hisB

About: hisB is a research topic. Over the lifetime, 57 publications have been published within this topic receiving 1954 citations.

Health Information—Seeking Behavior

Abstract: Seeking information about one's health is increasingly documented as a key coping strategy in health-promotive activities and psychosocial adjustment to illness. In this article, the authors critically examine the scientific literature from 1982 to 2006 on the concept of health information-seeking behavior (HISB) to determine its level of maturity and clarify the concept's essential characteristics. A principle-based method of concept analysis provides the framework for exploring the nature of HISB. The authors reviewed approximately 100 published articles and five books reporting on HISB. Although HISB is a popular concept used in various contexts, most HISB definitions provide little insight into the concept's specific meanings. The authors describe the concept's characteristics, contributing to a clearer understanding of HISB, and discuss operationalizations, antecedents, and outcomes of HISB. Such an analysis of HISB might guide further theorizing on this highly relevant concept and assist health care providers in designing optimal informational interventions.

Production of a functional eukaryotic enzyme in Escherichia coli: cloning and expression of the yeast structural gene for imidazole-glycerolphosphate dehydratase (his3).

Abstract: A cloned segment of yeast DNA containing the structural gene for imidazoleglycerolphosphate dehydratase (D-erythro-imidazoleglycerolphosphate hydro-lase, EC 4.2.1.19) is transcribed and translated in Escherichia coli with sufficient fidelity to produce functional enzyme. This segment of yeast DNA was isolated as a viable molecular hybrid of bacteriophage lambda (lambdagt-Sc2601) which complements a nonrevertible hisB auxotroph of E. coli lacking dehydratase activity. The equivalent segments of DNA cloned from two independent his3 mutants of yeast lacking IGP dehydratase activity do not complement the hisB auxotroph. The two nonfunctional his3 alleles cloned in bacteriophage lambda can be recombined in E. coli to generate a hybrid phage which complements the hisB auxotroph. The dehydratase activity produced in E. coli by the cloned segment of yeast DNA strongly resembles the activity found in yeast.

Histidine biosynthesis genes in Lactococcus lactis subsp. lactis

Abstract: The genes of Lactococcus lactis subsp. lactis involved in histidine biosynthesis were cloned and characterized by complementation of Escherichia coli and Bacillus subtilis mutants and DNA sequencing. Complementation of E. coli hisA, hisB, hisC, hisD, hisF, hisG, and hisIE genes and the B. subtilis hisH gene (the E. coli hisC equivalent) allowed localization of the corresponding lactococcal genes. Nucleotide sequence analysis of the 11.5-kb lactococcal region revealed 14 open reading frames (ORFs), 12 of which might form an operon. The putative operon includes eight ORFs which encode proteins homologous to enzymes involved in histidine biosynthesis. The operon also contains (i) an ORF encoding a protein homologous to the histidyl-tRNA synthetases but lacking a motif implicated in synthetase activity, which suggests that it has a role different from tRNA aminoacylation, and (ii) an ORF encoding a protein that is homologous to the 3'-aminoglycoside phosphotransferases but does not confer antibiotic resistance. The remaining ORFs specify products which have no homology with proteins in the EMBL and GenBank data bases.

Gene inactivation in Lactococcus lactis : histidine biosynthesis

Abstract: Lactococcus lactis strains from dairy and nondairy sources were tested for the ability to grow in the absence of histidine. Among 60 dairy strains tested, 56 required histidine, whereas only 1 of 11 nondairy strains had this requirement. Moreover, 10 of the 56 auxotrophic strains were able to grow in the presence of histidinol (Hol+), the immediate histidine precursor. This indicates that adaptation to milk often results in histidine auxotrophy. The histidine operon was detected by Southern hybridization in eight dairy auxotrophic strains tested. A large part of the histidine operon (8 kb, containing seven histidine biosynthetic genes and three unrelated open reading frames [ORFs]) was cloned from an auxotroph, which had an inactive hisD gene, as judged by its inability to grow on histidinol. Complementation analysis of three genes, hisA, hisB, and hisG, in Escherichia coli showed that they also were inactive. Sequence analysis of the cloned histidine region, which revealed 98.6% overall homology with that of the previously analyzed prototrophic strain, showed the presence of frameshift mutations in three his genes, hisC, hisG, and hisH, and two genes unrelated to histidine biosynthesis, ORF3 and ORF6. In addition, several mutations were detected in the promoter region of the operon. Northern (RNA) hybridization analysis showed a much lower amount of the his transcript in the auxotrophic strain than in the prototrophic strain. The mutations detected account for the histidine auxotrophy of the analyzed strain. Certain other dairy auxotrophic strains carry a lower number of mutations, since they were able to revert either to a Hol+ phenotype or to histidine prototrophy.