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Microalgae and Cyanobacteria as a Potential Source of Anticancer Compounds
Published in Gokare A. Ravishankar, Ranga Rao Ambati, Handbook of Algal Technologies and Phytochemicals, 2019
A wide range of biologically active peptides isolated from microalgae and cyanobacteria are known to possess great therapeutic potential, and these have attracted much interest from the pharmaceutical industries (Gerwick and Moore 2012). These peptides from microalgae usually consist of 10–20 amino-acid residues and can be released by solvent extraction, enzymatic hydrolysis or microbial fermentation (Giordano et al. 2018). There are distinct structural classes of peptides, which include linear peptides, linear depsipeptides, linear lipopeptides, cyclic peptides, cyclic depsipeptides and cyclic lipopeptides (Mi et al. 2017). In terms of biosynthesis, some peptides are synthesized by a multiple enzyme system, such as nonribosomal peptide synthetase (NRPS) or polyketide synthase hybrid (NRPS/PKS) pathways, while other peptides are gene-coded, ribosomally synthesized and posttranslationally modified. Marine cyanobacteria represent a rich source of peptide metabolites in terms of structure and bioactivity. For instance, programs for drug discovery from marine cyanobacteria, such as the Panama International Cooperative Biodiversity Group (ICGB) program, have discovered more than 400 new peptide compounds between 2007 and 2016 (Mi et al. 2017). Many of the bioactive peptides derived from cyanobacteria were found to display anticancer activity.
Proteus
Published in Dongyou Liu, Laboratory Models for Foodborne Infections, 2017
Paola Scavone, Victoria Iribarnegaray, Pablo Zunino
Iron acquisition systems are an important virulence determinant that enhances bacterial colonization of the host cells and survival in the environment [25]. Iron is an essential micronutrient for all living organisms, and its acquisition is vital for bacteria considering that only a minor fraction is available (10−18 M). In order to capture iron, bacteria have evolved high-affinity iron-scavenging and uptake systems [25]. The main strategies used by bacteria are the production and uptake of siderophores and the direct utilization of host iron compounds such as transferrin, lactoferrin, or heme-containing molecules [25]. Gram-negative Fe(III) acquisition systems usually consist of an outer membrane receptor, with transport across the outer membrane by TonB/ExbB/ExbD complex, a periplasmic binding protein, and an inner membrane ABC transporter. In P. mirabilis, there are at least two gene clusters related to siderophore biosynthesis and ABC transport, three outer membrane proteins induced by iron starvation involved in heme uptake, and a heme receptor [26,27]. One of the clusters related to siderophore biosynthesis is a novel nonribosomal peptide syntheses (NRPS)-independent siderophore (NIS) named proteobactin, as this was first described in a bacterium [28]. The other one contains the nrp operon, which has been previously described to be upregulated during iron limitation [29]. This operon is encoded within the high pathogenicity island (HPI) in P. mirabilis HI4320 that shows homology compared to the HPI of Yersinia spp. [30]. Infection challenges with mutant strains in different genes involved in yersiniabactin-related siderophore showed that it contributes to P. mirabilis fitness in vivo [31].
Shortcomings and Alternatives
Published in Willi Kullmann, Enzymatic Peptide Synthesis, 1987
If nature cannot supply the peptide synthetic chemist with an adequate set of proteases one might proceed according to the motto: “Need a catalyst? Design an enzyme”.17 A variety of proteinaceous and nonproteinaceous compounds have been prepared in an effort to mimic the catalytic action of proteases. (The following references only give a limited survey of this challenging field of enzyme chemistry, 18 to 27.) However, the studies to date on protease mimetics have focused predominantly on their hydrolytic activities, while few reports on enzyme models displaying proteosynthetic capacities have been published. In this respect, the work of Sasaki et al.28 on the preparation of an artificial catalyst for the synthesis of peptide bonds represents a rare exception. These authors used a crown ether as scaffold to which two thiol-groups were fixed as catalytic functions. The artificial enzyme thus resembled a miniature organic model of the antibiotic synthetases which function as catalysts in nonribosomal peptide biosynthesis.29 The educts, i.e., the carboxyl- and the amine component, were covalently linked by chemical means to the enzyme mimic via thioester bonds (Figure 2). Intramolecular aminolysis resulted in the formation of a peptide bond with the growing peptide chain still bound to the carrier through a thioester linkage. After successive rounds of amino acid addition the completed tetrapeptide was finally cleaved from the crown ether by methanolysis. Although the binding of the substrates to the enzyme mimetic involved purely chemical steps, the respective peptide-bond-forming processes can be regarded as being enzyme-catalyzed. Consequently, the outcome of this study is encouraging and should stimulate further efforts in this field.
Inhibition of heterotrophic bacterial biofilm in the soil ferrosphere by Streptomyces spp. and Bacillus velezensis
Published in Biofouling, 2022
Nataliia Tkachuk, Liubov Zelena
Although antagonistic properties of S. canus strain NUChC F2 have not been observed, various strains of S. canus have been studied in the past and a number of compounds with antifungal and bactericidal activity have been identified (Zhang et al. 2013). In particular S. canus strain C-509 (ATCC 12647) was found to produce telomycin, an antibiotic with marked bactericidal activity (Hooper et al. 1962; Fu et al. 2015). S. canus strain IMCC 34906 was indicated among microorganisms with antimicrobial potential and isolated from Nepalese Soil (Khadayat et al. 2020). Liu et al. (2016) performed whole genome sequence of S. canus strain ATCC 12647. Twelve secondary metabolite biosynthetic gene clusters were identified, of which three were nonribosomal peptides, six were polyketides, one was another hybrid peptide-polyketide, and two were other metabolites. The complete nonribosomal peptide gene cluster responsible for the production of telomycin and its associated analogues was identified. Researchers also observed gene clusters with high homology scores corresponding to those known to produce coelichelin and albaflavenone. Other remaining nonribosomal peptide, polyketide, and hybrid clusters of substantial size are also present with yet-unknown identity (Liu et al. 2016).
Bioactive cyclic molecules and drug design
Published in Expert Opinion on Drug Discovery, 2018
However, in the last few years, a major discovery in peptide-based natural products, both linear and cyclic, was the identification of the biosynthetic process that led to what are known as RiPPs as a major source of bioactive peptides. The compounds that were identified from this ‘new process,’ were peptides that initially were products of ribosomal synthesis from the usual proteinogenic aminoacids, which following subsequent post-translational modification, yielded peptides that have been found in all of the three domains of life—archaea, prokarya, and eukarya. Using analogy with the biosynthetic non-ribosomal peptide synthetase (NRPS) enzymes that catalyzed the known modular assembly line, Arnison et al[17] suggested that the biosynthetic pathway(s) to these compounds be referred to as post-ribosomal peptide synthesis (PRPS).
Strategies for recombinant production of antimicrobial peptides with pharmacological potential
Published in Expert Review of Clinical Pharmacology, 2020
Kamila Botelho Sampaio de Oliveira, Michel Lopes Leite, Gisele Regina Rodrigues, Harry Morales Duque, Rosiane Andrade da Costa, Victor Albuquerque Cunha, Lorena Sousa de Loiola Costa, Nicolau Brito da Cunha, Octavio Luiz Franco, Simoni Campos Dias
Nonribosomal peptides (NRP) are molecules synthesized by huge enzymatic complexes called nonribosomal peptide synthetases (NRPSs). Enzymatic complexes of this ‘mega-enzyme’ type are able to synthesize short cyclic or linear peptides (usually up to 20 amino acid residues) using as building-blocks D and L amino acids, besides exotic amino acids, which can be conjugated to a glycidic, a lipidic or an acyl chain, contributing to a wide diversity of molecules [234]. A mega-enzyme usually synthesizes a family of nonribosomal peptides, that is, more than one peptide isoform which presents a core of amino acid residues, and this allows variations of amino acids at specific points on the chain [235,236].