeable. Six other unique emm gene sequences from seven isolates were encountered. Sequencing of the variable region of the emm gene of GAS isolates (emm typing) is effective for surveying the sequence variability of the M virulence protein, and combined with T typing, emm typing is useful for monitoring GAS strain diversity.

Amino Acid Sequence↗
PubMed1996

Sequencing emm-specific PCR products for routine and accurate typing of group A streptococci.

Rapid sequence analysis of specific PCR products was used to accurately deduce emm types corresponding to the majority of the known group A streptococcal (GAS) M serotypes. The study involved 95 M type reference GAS strains and a survey of 74 recent clinical isolates. A high percentage of agreement between M type serology and the previously published 5' sequences of the emm genes of M type reference strains was noted. The 5' sequences for six established M protein genes--the emm-32, emm-34, emm-38, emm-40, emm-42, and emm-71 genes--were determined to supplement the existing emm sequence database. Rapid sequence analysis differentiated serologically M-nontypeable strains and was used to establish the probable.

Amino Acid Sequence↗
PubMed1995

A Bordetella pertussis fepA homologue required for utilization of exogenous ferric enterobactin.

The bfeA (Bordetella ferric enterobactin) receptor gene was cloned from a Bordetella pertussis chromosomal library by using a screen in Escherichia coli to detect iron-repressed genes encoding exported proteins translationally fused to the E. coli phoA gene. The bfeA gene encoded a protein with a molecular mass of approximately 80 kDa and about 50% amino acid sequence identity to both the fepA- and pfeA-encoded enterobactin receptors of E. coli and Pseudomonas aeruginosa, respectively. Enterobactin prepared from iron-starved E. coli cultures supported growth of B. pertussis and Bordetella bronchiseptica in the presence of the iron chelator ethylenediamine-di-(o-hydroxyphenylacetic acid) (EDDA). Expression of the bfeA gene was induced by low iron availability, and iron-regulated expression appeared to be dependent upon the presence of the sequence contained within 370 bp upstream of the bfeA structural gene. An internal fragment of the bfeA structural gene and flanking regions were shown by Southern analysis to be highly conserved among Bordetella species. Insertional inactivation of bfeA in both B. pertussis and B. bronchiseptica greatly impaired their ability to grow in the presence of enterobactin and EDDA. These findings suggest that enterobactin produced by other respiratory flora could aid in the colonization of the respiratory tract by Bordetella species.

Amino Acid Sequence↗
PubMed1995

Analysis of Bordetella pertussis isolates from an epidemic by pulsed-field gel electrophoresis.

We examined genetic variation among 78 clinical isolates of Bordetella pertussis, including 54 strains recovered during a 1986 pertussis epidemic. A total of 16 pulsed-field gel electrophoresis (PFGE) profiles, generated with each of three different enzymes (XbaI, SpeI, and DraI), were obtained from the epidemic and sporadic isolates included in the study. Indistinguishable profiles were seen among strains unrelated temporally or geographically, as well as among strains isolated sporadically from the same geographic areas. All isolates from the epidemic had indistinguishable PFGE profiles. The PFGE pattern of the epidemic strains was shared with only 1 of 25 strains isolated independently of the outbreak. This isolate was cultured from a specimen from a laboratory scientist who had been working with the epidemic strains, further implicating the usefulness of PFGE for the epidemiologic study of clinical strains of B. pertussis. Differences in PFGE profiles for single epidemic strains occurred occasionally upon repeated passage on agar medium, suggesting that subculturing of initial isolates should be minimized before pulsed-field analysis.

Bordetella pertussis↗
PubMed1994

Subcellular localization of proteins involved in the assembly of the spore coat of Bacillus subtilis.

Spores of the bacterium Bacillus subtilis are encased in a two-layered protein shell, which consists of an electron-translucent, lamellar inner coat, and an electron-dense outer coat. The coat protein CotE is both a structural component of the coat and a morphogenetic protein that is required for the assembly of the outer coat. We now show that CotE is located in the outer coat of the mature spore and that at an intermediate stage of sporulation, when the developing spore (the forespore) is present as a free protoplast within the sporangium, CotE is localized in a ring that surrounds the forespore but is separated from it by a small gap. We propose that the ring is the site of assembly of the outer coat and that the gap is the site of formation of the inner coat. Assembly of the ring depends on the sporulation protein SpoIVA, which sits close to or on the surface of the outer membrane that encircles the forespore. We propose that SpoIVA creates a basement layer around the forespore on which coat assembly takes place. The subcellular localization and assembly of CotE and other coat proteins are therefore determined by the capacity of SpoIVA to recognize and adhere to a specific surface within the sporangium, the outer membrane of the forespore.

Bacillus subtilis↗
PubMed1994

Cloning and characterization of spoVR, a gene from Bacillus subtilis involved in spore cortex formation.

Screening for sigma E-dependent promoters led to the isolation of a gene from Bacillus subtilis, designated spoVR, which appears to be involved in spore cortex formation. Cultures of strains carrying mutations in spoVR had an increased proportion of phase-dark spores, which correlated with an increased proportion of cortexless spores seen by electron microscopy. The numbers of heat- and chloroform-resistant phase-bright spores produced by these mutants were decreased by about 3- to 10-fold, and accumulation of dipicolinate was decreased by more than 3-fold. The spoVR gene was located on the B. subtilis chromosome immediately upstream from, and in the opposite orientation of, the phoAIV gene. Expression of spoVR was initiated at the second hour of sporulation from a sigma E-dependent promoter, and this expression did not require any of the other known mother-cell-specific transcriptional regulators. The spoVR gene was predicted to encode a product of 468 residues.

Amino Acid Sequence↗
PubMed1993

Cloning and characterization of a gene required for assembly of the Bacillus subtilis spore coat.

During endospore formation in Bacillus subtilis, approximately a dozen proteins are synthesized and assembled around the prespore to form a protective coat. Little is known about the assembly process, but several of the genes encoding these coat proteins are expressed in the mother cell compartment, where the proteins accumulate on the outer side of the developing endospore. Transcription of these genes is directed by the mother cell-specific sigma factor, sigma K, during the later stages of endospore development. sigma E may direct expression of the genes that encode proteins that function in the earliest stages of coat assembly. By screening for sigma E-dependent promoters, we cloned a gene, designated spoVID, required for assembly of a normal spore coat. Expression of spoVID was initiated at about the second hour of sporulation and continued throughout development from a sigma E-dependent promoter. The spoVID gene was located on the B. subtilis chromosome just downstream of the previously characterized hemAXCDBL operon and is predicted to encode an extremely acidic protein with 575 residues. Insertion mutants of spoVID produced refractile spores that were resistant to heat and to chloroform but were sensitive to lysozyme. Electron microscopic examination of sporulating spoVID mutant cells revealed normal morphological development up to about the third hour of sporulation. However, during the later stages of development the coat proteins assembled into aberrant structures that occurred freely in the mother cell cytoplasm and that consisted of reiterations of the single inner and outer layers that normally make up the spore coat.

Amino Acid Sequence↗
PubMed1992

Genetic suppression analysis of sigma E interaction with three promoters in sporulating Bacillus subtilis.

Genetic evidence suggests that the sigma (sigma) subunit of RNA polymerase determines the specificity of promoter utilization, by making sequence-specific contacts with DNA. We examined the effects of two single amino acid(aa) substitutions in sigma E on the utilization of mutated derivatives of three different promoters in sporulating Bacillus subtilis. We found allele-specific suppression of mutations in all three promoters by each aa substitution in sigma E. These results provide strong evidence that sigma E interacts with each of these promoters in vivo. Moreover, the specificity of suppression of the mutations by the aa substitutions in sigma E lead us to speculate that the Met124 of sigma E closely contacts two adjacent bp in the -10 region of the promoters.

Amino Acids↗
PubMed1992

Impaired cell division and sporulation of a Bacillus subtilis strain with the ftsA gene deleted.

The ftsZ and ftsA genes of Bacillus subtilis are organized in a simple operon expressed from promoter sequences immediately upstream of ftsA. The promoter-distal ftsZ gene is an essential septation gene. In this report, it is shown that the promoter-proximal ftsA gene can be deleted in a previously constructed strain in which the essential gene, ftsZ, is under the control of the inducible spac promoter. Absence of the ftsA gene product resulted in a very filamentous morphology indicating an important role for ftsA in cell division. Also, growth was severely impaired, and viability and sporulation were reduced. The defective sporulation phenotype correlated with a deficiency in the processing of pro-sigma E to its active form.

Bacillus subtilis↗
PubMed1992

Dengue fever: a resurgent risk for the international traveler.

The incidence of dengue fever, an acute febrile illness transmitted by the Aedes aegypti mosquito, is on the rise. High fever, severe headache, skin rash and a variety of constitutional symptoms are hallmarks of classic dengue fever. Dengue hemorrhagic fever, a severe manifestation associated with secondary infection, most often occurs in children. Treatment of classic dengue fever is supportive, whereas urgent rehydration therapy is often required in more severe forms. Community-based and personal strategies for avoiding the mosquito vector represent the best methods of prevention, although vaccine development programs are under way.

Aedes↗
PubMed1991

FtsZ in Bacillus subtilis is required for vegetative septation and for asymmetric septation during sporulation.

A Bacillus subtilis strain was constructed in which the cell division gene, ftsZ, was placed under control of the isopropyl-beta-D-thiogalactoside (IPTG)-inducible spac promoter. This strain was dependent upon the presence of IPTG for cell division and colony formation indicating that ftsZ is an essential cell division gene in this organism. In sporulation medium this strain increased in mass and reached stationary phase in the presence or absence of IPTG, but only sporulated in the presence of IPTG. The expression of the sporulation genes spoIIG, spoIIA, and spoIIE occurred normally in the absence of IPTG as monitored by spo-lacZ fusions. However, expression of lacZ fusions to genes normally induced later in the developmental pathway, and that required processed pro-sigma E for expression, was inhibited. Immunoblot analysis revealed that pro-sigma E was not processed to its active form (sigma E) under these experimental conditions. Electron microscopy revealed that these FtsZ-depleted cells did not initiate asymmetric septation, suggesting that FtsZ has a common role in the initiation of both the vegetative and sporulation septa.

Bacillus subtilis↗
PubMed1989

Nucleotide sequence and insertional inactivation of a Bacillus subtilis gene that affects cell division, sporulation, and temperature sensitivity.

Located at 135 degrees on the Bacillus subtilis genetic map are several genes suspected to be involved in cell division and sporulation. Previously isolated mutations mapping at 135 degrees include the tms-12 mutation and mutations in the B. subtilis homologs of the Escherichia coli cell division genes ftsA and ftsZ. Previously, we cloned and sequenced the B. subtilis ftsA and ftsZ genes that are present on an 11-kilobase-pair EcoRI fragment and found that the gene products and organization of these two genes are conserved between the two bacterial species. We have since found that the mutation in the temperature-sensitive filamenting tms-12 mutant maps upstream of the ftsA gene on the same 11-kilobase-pair EcoRI fragment in a gene we designated dds. Sequence analysis of the dds gene and four other open reading frames upstream of ftsA revealed no significant homology to other known genes. It was found that the dds gene is not absolutely essential for viability since the dds gene could be insertionally inactivated. The dds null mutants grew slowly, were filamentous, and exhibited a reduced level of sporulation. Additionally, these mutants were extremely temperature sensitive and were unable to form colonies at 37 degrees C. Another insertion, which resulted in the elimination of 103 C-terminal residues, resulted in a temperature-sensitive phenotype less severe than that in the dds null mutant and similar to that in the known tms-12 mutant. The tms-12 mutation was cloned and sequenced, revealing a nonsense codon that was predicted to result in an amber fragment that was about 65% of the wild-type size (elimination of 93 C-terminal residues).

Amino Acid Sequence↗
PubMed1988

Cloning and characterization of Bacillus subtilis homologs of Escherichia coli cell division genes ftsZ and ftsA.

The Bacillus subtilis homolog of the Escherichia coli ftsZ gene was isolated by screening a B. subtilis genomic library with anti-E. coli FtsZ antiserum. DNA sequence analysis of a 4-kilobase region revealed three open reading frames. One of these coded for a protein that was about 50% homologous to the E. coli FtsZ protein. The open reading frame just upstream of ftsZ coded for a protein that was 34% homologous to the E. coli FtsA protein. The open reading frames flanking these two B. subtilis genes showed no relationship to those found in E. coli. Expression of the B. subtilis ftsZ and ftsA genes in E. coli was lethal, since neither of these genes could be cloned on plasmid vectors unless promoter sequences were first removed. Cloning the B. subtilis ftsZ gene under the control of the lac promoter resulted in an IPTGs phenotype that could be suppressed by overproduction of E. coli FtsZ. These genes mapped at 135 degrees on the B. subtilis genetic map near previously identified cell division mutations.

Amino Acid Sequence↗