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Escherichia coli: Structure, Function, and Toxoid Vaccine Development
Published in Yoshikatsu Murooka, Tadayuki Imanaka, Recombinant Microbes for Industrial and Agricultural Applications, 2020
W. Neal Burnette, Witold Cieplak, Harvey R. Kaslow, Rino Rappuoli, Elaine I. Tuomanen
The principal pathological effects produced by several bacterial species are mediated by a class of secreted enzyme toxins, termed ADP-ribosyltransferases [1,2]. Of these, five such organisms employ so-called mono(ADP-ribosyl)transferases that catalyze the hydrolysis of NAD and covalently transfer the ADP-ribose cleavage product to sensitive intracellular substrate targets, resulting in cytopathic effects that correlate with toxic consequences in the infected host. The enzymatic toxins of Bordetella pertussis, Vibrio choierae, and enterotoxigenic Escherichia coli exert their action by covalent modification of the α-subunit of heterotrimeric guanyl nucleotide-binding proteins (G proteins) involved in the transduction of certain receptor-coupled agonist regulatory signals that modulate control of intracellular adenylate cyclase [1,3-5]. Two other important bacterial toxins also possess ADP-ribosyltransferase activity: diphtheria toxin (DT) of Corynebacterium diphtheriae and exotoxin A (ETA) of Pseudomonas; each inhibit cellular protein synthesis by ADP-ribosylation of elongation factor 2 [6-10]. Because of their similar substrate specificities and their immediate potential for recombinant vaccine development, we shall limit the discussion herein to the toxins of B. pertussis, V. choierae, and enterotoxigenic E. coli.
Photodynamic Therapy: Membrane and Enzyme Photobiology
Published in Barbara W. Henderson, Thomas J. Dougherty, Photodynamic Therapy, 2020
Tom M. A. R. Dubbelman, Carla Prinsze, Louis C. Penning, John van Steveninck
β-Polymerase activity is decreased to about 50% of the initial values after 30 min of illumination, but recovers during postincubation within 16 hr. Ligase activity is modulated by adenosine diphosphate (ADP) ribosylation; the enzyme, oxidized nicotonamide-adenine dinucleotide (NAD+):protein ADP-ribosyl-transferase (ADPRT; EC 2.4.2.30), is activated by the formation of DNA strand breaks. Thus if ADPRT is inactivated, ligase activity remains low, and strand breaks persist. Indeed, in L929 cells, the increase of ADPRT activity induced by ionizing radiation or methylation (in both cases by a factor of about 2) is inhibited by a photodynamic treatment of 15 min or longer (Fig. 2).
Proliferation of mouse embryonic stem cells on substrate coated with intact silkworm sericin
Published in The Journal of The Textile Institute, 2022
Chihiro Umehara, Ai Ai Lian, Yuichiro Funahashi, Keiko Takaki, Rina Maruta, Yuto Ohmaru, Yoko Okahisa, Takashi Aoki, Hajime Mori, Eiji Kotani
To obtain specific cocoons for the effective preparation of intact sericin, we generated transgenic silkworms with modified PSGs expressing the N-terminal enzymatic region of the cabbage butterfly cytotoxin pierisin-1A (P1A) (P1A; Otsuki et al., 2017). Expressed P1A protein suppressed fibroin gene expression in the PSG by DNA ADP-ribosylation. The transgenic silkworm spin cocoons were nearly fibroin-free and composed almost entirely of sericin, as confirmed by the results of highly sensitive immunoblotting with specific antibodies (Otsuki et al., 2017). We were able to extract the intact sericin using a chemical treatment described by Teramoto et al. (2005). Intact sericin solutions prepared from fibroin free-cocoons were found to be involved in the inhibition of bacterial growth (Matsumoto et al., 2021), which is advantageous for cell culture systems.