We have previously found that the 𝘨𝘢𝘣 operon of 𝘌𝘴𝘤𝘩𝘦𝘳𝘪𝘤𝘩𝘪𝘢 𝘤𝘰𝘭𝘪 is RpoS regulated suggesting that it plays an important role during stationary phase growth. The specific role of the 𝘨𝘢𝘣 operon is metabolism of γ-aminobutyrate (GABA). GABA, a four carbon amino acid, is the product of the glutamate decarboxylase reaction in 𝘌. 𝘤𝘰𝘭𝘪 and can serve as a source of carbon and nitrogen for members of the 𝘌𝘯𝘵𝘦𝘳𝘰𝘣𝘢𝘤𝘵𝘦𝘳𝘪𝘢𝘤𝘦𝘢𝘦. Interestingly, we found that we could isolate GABA utilizing mutants even when they carried mutations that were predicted to abolish gab function. However, we were only able to isolate GABA utilizing mutants in the 𝘳𝘱𝘰𝘚⁺ background. This suggests two additional features of GABA metabolism in 𝘌. 𝘤𝘰𝘭𝘪. One, that the 𝘨𝘢𝘣 operon in 𝘌𝘴𝘤𝘩𝘦𝘳𝘪𝘤𝘩𝘪𝘢 𝘤𝘰𝘭𝘪 is indeed dispensable for GABA utilization. Secondly, other RpoS regulated functions, independent of 𝘨𝘢𝘣-encoded functions, may allow the cell to metabolize GABA Finally, we have also investigated the inducing effects of GABA on 𝘨𝘢𝘣 expression in minimal and rich media and the role of glutamate in osmo-tolerance and acid adaptation. / Thesis / Master of Science (MSc)

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2010.

Enterococci were once thought to be harmless, commensal organisms that colonize the gastrointestinal tract of humans and other mammals. In the last 30 years, however, concern has grown in the clinical setting over two particular species, Enterococcus faecalis and Enterococcus faecium, which are frequently found to be the etiologic agents of nosocomial infections. Aminoacyl-phosphatidylglycerol synthases (aaPGSs) are integral membrane proteins that add amino acids to phosphatidylglycerol (PG) in the cellular envelope of bacteria. Addition of amino acids to PG confers resistance to various therapeutic antimicrobial agents, and contributes to evasion of the host immune response in a number of clinically relevant microorganisms. E. faecium possesses two distinct aaPGSs: aaPGS1 and aaPGS2. In addition, another gene coding for a putative hydrolase (pHyd) is located in the same operon as aaPGS2, and has no known function. To investigate the physiological relevance of aa-PG formation, and the function of aaPGS1, aaPGS2, and pHyd in E. faecium, we generated individual knockouts of these genes using a markerless deletion strategy. Deletion of aaPGS1 did not noticeably alter lipid aminoacylation, whereas deletion of aaPGS2 led to a loss of aa-PG synthesis. Deletion of pHyd also led to a loss of lipid aminoacylation; however, additional experiments are needed to verify that expression of aaPGS2 (which resides just downstream in the same operon) is unaffected in the pHyd-deletion strain. Development of the mutant strains described here will enable us to investigate additional phenotypes associated with these genes, and to determine whether aa-PG formation contributes to antibiotic resistance in E. faecium as in several other pathogenic microorganisms.

Thesis (M.S.)--University of Alabama at Birmingham, 2008. / Title from first page of PDF file (viewed Sept 22, 2008). Includes bibliographical references (p. 42-45).

Thesis (M.Sc.). / Written for the Dept. of Human Genetics. Title from title page of PDF (viewed 2009/06/18). Includes bibliographical references.

Thesis (Ph.D. in Molecular Biology) -- University of Colorado Denver, 2008. / Typescript. Includes bibliographical references (leaves 134-149). Free to UCD affiliates. Online version available via ProQuest Digital Dissertations;

Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 68-82).

Thesis (Ph. D.)--University of Missouri-Columbia, 2006. / Title from title screen of research.pdf file (viewed on December 22, 2006). The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. "May 2006" Vita. Includes bibliographical references.

The role of Indian hedgehog (Ihh) signalling in the regulation of endochondral bone formation is well established. Ihh controls the rate of bone growth by negatively regulating differentiation and positively regulating growth plate chondrocyte proliferation. It has been well documented also that mutations resulting in constitutive activation of signalling through FGFR3 in chondrodysplasia, lead to a significant decrease in this important signalling factor accompanied by reduced proliferation of the chondrocytes and a dwarf phenotype. / In an attempt to rescue the chondrodysplasia phenotype hedgehog agonist Hh-Ag 1.4 was injected subcutaneously into mice with achondroplasia (ACH) or with severe achondroplasia with developmental delay and acanthosis negricans (SADDAN) with mixed results. / Administration of a hedgehog agonist in SADDAN mice led to a significant up-regulation of both Ptch and Gli1, as measured by quantitative PCR, indicating that Hh-Ag 1.4 does indeed stimulate hedgehog signalling in vivo. Also, in situ hybridization for Ihh seems to show a down regulation of native Ihh expression in pre-hypertrophic chondrocytes, possibly due to the activation of the negative PTHrP feedback loop. In our study, Hh-Ag 1.4 treatment resulted in an increased growth plate length and reduced size of the hypertrophic zone. The cortical bone flanking the growth plate in mice injected with Hh-Ag 1.4 was 2-3 times thicker than in control mice, which may be attributed to the positive effect of increased Ihh signalling in osteoblastogenesis. Contrary to our expectations, there was also a noticeable reduction in chondrocyte proliferation in mice treated with the agonist. / Overall, the effect on the growth of long bones was not beneficial and the treatment with high doses of Hh-Ag 1.4 did not result in an amelioration of the chondrodysplastic phenotype.

Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 6 uppsatser.