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Niemann-Pick type C disease/cholesterol-processing abnormality
Published in William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop, Atlas of Inherited Metabolic Diseases, 2020
The NPC1 gene contains 25 exons over 47 kb [65]. It predicts a protein of 1278 amino acids [12]. The protein appears to be a permease which acts as a transmembrane efflux pump [14]. It has extensive homology to other proteins, including the murine ortholog, and to patched, the defect in the basal cell nevus syndrome [66], which is also related to the sonic hedgehog signaling pathway; and to proteins involved in cholesterol homeostasis. Eight mutations were originally found in five patients, two deletions, one insertion, and five missense mutations. In Japan, mutations identified included two splicing abnormalities [67]. In the Nova Scotian French isolate the defect was a missense mutation c.G3097T which led to p.G992W [68]. A considerable number and variety of unique mutations have now been found [69]. The only common Caucasian mutation is p.I1061T, when homozygous leads to a juvenile neurologic phenotype [70]. This mutation has been found in the Hispanic-American isolate in Colorado and New Mexico. In most populations, compound heterozygosity is the rule [71].
Transport of Radiolabeled Enzymes
Published in Lelio G. Colombetti, Biological Transport of Radiotracers, 2020
Certain antibiotics (notably sulfanilamide and its derivatives) and alkaloids bind strongly to some enzymes. The resulting complexes can be made radioactive by labeling the binding agent and then used to study the biological transport of the enzymes in vivo. The value of this technique may be illustrated by the following examples. Bleomycin has been labeled with 57Co by Cohen et al.42 and with 99wTc by Plagne et al.43 Müller and Zahn44 have shown that the enzymatic incorporation of thymine in nucleic acids is inhibited if the enzyme is complexed with a labeled antibiotic. Cohen’s results45 indicate that chloramphenicol inhibits the fixation of mRNA on bacterial ribosomes and blocks the inducing μ-galactoside permease. The biological transport of this permease may be studied in vitro by using chloramphenicol labeled with l5N. Benzyl penicillin labeled with 14C can be used to label mucopeptidases involved in the synthesis of bacterial cell walls.
The Mannitol Enzyme II of the Bacterial Phosphotransferase System: A Functionally Chimaeric Protein with Receptor, Transport, Kinase, and Regulatory Activities
Published in James F. Kane, Multifunctional Proteins: Catalytic/Structural and Regulatory, 2019
Milton H. Saier, John E. Leonard
Our recent efforts to elucidate the mechanisms of Enzyme II mediated functions have resulted in the isolation of homogeneous Enzyme IIMtl and in the cloning of mannitol operon DNA. A restriction map of the plasmid pLC 15-48 is now available,54 and the complete DNA sequence of the operon should be available in the foreseeable future. These advances render the mannitol Enzyme II the most amenable for study among the Enzymes II. Moreover, it is among the best characterized of permease proteins. The results reported here emphasize the multifunctional nature of the protein both in catalysis and regulation (Table 1). Further studies employing a combined genetic, biochemical, biophysical, and physiological approach should yield startling new insights into such related fields as membrane protein structure, permease function, chemoreception, transcriptional regulation, and the evolution of protein multifunctionality. The mannitol operon is likely to be at the forefront of membrane molecular biological research for many years to come.
Targeting the gut microbial metabolic pathway with small molecules decreases uremic toxin production
Published in Gut Microbes, 2020
Yingyi Wang, Jianping Li, Chenkai Chen, Jingbo Lu, Jingao Yu, Xuejun Xu, Yin Peng, Sen Zhang, Shu Jiang, Jianming Guo, Jinao Duan
Tryptophan is transported by TnaB permease, which is found in the bacterial plasma membrane and plays an important role in the transport of tryptophan. Polysorbate-80 (PS80), a nonionic surfactant, increases the permeability of the bacterial membrane.36,37 Therefore, in the presence of PS80, tryptophan directly passes through the bacterial membrane without the aid of TnaB permease. Accordingly, we hypothesized that in the presence of PS80 more tryptophan molecules would enter the bacteria, leading to attenuation of the inhibitory effect of ISO on tryptophan transport. As we postulated, tryptophan intake increased when 0.5% (v/v) PS80 was added to the LB medium (Figure 2e). As a consequence, the inhibitory effect of ISO on indole production and tryptophan consumption decreased after treatment with 0.5% (v/v) PS80 for 8 h.
Synergistic antibacterial and anti-biofilm activity of nisin like bacteriocin with curcumin and cinnamaldehyde against ESBL and MBL producing clinical strains
Published in Biofouling, 2020
Garima Sharma, Shweta Dang, Aruna K, Manjula Kalia, Reema Gabrani
E. coli ML-35p has been genetically modified to express cytoplasmic β-galactosidase but cannot produce lactose permease (Epand et al. 2010). Nisin like bacteriocin-GAM217 appeared to alter membrane permeability, resulting in leakage of the intracellular enzyme in a time-dependent manner as evident by the increase in absorbance (Figure 3). SDS (0.1%) treated cells were used as positive control. The statistical significance analysed by Tukey’s HST test showed that the treatment group was significantly different from untreated cells. These results were in agreement with previous reports where two bacteriocins (nisin and lactacin F) from L. lactis have been reported for channel formation as their mode of action to target bacterial cells, as studied by the planar lipid bilayer method (Héchard and Sahl 2002). Lactoccocin A, another bacteriocin from L. lactis, has been reported to kill bacterial cells by causing pore formation (Yildirim et al. 2007).
The ‘in vivo lifestyle’ of bile acid 7α-dehydroxylating bacteria: comparative genomics, metatranscriptomic, and bile acid metabolomics analysis of a defined microbial community in gnotobiotic mice
Published in Gut Microbes, 2020
Jason M. Ridlon, Saravanan Devendran, João Mp Alves, Heidi Doden, Patricia G. Wolf, Gabriel V. Pereira, Lindsey Ly, Alyssa Volland, Hajime Takei, Hiroshi Nittono, Tsuyoshi Murai, Takao Kurosawa, George E. Chlipala, Stefan J. Green, Alvaro G. Hernandez, Christopher J. Fields, Christy L. Wright, Genta Kakiyama, Isaac Cann, Purna Kashyap, Vance McCracken, H. Rex Gaskins
Carbohydrate metabolism by bile acid 7α-dehydroxylating Firmicutes appears to be largely restricted to simple monosaccharides and disaccharides.27,39 A gene cluster (LAJLEIBI_01095-LAJLEIBI_01102) predicted to be involved in D-galactose import and metabolism was highly expressed. A gene predicted to encode D-galactose-binding periplasmic protein (LAJLEIBI_01095; 62,483.9 ± 9,167.6 TPM) and with galactose import ATP-binding protein mglA (LAJLEIBI_01096; 4,776.5 ± 675.5 TPM), and galactose transport system permease mglC (LAJLEIBI_01097; 1,559.0 ± 240.96 TPM) were highly upregulated. Interestingly, a gene encoding a putative neopullalanase (tvaI) (LAJLEIBI_00506; 243 ± 76.6 TPM), a 1,4-α-glucan branching enzyme (glgB) (LAJLEIBI_00659; 129 ± 51.8 TPM), and an acetylxylan esterase (LAJLEIBI_00751; 392.1 ± 143.8 TPM) were also expressed in the cecum, suggesting the potential for some limited metabolism of complex carbohydrates.